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1

Dinosaurs and other fossil vertebrates from the Late Jurassic and Early Cretaceous of the Galve area, NE Spain  

E-print Network

Dinosaurs and other fossil vertebrates from the Late Jurassic and Early Cretaceous of the Galve in an Upper Jurassic to Lower Cretaceous succession spanning some 30 myr, divided into five formations rights reserved. Keywords: Upper Jurassic­Lower Cretaceous; Galve; Spain; Vertebrate palaeontology

Benton, Michael

2

Exceptionally preserved insect fossils in the Late Jurassic lagoon of Orbagnoux (Rh?ne Valley, France)  

PubMed Central

The Late Kimmeridgian marine limestones of the area around Orbagnoux (Rhône, France) are well known for their fish fauna and terrestrial flora. Here we record the first insects and their activities (mines on leaves and trails in sediments) from these layers, including the oldest record of the gerromorphan bugs, as a new genus and species Gallomesovelia grioti, attributed to the most basal family Mesoveliidae and subfamily Madeoveliinae. These new fossils suggest the presence of a complex terrestrial palaeoecosystem on emerged lands near the lagoon where the limestones were deposited. The exquisite state of preservation of these fossils also suggests that these outcrops can potentially become an important Konservat-Lagerstätte for the Late Jurassic of Western Europe. PMID:25210652

Nel, Patricia; Krieg-Jacquier, Regis; Pouillon, Jean-Marc

2014-01-01

3

Exceptionally preserved insect fossils in the Late Jurassic lagoon of Orbagnoux (Rhône Valley, France).  

PubMed

The Late Kimmeridgian marine limestones of the area around Orbagnoux (Rhône, France) are well known for their fish fauna and terrestrial flora. Here we record the first insects and their activities (mines on leaves and trails in sediments) from these layers, including the oldest record of the gerromorphan bugs, as a new genus and species Gallomesovelia grioti, attributed to the most basal family Mesoveliidae and subfamily Madeoveliinae. These new fossils suggest the presence of a complex terrestrial palaeoecosystem on emerged lands near the lagoon where the limestones were deposited. The exquisite state of preservation of these fossils also suggests that these outcrops can potentially become an important Konservat-Lagerstätte for the Late Jurassic of Western Europe. PMID:25210652

Nel, André; Nel, Patricia; Krieg-Jacquier, Régis; Pouillon, Jean-Marc; Garrouste, Romain

2014-01-01

4

Notoatherix antiqua gen. et sp. nov., first fossil water snipe fly from the Late Jurassic of Australia (Diptera: Athericidae).  

PubMed

The first water snipe fly (Diptera: Tabanomorpha) fossil discovered in the Late Jurassic Talbragar Fish Bed in Australia is described and illustrated. Notoatherix antiqua gen. et sp. nov., described from a single wing specimen, is assigned to the family Athericidae based on the diagnostic feature of this family: the vein R2+3 ending very near to R1 (marginal cell closed). It is the first record of Athericidae from Australia and the oldest adult record of this family worldwide.  PMID:25283652

Oberprieler, Stefanie K; Yeates, David K

2014-01-01

5

Dinosaurs and other fossil vertebrates from the Late Jurassic and Early Cretaceous of the Galve area, NE Spain  

Microsoft Academic Search

Since 1950, diverse assemblages of Mesozoic vertebrates have been described from the Galve area (Teruel Province, NE Spain). More than fifty taxa have been noted, including fishes, crocodyliforms, pterosaurs, dinosaurs and mammals. The Galve fossil sites occur in an Upper Jurassic to Lower Cretaceous succession spanning some 30 myr, divided into five formations, representing marginal marine and continental settings, with a

Bárbara Sánchez-Hernández; Michael J. Benton; Darren Naish

2007-01-01

6

A new carnivorous dinosaur from the Late Jurassic Solnhofen archipelago.  

PubMed

Small Late Jurassic theropod dinosaurs are rare worldwide. In Europe these carnivorous dinosaurs are represented primarily by only two skeletons of Compsognathus, neither of which is well preserved. Here we describe a small new theropod dinosaur from the Late Jurassic period of Schamhaupten in southern Germany. Being exquisitely preserved and complete from the snout to the distal third of the tail, the new fossil is the best-preserved predatory, non-avian dinosaur in Europe. It possesses a suite of characters that support its identification as a basal coelurosaur. A cladistic analysis indicates that the new taxon is closer to maniraptorans than to tyrannosauroids, grouping it with taxa often considered to be compsognathids. Large portions of integument are preserved along its tail. The absence of feathers or feather-like structures in a fossil phylogenetically nested within feathered theropods indicates that the evolution of these integumentary structures might be more complex than previously thought. PMID:16541071

Göhlich, Ursula B; Chiappe, Luis M

2006-03-16

7

A late Jurassic pterosaur (Reptilia, Pterodactyloidea) from northwestern Patagonia, Argentina  

NASA Astrophysics Data System (ADS)

A small to medium-sized pterodactyloid pterosaur (wingspan approximately 1.10 m) from the Upper Jurassic (middle-late Tithonian) marine deposits of the Vaca Muerta Formation of Patagonia (Los Catutos area, central Neuquén Province, Argentina) is reported. The specimen lacks the skull but constitutes a nearly complete postcranial skeleton, which includes cervical and dorsal vertebrae; a few thoracic ribs; both pectoral girdles; the left pelvic girdle; a proximal right wing (humerus, ulna, and radius) and metacarpal IV; a left wing that lacks only wing phalanx four; and both hindlimbs, the right one without the foot. Ontogenetic features suggest that the new fossil corresponds to a relatively mature individual, probably a subadult. Observed characters support its assignment to the Archaeopteroactyloidea, a basal clade within the Pterodactyloidea. This specimen is the second pterosaur from Los Catutos and the most complete Jurassic pterosaur so far known from South America.

Codorniú, Laura; Gasparini, Zulma; Paulina-Carabajal, Ariana

2006-03-01

8

The Late Jurassic Tithonian, a greenhouse phase in the Middle JurassicEarly Cretaceous `cool' mode: evidence from the cyclic  

E-print Network

The Late Jurassic Tithonian, a greenhouse phase in the Middle Jurassic­Early Cretaceous `cool' mode of cyclic facies within the rapidly subsiding Late Jurassic (Tithonian) shallow platform-interior (over 750), supporting a global, hot greenhouse climate for the Late Jurassic (Tithonian) within the overall `cool' mode

Husinec, Antun

9

Earliest evolution of multituberculate mammals revealed by a new Jurassic fossil.  

PubMed

Multituberculates were successful herbivorous mammals and were more diverse and numerically abundant than any other mammal groups in Mesozoic ecosystems. The clade also developed diverse locomotor adaptations in the Cretaceous and Paleogene. We report a new fossil skeleton from the Late Jurassic of China that belongs to the basalmost multituberculate family. Dental features of this new Jurassic multituberculate show omnivorous adaptation, and its well-preserved skeleton sheds light on ancestral skeletal features of all multituberculates, especially the highly mobile joints of the ankle, crucial for later evolutionary success of multituberculates in the Cretaceous and Paleogene. PMID:23950536

Yuan, Chong-Xi; Ji, Qiang; Meng, Qing-Jin; Tabrum, Alan R; Luo, Zhe-Xi

2013-08-16

10

A new carnivorous dinosaur from the Late Jurassic Solnhofen archipelago  

Microsoft Academic Search

Small Late Jurassic theropod dinosaurs are rare worldwide. In Europe these carnivorous dinosaurs are represented primarily by only two skeletons of Compsognathus, neither of which is well preserved. Here we describe a small new theropod dinosaur from the Late Jurassic period of Schamhaupten in southern Germany. Being exquisitely preserved and complete from the snout to the distal third of the

Ursula B. Göhlich; Luis M. Chiappe

2006-01-01

11

Late Jurassic climate and its impact on carbon cycling  

Microsoft Academic Search

The climate of the Late Jurassic has been characterized by high atmospheric CO2 levels and by a monsoonal rainfall pattern. In this study we traced the evolution of the global carbon cycle through the Late Jurassic with the help of carbonate carbon isotope stratigraphy. The Oxfordian-Tithonian ?13C curve is marked by one major positive carbon isotope excursion with an amplitude

H. Weissert; H. Mohr

1996-01-01

12

A high-resolution three-dimensional reconstruction of a fossil forest (Upper Jurassic Shishugou Formation, Junggar Basin, Northwest China)  

Microsoft Academic Search

This study focuses on the three-dimensional (3D) reconstruction of an Late Jurassic fossil forest based on a fossil assemblage\\u000a located in the Shishugou Formation near Jiangjunmiao, north-eastern Junggar Basin, Xinjiang Uygur Autonomous Region, Northwest\\u000a China. On the basis of tree stumps found in growth position together with published data on megaplant fossils, seeds and spores,\\u000a a high-resolution digital computer model,

Juliane K Hinz; Ian Smith; Hans-Ulrich Pfretzschner; Oliver Wings; Ge Sun

2010-01-01

13

Direct evidence of hybodont shark predation on Late Jurassic ammonites  

NASA Astrophysics Data System (ADS)

Sharks are known to have been ammonoid predators, as indicated by analysis of bite marks or coprolite contents. However, body fossil associations attesting to this predator-prey relationship have never been described so far. Here, I report a unique finding from the Late Jurassic of western France: a complete specimen of the Kimmeridgian ammonite Orthaspidoceras bearing one tooth of the hybodont shark Planohybodus. Some possible tooth puncture marks are also observed. This is the first direct evidence of such a trophic link between these two major Mesozoic groups, allowing an accurate identification of both organisms. Although Planohybodus displays a tearing-type dentition generally assumed to have been especially adapted for large unshelled prey, our discovery clearly shows that this shark was also able to attack robust ammonites such as aspidoceratids. The direct evidence presented here provides new insights into the Mesozoic marine ecosystem food webs.

Vullo, Romain

2011-06-01

14

A new fossil genus of Mesosciophilidae (Diptera, Nematocera) with two new species from the Middle Jurassic of Inner Mongolia, China  

Microsoft Academic Search

A new genus within the family Mesosciophilidae, Jurasciophila gen. nov., with two new species, J. curvula gen. et sp. nov. and J.lepida gen. et sp. nov., are described and illustrated. They are established based on fossil specimens with bodies and complete wings. All of them were collected from the late Middle Jurassic Jiulongshan Formation of Daohugou in southeastern Inner Mongolia,

Tingting Li; Dong Ren

2009-01-01

15

A NEW LATE JURASSIC TURTLE FROM SPAIN: PHYLOGENETIC IMPLICATIONS, TAPHONOMY AND  

E-print Network

A NEW LATE JURASSIC TURTLE FROM SPAIN: PHYLOGENETIC IMPLICATIONS, TAPHONOMY AND PALAEOECOLOGY.schouten@bristol.ac.uk Typescript received 26 October 2010; accepted in revised form 27 May 2011 Abstract: The Jurassic, and this is especially true of Jurassic turtles from Wes- tern Europe. A new genus and species of Late Jurassic turtle

Benton, Michael

16

A stratigraphic framework for Late Jurassic Early Cretaceous gas-bearing strata  

E-print Network

A stratigraphic framework for Late Jurassic­ Early Cretaceous gas-bearing strata (Monteith Formation) in the subsurface of northwest Alberta Abstract The entire Late Jurassic­Early Cretaceous stratal

17

2006 Nature Publishing Group A new carnivorous dinosaur from the Late Jurassic  

E-print Network

© 2006 Nature Publishing Group A new carnivorous dinosaur from the Late Jurassic Solnhofen archipelago Ursula B. Go¨hlich1 & Luis M. Chiappe2 Small Late Jurassic theropod dinosaurs are rare worldwide,2 , neither of which is well preserved. Here we describe a small new theropod dinosaur from the Late Jurassic

Cai, Long

18

Middle Jurassic fossils of the genus Sharasargus from Inner Mongolia, China (Diptera: Archisargidae)  

Microsoft Academic Search

To date, only two species of the genus Sharasargus are known. These Upper Jurassic species were found in Mongolia and Kazakhstan, respectively. We herein describe two new species from the Middle Jurassic, which were found in Inner Mongolia, China. They are the oldest known fossils of this genus. A key to Sharasargus species is given.

Kuiyan ZHANG; Ding YANG; Dong REN

2008-01-01

19

Discovery of silicified lacustrine micro-fossils and stromatolites: Triassic-Jurassic Fundy Group, Nova Scotia  

Microsoft Academic Search

A unique assemblage of silicified invertebrate and algal fresh-water lake fossils has been discovered in the Scots Bay Formation at the top of the Triassic-Jurassic Fundy Group of the Fundy Basin in Nova Scotia. This is important because the basins of the eastern North American Triassic-Jurassic rift system have not yielded many invertebrate and algal fossils. These new finds will

1985-01-01

20

Tectonostratigraphy, Biostratigraphy, and Magnetostratigraphy of Late Triassic-Early Jurassic Red  

E-print Network

Tectonostratigraphy, Biostratigraphy, and Magnetostratigraphy of Late Triassic-Early Jurassic Red Brook Street, Box 1846, Providence Rl 02912, USA Late Triassic-Early Jurassic predominately continental red beds formed during the Triassic/Jurassic rifting of Pangeacrop out over large portions of northern

Olsen, Paul E.

21

TECTONICS, VOL. 5, NO. 7, PAGES 1089-1114, DECEMBER1986 THE LATE JURASSIC OBLIQUE COLLISIONAL  

E-print Network

TECTONICS, VOL. 5, NO. 7, PAGES 1089-1114, DECEMBER1986 THE LATE JURASSIC OBLIQUE COLLISIONAL configuration of SW Japan mainly reflects a late Jurassic-early Cretaceous orogeny. The region is divided is divided into a Jurassic olistostrome known as the Tanba zone and a hinterland area comprising continental

Paris-Sud XI, Université de

22

Late Jurassic Epiphyton-like cyanobacteria: Indicators of long-term episodic variation in marine bioinduced microbial calcification?  

E-print Network

Late Jurassic Epiphyton-like cyanobacteria: Indicators of long-term episodic variation in marine Epiphyton Late Jurassic Romania Epiphytaceans occur in Late Jurassic shallow-marine reef limestones, but their precise affinities remain elusive and the group may be heterogeneous. These Late Jurassic examples most

Riding, Robert

23

Short communication A new fossil genus of Mesosciophilidae (Diptera, Nematocera) with two new species from the Middle Jurassic of Inner Mongolia, China  

Microsoft Academic Search

A new genus within the family Mesosciophilidae, Jurasciophila gen. nov., with two new species, J. curvula gen. et sp. nov. and J. lepida gen. et sp. nov., are described and illustrated. They are established based on fossil specimens with bodies and complete wings. All of them were collected from the late Middle Jurassic Jiulongshan Formation of Daohugou in southeastern Inner

Tingting Li; Dong Ren

24

New discovery of Palaeontinid fossils from the Middle Jurassic in Daohugou, Inner Mongolia (Homoptera, Palaeontinidae)  

Microsoft Academic Search

Three new species of fossil Palaeontinidae are described from Daohugou Village, Inner Mongolia, China: Daohugoucossus shii sp. nov., D. parallelivenius sp. nov., D. lii sp. nov. The diagnosis of Daohugoucossus Wang, Zhang and Fang, 2006 is revised. These materials are the first complete fossil palaeontinids in the Middle Jurassic\\u000a of the world. Based on observation of these new specimens, Sc

Ying Wang; Dong Ren; ChungKun Shih

2007-01-01

25

The earliest fossil record of Panorpidae (Mecoptera) from the Middle Jurassic of China  

PubMed Central

Abstract The early history of Panorpidae (Mecoptera) is poorly known due to sparse fossil records. Up to date, only nine fossil species have been described, all from the Paleogene, except the Early Cretaceous Solusipanorpa gibbidorsa Lin, 1980. However, we suggest S. gibbidorsa is too incompletely preserved to permit even family classification. A new genus with two new species, Jurassipanorpa impunctata gen. et sp. n. and Jurassipanorpa sticta sp. n., are described based on four well-preserved specimens from the late Middle Jurassic Jiulongshan Formation of Daohugou, Inner Mongolia, China. These two new species are the earliest fossil records of Panorpidae. The new genus is erected based on a combination of forewing characters: both R1 and Rs1 with two branches, 1A reaching posterior margin of wing distad of the forking of Rs from R1, and no crossveins or only one crossvein between veins of 1A and 2A. In all four specimens, long and robust setae ranging from 0.09 to 0.38 mm in length and pointing anteriorly, are present on anal veins of forewings. The function of these setae is enigmatic. PMID:25152669

Ding, He; Shih, Chungkun; Bashkuev, Alexei; Zhao, Yunyun; Ren, Dong

2014-01-01

26

The earliest fossil record of Panorpidae (Mecoptera) from the Middle Jurassic of China.  

PubMed

The early history of Panorpidae (Mecoptera) is poorly known due to sparse fossil records. Up to date, only nine fossil species have been described, all from the Paleogene, except the Early Cretaceous Solusipanorpa gibbidorsa Lin, 1980. However, we suggest S. gibbidorsa is too incompletely preserved to permit even family classification. A new genus with two new species, Jurassipanorpa impunctata gen. et sp. n. and Jurassipanorpa sticta sp. n., are described based on four well-preserved specimens from the late Middle Jurassic Jiulongshan Formation of Daohugou, Inner Mongolia, China. These two new species are the earliest fossil records of Panorpidae. The new genus is erected based on a combination of forewing characters: both R1 and Rs1 with two branches, 1A reaching posterior margin of wing distad of the forking of Rs from R1, and no crossveins or only one crossvein between veins of 1A and 2A. In all four specimens, long and robust setae ranging from 0.09 to 0.38 mm in length and pointing anteriorly, are present on anal veins of forewings. The function of these setae is enigmatic. PMID:25152669

Ding, He; Shih, Chungkun; Bashkuev, Alexei; Zhao, Yunyun; Ren, Dong

2014-01-01

27

Page 1 of 45 Gigantism among Late Jurassic limulids: new ichnological evidence from  

E-print Network

Page 1 of 45 Accepted M anuscript 1 Gigantism among Late Jurassic limulids: new ichnological was discovered in Upper Jurassic limestones from the Causses Basin (Causse M�jean, Loz�re, France gigantic horseshoe crabs in the Jurassic of Western Europe, thus casting doubt on the postulated increase

28

New fossil palaeontinids (Hemiptera, Cicadomorpha, Palaeontinidae) from the Middle Jurassic of Daohugou, China  

Microsoft Academic Search

Wang, Y., Shih, C., Szwedo, J. & Ren, D. iFirst article. New fossil palaeontinids (Hemiptera, Cicadomorpha, Palaeontinidae) from the Middle Jurassic of Daohugou, China. Alcheringa, 1–12. ISSN 0311-5518.A new genus and species assigned to the extinct family Palaeontinidae, Synapocossus sciacchitanoae Wang, Shih & Ren, is described from the Middle Jurassic of Daohugou in Inner Mongolia, China. This new genus is

Ying Wang; Chungkun Shih; Jacek Szwedo; Dong Ren

2012-01-01

29

A New Fossil Lacewing Genus and Species from the Middle Jurassic of Inner Mongolia, China  

Microsoft Academic Search

A new fossil lacewing, Tenuosmylus brevineurus gen. et sp. nov., was collected from an outcrop of Middle Jurassic strata in the village of Daohugou, Inner Mongolia, China. The new genus is assigned to Gumillinae based on eleven defining char? acteristics of the subfamily. The affiliation of Tenuosmylus in? cluding other five genera of the subfamily is discussed. Our re? sult

Yongjie Wang; Zhiqi Liu; Dong Ren

2009-01-01

30

Strontium and carbon isotope stratigraphy of the Late Jurassic shallow marine limestone in western Palaeo-Pacific, northwest Borneo  

E-print Network

Strontium and carbon isotope stratigraphy of the Late Jurassic shallow marine limestone in western carbonate sec- tion within the Late Jurassic Bau Limestone at the SSF quarry in northwest Borneo, Malaysia Scotland and Russia, located in Boreal realm during the Late Jurassic. This suggests that either

Gilli, Adrian

31

The conchostracan subgenus Orthestheria (Migransia) from the Tacuarembó Formation (Late Jurassic-?Early Cretaceous, Uruguay) with notes on its geological age  

NASA Astrophysics Data System (ADS)

Conchostracans from the Tacuarembó Formation s.s. of Uruguay are reassigned to the subgenus Orthestheria (Migransia) Chen and Shen. They show more similarities to genera of Late Jurassic age in the Congo Basin and China than to those of Early Cretaceous age. On the basis of the character of the conchostracans, we suggest that the Tacuarembó Formation is unlikely to be older than Late Jurassic. It is probably Kimmeridgian, but an Early Cretaceous age cannot be excluded. This finding is consistent with isotopic dating of the overlying basalts, as well as the age range of recently described fossil freshwater sharks.

Yanbin, Shen; Gallego, Oscar F.; Martínez, Sergio

32

Detailed record of the mid-Oxfordian (Late Jurassic) positive carbon-isotope excursion in two hemipelagic sections (France  

E-print Network

Detailed record of the mid-Oxfordian (Late Jurassic) positive carbon-isotope excursion in two 2007 Abstract The Oxfordian (Late Jurassic) was a time of widespread change in Jurassic marine coincide with the first calcareous sediments recurring after a period of reduced carbonate accumulation

Gilli, Adrian

33

The Zedong terrane: a Late Jurassic intra-oceanic magmatic arc within the YarlungTsangpo suture zone, southeastern Tibet  

E-print Network

The Zedong terrane: a Late Jurassic intra-oceanic magmatic arc within the Yarlung­Tsangpo suture microprobe analyses reported here reveal that this arc was active during the Jurassic. U­ Pb dating of zircon belonged was active from at least Late Jurassic to Early to mid Cretaceous. D 2002 Published by Elsevier

Harrison, Mark

34

Chasing the Late Jurassic APW Monster Shift in Ontario Kimberlites  

NASA Astrophysics Data System (ADS)

A 30° gap was recognized in a composite APW path when global poles from predominantly igneous rocks were assembled in North American coordinates using plate reconstructions (Kent & Irving 2010 JGR). The 'monster shift' occurred between a 160-190 Ma cluster of mean poles at 75-80°N 90-110°E to a 140-145 Ma grouping centered at 60-65°N ~200°E. There are hardly any intermediate igneous poles whereas the rather divergent directions from the Late Jurassic Morrison Formation published by Steiner & Helsley (1975 GSA Bulletin) are subject to adjustments for Colorado Plateau rotation and sedimentary inclination error, neither of which are precisely known for this redbed unit sampled in Colorado. On the other hand, similar large rapid swings have been recognized in the Late Jurassic APW path for Adria (Channell et al. 2010 Paleo3), suggesting a global phenomena. In an effort to fill the data gap between ~145 and 160 Ma, we sampled accessible outcrops/subcrops of kimberlites in the Timiskaming area of Ontario, Canada, that are associated with high precision U-Pb perovskite ages (Heamon & Kjarsgaard 2000 EPSL). We report initial results from two of the intrusions: the 153.6±2.4 Ma Peddie kimberlite from outcrop and the Triple B kimberlite that was accessible by trenching and is assumed to be the same age as the nearby 153.7±1.8 Ma Seed kimberlite as delineated by aeromagnetic surveys and borings. Systematic progressive thermal demagnetization indicated in each unit a dominant characteristic component with unblocking temperatures to 575° that presumably reflect a magnetite carrier that will be checked by further rock magnetic experiments. Samples from the Peddie kimberlite had stable downward (normal polarity) magnetizations whose mean direction gives a paleopole at 73°N 184°E. In contrast, samples from the Triple B kimberlite have upward (reverse polarity) magnetizations with a well-grouped direction whose (north) paleopole is 78°N 197°E, proximal to the Peddie pole. The normal and reverse polarities suggest that sufficient time elapsed between emplacement of the Triple B and Peddie to give an opportunity to average secular variation. The combined ~154 Ma Triple B and Peddie pole encouragingly lies about halfway between igneous poles from North America nearest in age: the 169 Ma Moat volcanics and the 142 Ma Ithaca kimberlites. However, preliminary paleomagnetic results from some of the other sampled kimberlite bodies are more problematical and require further paleomagnetic and geochronological work.

Kent, D. V.; Muttoni, G.; Gee, J. S.; Kjarsgaard, B. A.

2012-12-01

35

New fossil elaterids (Insect: Coleoptera: Polyphaga: Elateridae) from the Middle Jurassic of Inner Mongolia, China  

Microsoft Academic Search

A new genus with a new species of fossil elaterid, Paraprotagrypnus superbus gen. et sp. nov., from the Middle Jurassic Jiulongshan Formation in Daohugou Village (N41°18.979?, E119°14.318?), Shantou Township, Ningcheng County, Inner Mongolia, China is described and illustrated. The genus Paraprotagrypnus belongs to the family of Elateridae, subfamily of Protagrypninae and tribe of Protagrypnini. Some primitive characters of the new

Huali Chang; Yunyun Zhao; Dong Ren

2009-01-01

36

Porosity controls in Late Jurassic algal reefs, Mississippi salt basin  

SciTech Connect

Reefs associated with high-rise salt structures that were active during Late Jurassic deposition (Smackover-Haynesville) have been the target of numerous deep tests in the Mississippi Salt basin. One such test, in Wayne County, Mississippi, encountered a 24-m reef. The reef exhibited no porosity or permeability, while sequences above (21 m) and below (24 m) were dolomitized, porous, and permeable. The reef sequence consists of a facies mosaic of encrusting to columnar massive red coralline algae, laminated to stromatolitic blue-green algae(.) with associated pelleted internal sediments and other features characteristic of modern framework reefs. The reef complex exhibits a strong early marine diagenetic overprint consisting of bladed to fibrous magnesian calcite(.) cements and botryoidal masses of magnesian calcite or aragonite. The lack of discernible freshwater diagenesis and the nature of the reef framework seem to indicate deeper water conditions for reef development and subsequent early diagenesis. The associated dolomites have relict texture indicating that they were originally grainstones, perhaps derived from the reef itself. In the reef sequence, the geologic setting (relatively deep water), early marine cementation, and encrusting nature of the reef-formers produced a non-porous rock which was not susceptible to early dolomitization. However, the associated porous grainstones allowed active circulation of dolomitizing fluids (marine water.), leading to total dolomitization and a favorable reservoir facies.

Heydari, E.; Moore, C.H.

1987-05-01

37

Late Jurassic-Early Cretaceous evolution of the eastern Indian Ocean adjacent to northwest Australia  

E-print Network

LATE JURASSIC-EARLY CRETACEOUS EVOLUTION OF THE EASTERN INDIAN OCEAN ADJACENT TO NORTHWEST AUSTRALIA A Thesis by LAWRENCE GILLIAM FULLERTON Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE December 1987 Major Subject: Oceanography LATE JURASSIC-EARLY CRETACEOUS EVOLUTION OF THE EASTERN INDIAN OCEAN ADJACENT TO NORTHWEST AUSTRALIA A Thesis by LAWRENCE GILLIAM FULLERTON Approved as to style and content by...

Fullerton, Lawrence Gilliam

2012-06-07

38

Late Triassic-Jurassic paleogeography and origin of Gulf of Mexico basin  

SciTech Connect

The basic structural and stratigraphic framework of the Gulf of Mexico Basin was established during the Late Triassic and the Jurassic. During the Late Triassic and Early Jurassic, as the North American plate started to separate from the South American and African plates, the area of the future basin was part of an extensive landmass broken by tensional grabens that were filled by red beds and volcanics. Marine deposition was restricted to embayments of the Pacific Ocean in northwestern and central Mexico. These marine embayments persisted during the early Middle Jurassic, but seawater did not reach the future Gulf of Mexico Basin until the Callovian. Widespread salt deposits known today from two separate areas of the basin resulted from this initial flooding. During the Late Jurassic, marine conditions progressively extended over increasingly larger parts of the Gulf of Mexico Basin. However, the basin was not connected to the Atlantic Ocean until late in the Jurassic. This paleogeographic reconstruction suggests that the Gulf of Mexico Basin formed as a result of the southward drift of the Yucatan continental block away from the remainder of the North American plate. The separation began in the Late Triassic, continued slowly and sporadically during the Early and Middle Jurassic, and quickened after the Middle Jurassic salt formed. As a result, the salt deposits were split into the two segments known today, and oceanic crust formed in the center of the basin. Early in the Late Jurassic, the Yucatan platform reached its present position and the Gulf of Mexico Basin was born. 14 figures.

Salvador, A.

1987-04-01

39

A revised time scale of magnetic reversals for the Early Cretaceous and Late Jurassic  

Microsoft Academic Search

A magnetic reversal block model for the Early Cretaceous-Late Jurassic period was developed from four closely spaced profiles across the Hawaiian lineation pattern by Hilde (1973) and Hilde el al. (1974). Larson (1974) independently developed an improved model of this reversal period by reanalyzing the data presented by Larson and Chase (1972) plus a profile collected during Deep Sea Drilling

Roger L. Larson; Thomas W. C. Hilde

1975-01-01

40

Short communication New fossil elaterids (Insect: Coleoptera: Polyphaga: Elateridae) from the Middle Jurassic of Inner Mongolia, China  

Microsoft Academic Search

A new genus with a new species of fossil elaterid, Paraprotagrypnus superbus gen. et sp. nov., from the Middle Jurassic Jiulongshan Formation in Daohugou Village (N4118.979 0 , E11914.318 0 ), Shantou Township, Ningcheng County, Inner Mongolia, China is described and illustrated. The genus Paraprotagrypnus belongs to the family of Elateridae, subfamily of Protagrypninae and tribe of Prota- grypnini. Some

Huali Chang; Yunyun Zhao; Dong Ren

2009-01-01

41

Late Jurassic weather forecast, Four Corners area: Dry, hot, and partly sunny  

SciTech Connect

Interfingering between members of the Upper Jurassic Morrison Formation and inferences based on their various environments of deposition permit interpretation of a persistent paleoclimate during the Late Jurassic in the Colorado Plateau region. Paleoclimate interpretation is based on evaporites in the Tidwell member, at the base of the Morrison; eolian deposits in the Recapture and Bluff Sandstone members; and saline, alkaline-lake deposits (which indicate high evaporation rates) in the Brushy Basin member at the top of the Morrison. Interfingering of these members with all other members of the Morrison Formation implies that a semiarid to arid climate was likely throughout Morrison time. The semiarid to arid interpretation is consistent with the global climatic zone inferred from the paleogeographic/paleotectonic setting. The Four Corners area during the Late Jurassic was in the middle latitudes of the Northern Hemisphere and thus was affected by prevailing westerly winds. A magmatic arc located several hundred kilometers to the west of the Morrison depositional basin may have caused a broad rain-shadow effect, which contributed to a dry continental climate downwind. A typical Late Jurassic day in the Four Corners area is predicted to have been hot and dry, although seasonally heavy rains probably fed intermittent streams that transported sediments into the region. Explosive eruptions of silicic volcanic ash may have darkened the skies episodically, and thus partly sunny would have been a conservative forecast.

Turner-Peterson, C.E.; Fishman, N.S. (Geological Survey, Denver, CO (USA))

1989-09-01

42

Mass extinctions in the fossil record of late Palaeozoic and Mesozoic tetrapods  

NASA Astrophysics Data System (ADS)

The fossil record of tetrapods is very patchy because of the problems of preservation in terrestrial sediments, and because vertebrates are rarely very abundant. However, the fossil record of tetrapods has the advantages that it is easier to establish a phylogenetic taxonomy than for many invertebrate groups (many characters; fast evolution), and there is the potential for more detailed ecological analyses (greater knowledge of modern tetrapod ecology). The diversity of tetrapods increased during the Devonian, the Carboniferous, and the Permian, but it remained generally constant during the Triassic, the Jurassic, and the Early Cretaceous. Overall diversity then began to increase in the Late Cretaceous, and continued to do so during the Tertiary. The rapid radiation of modern tetrapod groups — frogs, salamanders, lizards, snakes, turtles, crocodiles, birds and mammals — was hardly affected by the celebrated end-Cretaceous extinction event.

Benton, Michael J.

43

A taxonomic review of the Late Jurassic eucryptodiran turtles from the Jura Mountains (Switzerland and France).  

PubMed

Background. Eucryptodiran turtles from the Late Jurassic (mainly Kimmeridgian) deposits of the Jura Mountains (Switzerland and France) are among the earliest named species traditionally referred to the Plesiochelyidae, Thalassemydidae, and Eurysternidae. As such, they are a reference for the study of Late Jurassic eucryptodires at the European scale. Fifteen species and four genera have been typified based on material from the Late Jurassic of the Jura Mountains. In the past 50 years, diverging taxonomic reassessments have been proposed for these turtles with little agreement in sight. In addition, there has been a shift of focus from shell to cranial anatomy in the past forty years, although most of these species are only represented by shell material. As a result, the taxonomic status of many of these 15 species remains ambiguous, which prevents comprehensive comparison of Late Jurassic turtle assemblages throughout Europe and hinders description of new discoveries, such as the new assemblage recently unearthed in the vicinity of Porrentruy, Switzerland. Methods. An exhaustive reassessment of the available material provides new insights into the comparative anatomy of these turtles. The taxonomic status of each of the 15 species typified based on material from the Late Jurassic of the Jura Mountains is evaluated. New diagnoses and general descriptions are provided for each valid taxon. Results. Six out of the 15 available species names are recognized as valid: Plesiochelys etalloni, Craspedochelys picteti, Craspedochelys jaccardi, Tropidemys langii, Thalassemys hugii, and 'Thalassemys' moseri. The intraspecific variability of the shell of P. etalloni is discussed based on a sample of about 30 relatively complete specimens from Solothurn, Switzerland. New characters are proposed to differentiate P. etalloni, C. picteti, and C. jaccardi, therefore rejecting the previously proposed synonymy of these forms. Based partly on previously undescribed specimens, the plastral morphology of Th. hugii is redescribed. The presence of lateral plastral fontanelles is notably revealed in this species, which calls into question the traditional definitions of the Thalassemydidae and Eurysternidae. Based on these new data, Eurysternum ignoratum is considered a junior synonym of Th. hugii. The Eurysternidae are therefore only represented by Solnhofia parsonsi in the Late Jurassic of the Jura Mountains. Finally, 'Th.' moseri is recognized as a valid species, although a referral to the genus Thalassemys is refuted. PMID:24883240

Anquetin, Jérémy; Püntener, Christian; Billon-Bruyat, Jean-Paul

2014-01-01

44

Late Jurassic low latitude of Central Iran: paleogeographic and tectonic implications  

NASA Astrophysics Data System (ADS)

The individual blocks forming present-day Central Iran are now comprised between the Zagros Neo-Tethys suture to the south and the Alborz Palaeo-Tethys suture to the north. At the end of the Palaeozoic, the Iranian blocks rifted away from the northern margin of Gondwana as consequence of the opening of the Neo-Tethys, and collided with Eurasia during the Late Triassic, giving place to the Eo-Cimmerian orogeny. From then on, the Iranian block(s) should have maintained European affinity. Modern generations of apparent polar wander paths (APWPs) show the occurrence in North American and African coordinates of a major and rapid shift in pole position (=plate shift) during the Middle-Late Jurassic. This so-called monster polar shift is predicted also for Eurasia from the North Atlantic plate circuit, but Jurassic data from this continent are scanty and problematic. Here, we present paleomagnetic data from the Kimmeridgian-Tithonian (Upper Jurassic) Garedu Formation of Iran. Paleomagnetic component directions of primary (pre-folding) age indicate a paleolatitude of deposition of 10°N ± 5° that is in excellent agreement with the latitude drop predicted for Iran from APWPs incorporating the Jurassic monster polar shift. We show that paleolatitudes calculated from these APWPs, used in conjunction with simple zonal climate belts, better explain the overall stratigraphic evolution of Iran during the Mesozoic.

Mattei, Massimo; Muttoni, Giovanni; Cifelli, Francesca

2014-05-01

45

Trace Fossil Evidence for Late Ordovician Animals on Land  

Microsoft Academic Search

Fossil burrows within newly recognized buried soils in the Late Ordovician Juniata Formation, near Potters Mills in central Pennsylvania, represent the oldest reported nonmarine trace fossils. They are thought to have been an original part of the soil because their greater density toward the top of the paleosols corresponds with mineralogical, microstructural, and chemical changes attributed to ancient weathering and

Gregory J. Retallack; Carolyn R. Feakes

1987-01-01

46

Problematic fossils in the late Neoproterozoic Wonoka Formation, South Australia  

Microsoft Academic Search

Complex biogenic structures are described from the upper Wonoka Formation (late Neoproterozoic) of the Adelaide ‘Geosyncline’, South Australia. The structures are preserved within silty limestones and calcareous siltstones as dark bedding plane markings defining branching arrays of parallel, elongate, curved elements. The fossils bear at least a superficial resemblance to the putative trace fossil Palaeopascichnus, normally preserved in siliciclastic sediments,

Peter W. Haines

2000-01-01

47

Vertebrate fossils from late Cenozoic deposits of central Kansas  

E-print Network

UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS VERTEBRATA ARTICLE 2 Pages 1-14, Figures 1-14 VERTEBRATE FOSSILS FROM LATE CENOZOIC DEPOSITS OF CENTRAL KANSAS By CLAUDE W. HIBBARD UNIVERS= OF KANSAS PUBLICATIONS MARCH 20, 1952 PRINTED BY FERD... VOILAND, JR.. STATE PRINTER TOPEKA. KANSAS 1952 24-975 UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS VERTEBRATA, ARTICLE 2, PAGES 1-14, FIGLTRES 1-14 VERTEBRATE FOSSILS FROM LATE CENOZOIC DEPOSITS OF CENTRAL KANSAS By CLAUDE W. HIBBARD CONTENTS PAGE...

Hibbard, C. W.

1952-03-20

48

Oxfordian-Kimmeridgian (Late Jurassic) reservoir sandstones in the Witch Ground Graben, U. K. North Sea  

SciTech Connect

Oil-bearing Late Jurassic Oxfordian-Kimmeridgian sandstones of the Sgiath and Piper formations are of major economic importance in the Witch Ground Graben. They form the reservoirs in Scott, which in 1993 will be the largest producing North Sea oil field to come on stream for more than a decade. Together with Scott, the Piper, Saltire, Tartan, Highlander, Petronella, Rob Roy, and Ivanhoe fields contained almost 2 Bbbl of recoverable reserves in these formations. The Sgiath and Piper represent two phases of Late Jurassic transgression and regression, initially represented by paralic deposited sand culminating in a wave-dominated delta sequence. The history of the Sgiath and Piper formations is reviewed and lithostratigraphic and biostratigraphic correlations presented to illustrate the distribution of the reservoir sandstones.

Harker, S.D. (Occidental Petroleum (Caledonia) Ltd., Aberdeen (United Kingdom)); Mantel, K.A. (Narwhal, London (United Kingdom)); Morton, D.J. (Deminex U.K. Oil and Gas Ltd., London (United Kingdom)); Riley, L.A. (Paleoservices, Watford (United Kingdom))

1991-03-01

49

Chemostratigraphic Constraints on Late Jurassic Paleoceanography of the East Texas Basin, Southern Margin of North America  

Microsoft Academic Search

Late Jurassic deposition of organic-rich muds occurred in the East Texas Basin of modern-day Texas and Louisiana in a ramp-style marine setting during the early formation of the Gulf of Mexico. These mudrocks are regional known as the Haynesville and Bossier Formations. The goals of the current project are to 1) develop a better understanding of the paleoceanographic conditions and

P. Mainali; H. D. Rowe

2010-01-01

50

Discovery of a Late Jurassic Chinese mammal in the Upper Bathonian of England  

NASA Astrophysics Data System (ADS)

The Forest Marble Formation of England, Upper Bathonian, has provided a large collection of mammalian teeth, among which at least five lower molars can be attributed to the genus Shuotherium, previously known by a single jaw from the Late Jurassic of China. Moreover, three upper molars are tentatively referred to this taxon, confirming the presence of a 'protocone' in the molars of this member of a highly and precociously derived therian clade.

Sigogneau-Russell, Denise

1998-10-01

51

Palaeobiogeographic implications of Late Bajocian-Late Callovian (Middle Jurassic) dinoflagellate cysts from the Central Alborz Mountains, northern Iran  

NASA Astrophysics Data System (ADS)

The Dalichai Formation with an age of Late Bajocian-Late Callovian was sampled in Central Alborz Mountains of northern Iran and studied for palynological, palaeobiogeographical and palynocorrelation purposes. Palynological studies revealed diverse and well-preserved dinoflagellate cyst assemblages and lead to identification of three zones i.e., Cribroperidiniumcrispum (Late Bajocian), Dichadogonyaulaxsellwoodii (Bathonian to Early Callovian) and Ctenidodiniumcontinuum (Early to Middle Callovian) Zones. Subzone a of the D. sellwoodii Zone (Early to Middle Bathonian) was also differentiated. This biozonation corresponds to those recognised in Northwest Europe. Furthermore, the ammonoid families recorded including Phylloceratidae, Oppeliidae, Reineckeiidae, Perisphinctidae, Haploceratidae, Parkinsoniidae and Sphaeroceratidae, which confirm the Late Bajocian to Late Callovian age, are quite similar to those of Northwest Europe and the northwestern Tethys. The close similarities of the dinoflagellate cyst assemblages and ammonite fauna of northern Iran with those of Northwest Europe and the northwestern Tethys during the Middle Jurassic indicate direct but episodic marine connection and faunal exchange between the two areas.

Ghasemi-Nejad, Ebrahim; Sabbaghiyan, Hossein; Mosaddegh, Hossein

2012-01-01

52

Fossils from the Middle Jurassic of China shed light on morphology of Choristopsychidae (Insecta, Mecoptera).  

PubMed

Choristopsychidae, established by Martynov in 1937 with a single isolated forewing, is a little known extinct family in Mecoptera. Since then, no new members of this enigmatic family have been described. Based on 23 well-preserved specimens with complete body and wings from the Middle Jurassic of northeastern China, we report one new genus and three new species of Choristopsychidae, two new species of the genus Choristopsyche Martynov, 1937: Choristopsyche perfecta sp. n. and Choristopsyche asticta sp. n.; one new species of Paristopsyche gen. n.: Paristopsyche angelineae sp. n.; and re-describe Choristopsyche tenuinervis Martynov, 1937. In addition, we emend the diagnoses of Choristopsychidae and Choristopsyche. Analyzing the forewing length/width ratios of representative species in Mecoptera, we confirm that choristopsychids have the lowest ratio of forewing length/width, meaning broadest forewings. These findings, the first fossil choristopsychids with well-preserved body structure and the first record of Choristopsychidae in China, shed light on the morphology of these taxa and broaden their distribution from Tajikistan to China, while increasing the diversity of Mesozoic Mecoptera in China. PMID:23950679

Qiao, Xiao; Shih, Chung Kun; Petrulevi?ius, Julian F; Dong, Ren

2013-01-01

53

Discovery of a short-necked sauropod dinosaur from the Late Jurassic period of Patagonia.  

PubMed

Sauropod dinosaurs are one of the most conspicuous groups of Mesozoic terrestrial vertebrates. They show general trends towards an overall increase in size and elongation of the neck, by means of considerable elongation of the length of individual vertebrae and a cervical vertebra count that, in some cases, increases to 19 (ref. 1). The long neck is a particular hallmark of sauropod dinosaurs and is usually regarded as a key feeding adaptation. Here we describe a new dicraeosaurid sauropod, from the latest Jurassic period of Patagonia, that has a particularly short neck. With a neck that is about 40% shorter than in other known dicraeosaurs, this taxon demonstrates a trend opposite to that seen in most sauropods and indicates that the ecology of dicraeosaurids might have differed considerably from that of other sauropods. The new taxon indicates that there was a rapid radiation and dispersal of dicraeosaurids in the Late Jurassic of the Southern Hemisphere, after the separation of Gondwana from the northern continents by the late Middle Jurassic. PMID:15931221

Rauhut, Oliver W M; Remes, Kristian; Fechner, Regina; Cladera, Gerardo; Puerta, Pablo

2005-06-01

54

A total petroleum system of the Browse Basin, Australia; Late Jurassic, Early Cretaceous-Mesozoic  

USGS Publications Warehouse

The Browse Basin Province 3913, offshore northern Australia, contains one important petroleum system, Late Jurassic, Early Cretaceous-Mesozoic. It is comprised of Late Jurassic through Early Cretaceous source rocks deposited in restricted marine environments and various Mesozoic reservoir rocks deposited in deep-water fan to fluvial settings. Jurassic age intraformational shales and claystones and Cretaceous regional claystones seal the reservoirs. Since 1967, when exploration began in this 105,000 km2 area, fewer than 40 wells have been drilled and only one recent oil discovery is considered potentially commercial. Prior to the most recent oil discovery, on the eastern side of the basin, a giant gas field was discovered in 1971, under a modern reef on the west side of the basin. Several additional oil and gas discoveries and shows were made elsewhere. A portion of the Vulcan sub-basin lies within Province 3913 where a small field, confirmed in 1987, produced 18.8 million barrels of oil (MMBO) up to 1995 and has since been shut in.

Bishop, M. G.

1999-01-01

55

A depositional model for late Jurassic Reef Building in the East Texas Basin  

SciTech Connect

The authors propose a depositional setting for the Upper Jurassic reef facies occurring at the upper Cotton Valley Lime, (Gilmer) sequence boundary in the East Texas Basin. The development of uncommonly thick, microbially bound reefal buildups positioned near the western margin of the basin was controlled by sea-level variations and gravity faulting, suggested to be concurrent. Gas bearing reefs occur as isolated features along faulted margins and have been successfully located using 3-D seismic. Reefs of this type and age appear to be rare in their occurrence worldwide. Structurally generated circumstances facilitated margin bypass of terrigenous clastics shed from the north and west. Protection from clastic influx contributed to conditions required for development of the 400 feet of reefal buildup penetrated by the Marathon Oil Company Poth No. 1 during early 1993. Core from this well provides insight into character, composition, and depositional setting of reefs along the western flank of the East Texas Basin during Late Jurassic time.

Norwood, E.M. (Marathon Oil Co., Tyler, TX (United States)); Brinton, L. (Marathon Oil Co., Littleton, CO (United States))

1996-01-01

56

A depositional model for late Jurassic Reef Building in the East Texas Basin  

SciTech Connect

The authors propose a depositional setting for the Upper Jurassic reef facies occurring at the upper Cotton Valley Lime, (Gilmer) sequence boundary in the East Texas Basin. The development of uncommonly thick, microbially bound reefal buildups positioned near the western margin of the basin was controlled by sea-level variations and gravity faulting, suggested to be concurrent. Gas bearing reefs occur as isolated features along faulted margins and have been successfully located using 3-D seismic. Reefs of this type and age appear to be rare in their occurrence worldwide. Structurally generated circumstances facilitated margin bypass of terrigenous clastics shed from the north and west. Protection from clastic influx contributed to conditions required for development of the 400 feet of reefal buildup penetrated by the Marathon Oil Company Poth No. 1 during early 1993. Core from this well provides insight into character, composition, and depositional setting of reefs along the western flank of the East Texas Basin during Late Jurassic time.

Norwood, E.M. [Marathon Oil Co., Tyler, TX (United States); Brinton, L. [Marathon Oil Co., Littleton, CO (United States)

1996-12-31

57

Geophysical Evidence for a Possible Late Jurassic Mantle Plume in the Gulf of Mexico  

NASA Astrophysics Data System (ADS)

Gravity, magnetic and seismic refraction data reveal a prominent basement structure beneath the Keathley Canyon area of the western Gulf of Mexico. Several seismic refraction profiles acquired near and over the structure indicate depths to its crest range from 10.5 to 12 km, rising from basement depths of 14 to 16 km below sea level. Because of the presence of extensive salt features, seismic reflection data are unable to accurately image the structure but several reflection profiles indicate the existence of a basement high in the area. A positive free-air gravity anomaly associated with this basement structure extends 200 km from 93.9o W, 26.4o N along a roughly WNW-ESE directed path to 91.7o W, 25.9o N where it turns northeastward. Bathymetric and seismic reflection data indicate the gravity anomaly is not produced by seafloor topography or shallow sedimentary sources, but can be attributed to the basement relief documented. Its amplitude and wavelength decrease to the ESE, from 70 mGal and 100 km wavelength to 35 mGal and 40 km wavelength. A positive magnetic anomaly with a 130 nT amplitude and 30 km wavelength coincides with the WNW end of the free air gravity anomaly. It extends to the ESE in a similar manner to the gravity anomaly, but its amplitude decays more rapidly. Most models for the formation of the Gulf of Mexico basin culminate in a late Jurassic-early Cretaceous phase of seafloor spreading as the Yucatan Block rotates counterclockwise away from North America. The shape of the free air gravity anomaly over the deep basement structure defines a geometry that is similar to those produced by other hotspot tracks, such as the New England Seamounts, Rio Grande Rise or Vitoria-Trindade seamount chain. The WNW-ESE direction is broadly consistent with motion of North America in the hotspot reference frame at the time of basin formation. Such an interpretation suggests that a minor mantle plume may have been active during spreading and played a significant role in the development of the basin. We consider the westerly end of the gravity anomaly to roughly delineate the ocean-continent boundary beneath >15 km of sediments off the Texas coast. At its eastern end, the gravity anomaly turns northeastward and may correspond to the location of a fossil sea floor spreading center.

Bird, D. E.; Hall, S. A.; Casey, J. F.; Burke, K.

2001-12-01

58

The generation of high Sr\\/Y plutons following Late Jurassic arc-arc collision, Blue Mountains province, NE Oregon  

Microsoft Academic Search

High Sr\\/Y plutons (Sr\\/Y > 40) occupy large areas in ancient and modern orogenic belts, yet considerable controversy exists regarding mechanisms of their generation, the tectonic settings in which they form, and their relationship to contractional deformation through time. In the Blue Mountains province (NE Oregon), a suite of Late Jurassic (148-145 Ma), high Sr\\/Y plutons intrude Middle Jurassic (162-157

Joshua J. Schwartz; Kenneth Johnson; Elena A. Miranda; Joseph L. Wooden

2011-01-01

59

The generation of high Sr\\/Y plutons following Late Jurassic arc–arc collision, Blue Mountains province, NE Oregon  

Microsoft Academic Search

High Sr\\/Y plutons (Sr\\/Y>40) occupy large areas in ancient and modern orogenic belts, yet considerable controversy exists regarding mechanisms of their generation, the tectonic settings in which they form, and their relationship to contractional deformation through time. In the Blue Mountains province (NE Oregon), a suite of Late Jurassic (148–145Ma), high Sr\\/Y plutons intrude Middle Jurassic (162–157Ma), low Sr\\/Y (<40)

Joshua J. Schwartz; Kenneth Johnson; Elena A. Miranda; Joseph L. Wooden

2011-01-01

60

Fossil woods from the Late Cretaceous Aachen Formation  

Microsoft Academic Search

Silicified fossil woods from the Late Cretaceous (Santonian) Aachen Formation of northeast Belgium, southernmost Netherlands and adjacent Germany were investigated. Gymnosperms dominate this assemblage: Taxodioxylon gypsaceum, T. cf. gypsaceum, T. cf. albertense (all Taxodiaceae), Dammaroxylon aachenense sp. nov. (Araucariaceae), Pinuxylon sp. (Pinaceae), and Scalaroxylon sp. (Cycad or Cycadeoid). Angiosperms are minor constituents: Nyssoxylon sp. (Nyssaceae?, Cornaceae?), Mastixioxylon symplocoides sp. nov.

Jacques J. F. Meijer

2000-01-01

61

Trace fossil evidence for late ordovician animals on land.  

PubMed

Fossil burrows within newly recognized buried soils in the Late Ordovician Juniata Formation, near Potters Mills in central Pennsylvania, represent the oldest reported nonmarine trace fossils. They are thought to have been an original part of the soil because their greater density toward the top of the paleosols corresponds with mineralogical, microstructural, and chemical changes attributed to ancient weathering and because about half the burrows are encrusted with nodular carbonate, interpreted as caliche. Associated fossil caliche, the size distribution of the burrows, and their W-shaped backfills are evidence that the burrows may have been excavated by bilaterally symmetrical organisms that grew in well-defined growth increments and were able to withstand desiccation. Among well-known soil organisms, millipedes are burrowing animals that satisfy these requirements, but have a fossil record not quite this old. This trace fossil evidence for animals on land, together with recent palynological evidence for land plants of a bryophytic grade of evolution during Late Ordovician time, are indications of terrestrial ecosystems of slightly greater antiquity and complexity than hitherto suspected. PMID:17769314

Retallack, G J; Feakes, C R

1987-01-01

62

Late Jurassic ocean anoxic event: evidence from voluminous sulphide deposition and preservation in the Panthalassa.  

PubMed

The historically productive copper-bearing Besshi-type sulphide deposits in the Japanese accretionary complex were formed as volcanogenic massive sulphide deposits on the deep-sea floor of the Panthalassa Ocean. Here we report that eleven typical Besshi-type deposits yielded Re-Os isochron ages around 150 Ma (148.4 ± 1.4 Ma from the composite isochron) in Late Jurassic time. This date coincides with the lowest marine (87)Sr/(86)Sr ratio and highest atmospheric CO2 concentration of the past 300 million years. We infer that intense mid-ocean ridge hydrothermal and volcanic activity in the Late Jurassic produced huge sulphide deposits and large emissions of CO2 gas, leading to global warming and a stratified Panthalassa Ocean with anoxic deep seas that favored preservation of sulphides in the pelagic environment. The emergence of ocean anoxia triggered by seafloor volcanism is also consistent with a positive ?(13)C excursion and widespread deposition of petroleum source rocks and black shales. PMID:23712471

Nozaki, Tatsuo; Kato, Yasuhiro; Suzuki, Katsuhiko

2013-01-01

63

The rediscovery and redescription of the holotype of the Late Jurassic turtle Plesiochelys etalloni.  

PubMed

Plesiochelyidae are a major component of Late Jurassic shallow marine environments throughout Europe. However, the taxonomy of plesiochelyid turtles is rather confused. Over the years, many taxa have been synonymized with Plesiochelys etalloni, one of the first described species. However, the holotype of P. etalloni (and only specimen known from Lect, the type locality) was lost for more than 150 years. This specimen has been recently rediscovered in the collections of the Musée d'archéologie du Jura in Lons-le-Saunier, France. For the first time since its original description in 1857, the holotype of P. etalloni is redescribed and compared to relevant material. The taxonomic status of this taxon is revised accordingly. Based on the morphology of the newly rediscovered holotype and on a reassessment of specimens from Solothurn (Switzerland), the species P. solodurensis, P. sanctaeverenae and P. langii are synonymized with P. etalloni. Known skull-shell associations for P. etalloni are re-evaluated in light of the new morphological information available since the rediscovery of this holotype specimen. Finally, we confirm that Plesiochelys is represented by a single species in the Late Jurassic of the Jura Mountains. PMID:24688842

Anquetin, Jérémy; Deschamps, Sylvie; Claude, Julien

2014-01-01

64

A new fossil from the Jurassic of Patagonia reveals the early basicranial evolution and the origins of Crocodyliformes.  

PubMed

Extant crocodylians have a limited taxonomic and ecological diversity but they belong to a lineage (Crocodylomorpha) that includes basal and rather generalized species and a highly diverse clade, Crocodyliformes. The latter was among the most successful groups of Mesozoic tetrapods, both in terms of taxonomic and ecological diversity. Crocodyliforms thrived in terrestrial, semiaquatic, and marine environments, and their fossil diversity includes carnivorous, piscivorous, insectivorous, and herbivorous species. This remarkable ecological and trophic diversity is thought only to occur in forms with a completely akinetic skull, characterized by a functionally integrated and tightly sutured braincase-quadrate-palate complex. However, the patterns of evolutionary change that led to the highly modified skull of crocodyliforms and that likely enabled their diversification remain poorly understood. Herein, a new basal crocodylomorph from the Late Jurassic of Patagonia is described, Almadasuchus figarii gen. et sp. nov. The new taxon is known from a well-preserved posterior region of the skull as well as other craniomandibular and postcranial remains. Almadasuchus figarii differs from all other crocodylomorphs in the presence of six autapomorphic features, including the presence of a large lateral notch on the upper temporal bar, an otic shelf of the squamosal that is wider than long, a deep subtriangular concavity on the posterolateral surface of the squamosal, and an elongated pneumatopore on the ventral surface of the quadrate. Phylogenetic analysis focused on the origin of Crocodyliformes places Almadasuchus as the sister group of Crocodyliformes, supported by synapomorphic features of the skull (e.g. subtriangular basisphenoid, absence of basipterygoid process, absence of a sagittal ridge on the frontal, and a flat anterior skull roof with an ornamented dorsal surface). New braincase information provided by Almadasuchus and other crocodylomorphs indicates that most of the modifications on the posterior region of the skull of crocodyliforms, including the strongly sutured braincase, quadrate, and the extensive secondary palate appeared in a stepwise manner, and pre-dated the evolutionary changes in the snout, jaws, and dentition. This indicates that the progressively increased rigidity of the skull provided the structural framework that allowed the great ecological diversification of crocodyliforms during the course of the Mesozoic. The phylogenetic pattern of character acquisition inferred for the strongly sutured (akinetic) skull and the appearance of more diverse feeding behaviours that create high mechanical loads on the skull provides another interesting parallel between the evolution of Mesozoic crocodyliforms and the evolutionary origins of mammals. PMID:23445256

Pol, Diego; Rauhut, Oliver W M; Lecuona, Agustina; Leardi, Juan M; Xu, Xing; Clark, James M

2013-11-01

65

New fossil caddisfly from Middle Jurassic of Daohugou, Inner Mongolia, China (Trichoptera: Philopotamidae)  

Microsoft Academic Search

A new genus and new species, Juraphilopotamus lubricus gen. et sp. nov., from the Middle Jurassic Jiulongshan Formation of Daohugou, Inner Mongolia, China, is described and illustrated. It may be the first record of the family Philopotamidae in China, extending the geographic distribution of this family. A detailed description and illustration of the specimen along with a brief review of

Meixia Wang; Yunyun Zhao; Dong Ren

2009-01-01

66

New fossil mayflies (Insecta: Ephemeroptera) from the Middle Jurassic of Daohugou, Inner Mongolia, China  

Microsoft Academic Search

Jurassonurus amoenus, a new genus and species of Siphlonuridae s. l. is described from the Middle Jurassic Jiulongshan Formation of the Daohugou Village, Shantou Township, Ningcheng County, Inner Mongolia, China. The new species is estab- lished by more than 20 imago and subimago specimens in relatively good condition. Detailed description and illustration of the specimens along with a review of

Jian-Dong Huang; Dong Ren; Nina D. Sinitshenkova; Chung-Kun Shih

2008-01-01

67

New fossil Prophalangopsidae (Orthoptera, Hagloidea) from the Middle Jurassic of Inner Mongolia, China  

Microsoft Academic Search

Two new species attributed to the genus Sigmaboilus Fang, Zhang & Wang, 2007 are described from the Middle Jurassic Jiulongshan Formation of Daohugou Village, Inner Mongolia, China: Sigmaboilus fuscus sp. nov., S. peregrinus sp. nov. The diagnosis of the genus is revised.

JUNJIE GU; YUN-YUN ZHAO; DONG REN

68

Short communication New fossil caddisfly from Middle Jurassic of Daohugou, Inner Mongolia, China (Trichoptera: Philopotamidae)  

Microsoft Academic Search

A new genus and new species, Juraphilopotamus lubricus gen. et sp. nov., from the Middle Jurassic Jiulongshan Formation of Daohugou, Inner Mongolia, China, is described and illustrated. It may be the first record of the family Philopotamidae in China, extending the geographic distribution of this family. A detailed description and illustration of the specimen along with a brief review of

Meixia Wang; Yunyun Zhao; Dong Ren

69

Enigmatic Fossil Footprints from the Sundance Formation (Upper Jurassic) of Bighorn Canyon National Recreation Area, Wyoming  

Microsoft Academic Search

The Sundance Formation (Middle-Upper Jurassic) of Wyoming is well known for pterosaur footprints. Two new partial trackways from the upper Sundance Formation of the Bighorn Canyon National Recreation Area (BICA) of north-central Wyoming are enigmatic. The trackways are preserved in rippled, flaser bedded, glauconitic sand and mud. The deposits were laid down in tidal flats, behind barrier islands, along the

Jerald D. Harris; Kenneth J. Lacovara

2004-01-01

70

Two new species of Mesoplecia (Insecta: Diptera: Protopleciidae) from the late Middle Jurassic of China.  

PubMed

Two new species of Mesoplecia Rohdendorf, 1938, M. plena sp. nov. and M. fastigata sp. nov., are described from the late Middle Jurassic Jiulongshan Formation of Daohugou, Inner Mongolia, China. Based on the emended generic diagnosis of Mesoplecia by Zhang in 2007, these two new species are assigned to Mesoplecia by a combination of the following five characters: (1) Head small; (2) Vein bRs not more than twice as long as dRs; (3) M1, M2 at least 5 times as long as dM1+2; (4) bM1+2 longer than dM1+2; and (5) Legs with coxae and femora thick. In addition, a key to Mesoplecia is provided.  PMID:25081796

Lin, Xiuqin; Shih, Chungkun; Ren, Dong

2014-01-01

71

A Jurassic mammal from South America.  

PubMed

The Jurassic period is an important stage in early mammalian evolution, as it saw the first diversification of this group, leading to the stem lineages of monotremes and modern therian mammals. However, the fossil record of Jurassic mammals is extremely poor, particularly in the southern continents. Jurassic mammals from Gondwanaland are so far only known from Tanzania and Madagascar, and from trackway evidence from Argentina. Here we report a Jurassic mammal represented by a dentary, which is the first, to our knowledge, from South America. The tiny fossil from the Middle to Late Jurassic of Patagonia is a representative of the recently termed Australosphenida, a group of mammals from Gondwanaland that evolved tribosphenic molars convergently to the Northern Hemisphere Tribosphenida, and probably gave rise to the monotremes. Together with other mammalian evidence from the Southern Hemisphere, the discovery of this new mammal indicates that the Australosphenida had diversified and were widespread in Gondwanaland well before the end of the Jurassic, and that mammalian faunas from the Southern Hemisphere already showed a marked distinction from their northern counterparts by the Middle to Late Jurassic. PMID:11894091

Rauhut, Oliver W M; Martin, Thomas; Ortiz-Jaureguizar, Edgardo; Puerta, Pablo

2002-03-14

72

Late Jurassic to Eocene geochemical evolution of volcanic rocks in Puerto Rico  

SciTech Connect

The Late Jurassic to Eocene deformed volcanic, volcaniclastic and sedimentary rocks of Puerto Rico are divided into three igneous provinces, the southwestern, central, and northeastern igneous province. Based on the stratigraphic position approximate ages could be assigned to the flow rocks in these provinces. Ba/Nb and La/Sm diagrams are presented to illustrate the origin and evolution of the flow rocks. The oldest rock in the southwestern province may include MORB. Early Cretaceous volcanic rocks in the central and northeastern province have low Ba/nb and La/Sm, that are interpreted as an early island arc stage, with none or only minor contribution of slab-derived material. The Late Cretaceous to Eocene volcanic rocks have a wide range of values for the Ba/Nb and La/Sm that are interpreted as the result of admixture of a variable amount of slab-derived material. The Maricao Basalt (Maastrichtian to Eocene) in the southeastern igneous province has the geochemical signature of magmas formed in an extensional setting.

Schellekens, J.H. (Univ. of Puerto Rico, Mayaguez (Puerto Rico))

1991-03-01

73

An Investigation of mid to late Holocene fossil insects from raised bogs  

E-print Network

1 An Investigation of mid to late Holocene fossil insects from raised bogs in the Irish Midlands the results of late Holocene insect fossil analysis from six raised bogs in the Irish Midlands. A distribution patterns in the taphonomy of the insect fossil assemblages, through the development of the bog and across

Sheldon, Nathan D.

74

[The Journal of Geology, 2004, volume 112, p. 643653] 2004 by The University of Chicago. All rights reserved. 0022-1376/2004/11206-0003$15.00 Late Jurassic Climates, Vegetation, and Dinosaur Distributions  

E-print Network

rights reserved. 0022-1376/2004/11206-0003$15.00 643 Late Jurassic Climates, Vegetation, and Dinosaur T The Jurassic and Cretaceous are considered to have been warmer than today on the basis of various climate data, and dinosaurs to infer broadscale geographic patterns for the Late Jurassic. These provide a context for our

Rees, Allister

75

Detrital zircon U-Pb ages of Late Triassic-Late Jurassic deposits in the western and northern Sichuan Basin margin: constraints on the foreland basin provenance and tectonic implications  

NASA Astrophysics Data System (ADS)

Upper Triassic to Upper Jurassic strata in the western and northern Sichuan Basin were deposited in a synorogenic foreland basin. Ion-microprobe U-Pb analysis of 364 detrital zircon grains from five Late Triassic to Late Jurassic sandstone samples in the northern Sichuan Basin and several published Middle Triassic to Middle Jurassic samples in the eastern Songpan-Ganzi Complex and western and inner Sichuan Basin provide an initial framework for understanding the Late Triassic to Late Jurassic provenance of western and northern Sichuan Basin. For further understanding, the paleogeographic setting of these areas and neighboring hinterlands was constructed. Combined with analysis of depocenter migration, thermochronology and detrital zircon provenance, the western and northern Sichuan Basin is displayed as a transferred foreland basin from Late Triassic to Late Jurassic. The Upper Triassic Xujiahe depocenter was located at the front of the Longmen Shan belt, and sediments in the western Sichuan Basin shared the same provenances with the Middle-Upper Triassic in the Songpan-Ganzi Complex, whereas the South Qinling fed the northern Sichuan Basin. The synorogenic depocenter transferred to the front of Micang Shan during the early Middle Jurassic and at the front of the Daba Shan during the middle-late Middle Jurassic. Zircons of the Middle Jurassic were sourced from the North Qinling, South Qinling and northern Yangtze Craton. The depocenter returned to the front of the Micang Shan again during the Late Jurassic, and the South Qinling and northern Yangtze Craton was the main provenance. The detrital zircon U-Pb ages imply that the South and North China collision was probably not finished at the Late Jurassic.

Luo, Liang; Qi, Jia-Fu; Zhang, Ming-Zheng; Wang, Kai; Han, Yu-Zhen

2014-09-01

76

A REVIEW OF THE VERTEBRATE FAUNA OF THE LOWER JURASSIC NAVAJO SANDSTONE IN ARIZONA  

Microsoft Academic Search

The Lower Jurassic Navajo Sandstone of northern Arizona and southern Utah has yielded a diverse assemblage of late Early Jurassic terrestrial tetrapods from eolian and associated paleoenvironments. Although rare, vertebrate body fossils are represented by specimens of tritylodonts, crocodylomorphs, sauropodomorphs, and basal theropods (including Segisaurus halli). The vertebrate ichnofossil record is diverse and includes synapsids (Brasilichnium), crocodylomorphs (cf. Batrachopus), ornithischians

RANDALL B. IRMIS

2005-01-01

77

Trace fossils from Jurassic lacustrine turbidites of the Anyao Formation (central China) and their environmental and evolutionary significance  

USGS Publications Warehouse

The Lower Jurassic Anyao Formation crops out near Jiyuan city, western Henan Province, central China. It is part of the infill of the nonmarine early Mesozoic Jiyuan-Yima Basin. In the Jiyuan section, this unit is about 100 m thick and consists of laterally persistent, thin and thick-bedded turbidite sandstones and mudstones displaying complete and base- or top-absent Bouma sequences, and thickbedded massive sandstones. The Anyao Formation records sedimentation within a lacustrine turbidite system developed in a pull-apart basin. Processes involved include high and low density turbidity currents, sometimes affected by liquefaction or fluidization. Facies analysis suggests that this succession is formed by stacked aggradational turbidite lobes. The absence of thick mudstone packages indicates that background sedimentation was subordinate to high frequency turbidite deposition. The Anyao Formation hosts a moderately diverse ichnofauna preserved as hypichnial casts on the soles of thin-bedded turbidite sandstones. The ichnofauna consists of Cochlichnus anguineus, Helminthoidichnites tenuis, Helminthopsis abeli, H. hieroglyphica, Monomorphichnus lineatus, Paracanthorhaphe togwunia, Tuberculichnus vagans, Vagorichnus anyao, tiny grazing trails, and irregularly branching burrows. Vagorichnus anyao occurs not only as a discrete trace, but also as a compound ichnotaxon intergrading with Gordia marina and Tuberculichnus vagans. Both predepositional and post-depositional traces are present on the soles of turbidites. This ichnofauna comprises both feeding and grazing traces produced by a deposit-feeding lacustrine benthic biota. Crawling traces are rare. Although certain ichnofossils (e.g. V. anyao, P. togwunia) show overall similarities with deep-sea agrichnia, they differ in reflecting remarkably less specialized feeding strategies, displaying overcrossing between specimens (and to a lesser extent, self-crossing), and in the case of V. anyao recording post-turbidite burrowing activity. The development of less specialized strategies than those displayed by deep-marine ichnofaunas may be related to less stable conditions, typical of lake settings. Oxygenation, energy, sedimentation rate (both event and background), food supply, soft-sediment deformation and erosion rate have mainly influenced trace-fossil distribution. Turbidity currents would have ensured oxygen (as well as food) supply to deep lake settings, thus allowing the establishment of a moderately diverse biota. Biogenic structures were mostly confined to the outer, low energy areas. High sedimentation rates and strong erosion precluded preservation of ichnofossils in inner lobe settings. The Anyao ichnofauna is of significance in furthering knowledge of the colonization of deep lakes throughout the stratigraphic record and in identification of additional nonmarine ichnofacies. The analyzed ichnofauna resembles late Paleozoic lacustrine assemblages described from different localities around the world and is regarded as a Mesozoic example of the Mermia ichnofacies. However, when compared with Paleozoic assemblages, the Anyao ichnofauna shows a clear dominance of burrows over surface trails, deeper burrowing penetration, larger size, and presence of relatively more complex structures. The high burrow/surface trail ratio may be indicative of lower preservation potential in the latter, thus reflecting a tap-honomic overprint. In contrast to the Paleozoic examples, the establishment of a relatively well-developed lacustrine infauna may have precluded preservation of surface trails. Burrower activity probably obliterated biogenic structures formed close to the sediment-water interface. ?? 1996 OPA (Overseas Publishers Association) Amsterdam B.V. Published in The Netherlands by Harwood Academic Publishers GmbH.

Buatois, L.A.; Mangano, M.G.; Wu, X.; Zhang, G.

1996-01-01

78

Magnetic fabric of Late Jurassic arc plutons and kinematics of terrane accretion in the Blue Mountains, northeastern Oregon  

Microsoft Academic Search

The Blue Mountains Province of northeastern Oregon, western Idaho, and southeastern Washington (USA) consists of the amalgamated Wallowa distal island arc, Baker mélange-bearing accretionary wedge–forearc, and Olds Ferry fringing island arc terranes. Anisotropy of magnetic susceptibility (AMS) and particularly the orientation of magnetic lineations in Middle to Late Jurassic diorite–tonalite–granodiorite plutons intruding the Baker terrane indicate a change in tectonic

Ji?í Žák; Kryštof Verner; Kenneth Johnson; Joshua J. Schwartz

79

Revision of the Late Jurassic crocodyliform Alligatorellus, and evidence for allopatric speciation driving high diversity in western European atoposaurids  

PubMed Central

Atoposaurid crocodyliforms represent an important faunal component of Late Jurassic to Early Cretaceous Laurasian semi-aquatic to terrestrial ecosystems, with numerous spatiotemporally contemporaneous atoposaurids known from western Europe. In particular, the Late Jurassic of France and Germany records evidence for high diversity and possible sympatric atoposaurid species belonging to Alligatorellus, Alligatorium and Atoposaurus. However, atoposaurid taxonomy has received little attention, and many species are in need of revision. As such, this potentially high European diversity within a narrow spatiotemporal range might be a taxonomic artefact. Here we provide a taxonomic and anatomical revision of the Late Jurassic atoposaurid Alligatorellus. Initially described as A. beaumonti from the Kimmeridgian of Cerin, eastern France, additional material from the Tithonian of Solnhofen, south-eastern Germany, was subsequently referred to this species, with the two occurrences differentiated as A. beaumonti beaumonti and A. beaumonti bavaricus, respectively. We provide a revised diagnosis for the genus Alligatorellus, and note a number of anatomical differences between the French and German specimens, including osteoderm morphology and the configuration and pattern of sculpting of cranial elements. Consequently, we restrict the name Alligatorellus beaumonti to include only the French remains, and raise the rank of the German material to a distinct species: Alligatorellus bavaricus. A new diagnosis is provided for both species, and we suggest that a recently referred specimen from a coeval German locality cannot be conclusively referred to Alligatorellus. Although it has previously been suggested that Alligatorellus, Alligatorium and Atoposaurus might represent a single growth series of one species, we find no conclusive evidence to support this proposal, and provide a number of morphological differences to distinguish these three taxa that appear to be independent of ontogeny. Consequently, we interpret high atoposaurid diversity in the Late Jurassic island archipelago of western Europe as a genuine biological signal, with closely related species of Alligatorellus, Alligatorium and Atoposaurus in both French and German basins providing evidence for allopatric speciation, potentially driven by fluctuating highstand sea levels. PMID:25279270

Mannion, Philip D.

2014-01-01

80

Late Paleozoic to Jurassic tectonic evolution of the Bogda area (northwest China): Evidence from detrital zircon U-Pb geochronology  

NASA Astrophysics Data System (ADS)

Since the Cenozoic, the Tian Shan is rejuvenated by crustal shortening related to the ongoing India-Asia collision. However, the tectonic process prior to the Cenozoic remains ambiguous, especially in the Bogda area of the eastern Tian Shan. The continuous Late Paleozoic-Mesozoic sequences in the Bogda area record abundant information about the basin-mountain interaction. U-Pb (LA-ICP-MS) dating of detrital zircons from seven sandstone samples from Permian to Jurassic was used to investigate the changes of provenance and basin-mountain interaction in the Bogda area. During the Permian, proximal and synchronous pyroclastic materials were the major source. The Late Paleozoic magmatic belt in the North Tian Shan (NTS) had gradually become one of the main sources by the Late Permian, which implies the uplift and exhumation in the NTS area. This is interpreted in terms of near-source sedimentation in basin developing in a post-orogenic extension setting. The large range of U-Pb ages of detrital zircons observed in the Early-Middle Jurassic sediments encompasses most of the available sources implying a wide drainage pattern developing on a rather flat topography. Re-emergence of the Early Permian peak in the spectrum implies that the Bogda Mountains has existed as a gentle positive relief and began to provide materials to the submountain regions. The southern Junggar Basin extended towards to the south and evolved as a passively subsiding basin from the Middle Triassic to the Middle Jurassic. However, the synchronous pyroclastic (tuff) and the exhumed late Paleozoic detrital materials from the uplifted Bogda Mountains were the major component of the Upper Jurassic sediments. Associated to the conglomerate in the Kalaza Formation, the basin-range evolution entered a compression uplift stage. The basin pattern evolution of the Bogda area is consistent with that of the southern Junggar Basin.

Tang, Wenhao; Zhang, Zhicheng; Li, Jianfeng; Li, Ke; Chen, Yan; Guo, Zhaojie

2014-06-01

81

Revision of the Late Jurassic crocodyliform Alligatorellus, and evidence for allopatric speciation driving high diversity in western European atoposaurids.  

PubMed

Atoposaurid crocodyliforms represent an important faunal component of Late Jurassic to Early Cretaceous Laurasian semi-aquatic to terrestrial ecosystems, with numerous spatiotemporally contemporaneous atoposaurids known from western Europe. In particular, the Late Jurassic of France and Germany records evidence for high diversity and possible sympatric atoposaurid species belonging to Alligatorellus, Alligatorium and Atoposaurus. However, atoposaurid taxonomy has received little attention, and many species are in need of revision. As such, this potentially high European diversity within a narrow spatiotemporal range might be a taxonomic artefact. Here we provide a taxonomic and anatomical revision of the Late Jurassic atoposaurid Alligatorellus. Initially described as A. beaumonti from the Kimmeridgian of Cerin, eastern France, additional material from the Tithonian of Solnhofen, south-eastern Germany, was subsequently referred to this species, with the two occurrences differentiated as A. beaumonti beaumonti and A. beaumonti bavaricus, respectively. We provide a revised diagnosis for the genus Alligatorellus, and note a number of anatomical differences between the French and German specimens, including osteoderm morphology and the configuration and pattern of sculpting of cranial elements. Consequently, we restrict the name Alligatorellus beaumonti to include only the French remains, and raise the rank of the German material to a distinct species: Alligatorellus bavaricus. A new diagnosis is provided for both species, and we suggest that a recently referred specimen from a coeval German locality cannot be conclusively referred to Alligatorellus. Although it has previously been suggested that Alligatorellus, Alligatorium and Atoposaurus might represent a single growth series of one species, we find no conclusive evidence to support this proposal, and provide a number of morphological differences to distinguish these three taxa that appear to be independent of ontogeny. Consequently, we interpret high atoposaurid diversity in the Late Jurassic island archipelago of western Europe as a genuine biological signal, with closely related species of Alligatorellus, Alligatorium and Atoposaurus in both French and German basins providing evidence for allopatric speciation, potentially driven by fluctuating highstand sea levels. PMID:25279270

Tennant, Jonathan P; Mannion, Philip D

2014-01-01

82

Late Jurassic ductile shearing and tectonic breccias in the eastern Great Basin of Nevada and Utah  

SciTech Connect

The Paleozoic sedimentary prism was dismembered in the Late Jurassic by shearing initiated at stratigraphic positions in the following list: (1) base of Meade Peak Shale, (2) base of Summit Springs Evaporites, (3) top of contact Chert Member of the Rib Hill Formation, (4) base of Unit G of the Ely Formation, (5) base of the Ely Limestone, (6) base of the Diamond Peak Sandstone, (7) base of Chainman Shale, (8) base of the Joana Limestone, (9) base of the Pilot Formation, (10) base of Lower Guilmette Limestone, (11) in siltstone at the top of Ely Springs (Hanson Creek) Formation, (12) top and base of the Eureka Quartzite, (13) base of the Dunderberg Shale, and (14) base of Pioche Shale and top of Prospect Mountain Quartzite. The largest are regional decollectments, e.g., Summit Springs, Chainman, Blue Eagle, Silver Island, and Snake Range. The lesser shears vary in position and extent with lithofacies distribution. Shales at all levels behaved ductilely. Carbonates locally behaved ductilely up to the base of the Pilot Formation, but more commonly below the Dunderberg Shale. Brittle deformation in the carbonates produced megatectonic breccias below the shears. These regional breccias became reservoirs for the pore fluids and clay-held fluids expelled from primary source rocks and reservoirs by the dynamic pressures. Igneous plutons injected from 150-30 Ma crosscut and dilated the shear zones, creating hydrothermal systems within the tectonic reservoirs.

Welsh, J.E. Sr. (Natural Resources Geologist, Holladay, UT (United States))

1993-08-01

83

New fossil Praeaulacinae wasps (Insect: Hymenoptera: Evanioidea: Praeaulacidae) from the Middle Jurassic of China.  

PubMed

A new genus with a new species, Archaulacus probus gen. et sp. nov., and two new species, Praeaulacus subrhombeus sp. nov., P. tenellus sp. nov., belonging to the subfamily Praeaulacinae (Praeaulacidae) are described and illustrated. The specimens were collected from the Middle Jurassic of Jiulongshan Formation at Daohugou in Inner Mongolia, China. Archaulacus gen. nov. differs from other genera of Praeaulacinae in having the first abscissa of Rs of the fore wing subvertical to R and 2m-cu slightly basad of 2r-m. This is the first time that these characters are reported for the Praeaulacinae. Based on new information provided by the new species, an updated key to the known species of Praeaulacus is provided. PMID:24943440

Li, Longfeng; Shih, Chungkun; Ren, Dong

2014-01-01

84

Molecular fossils and the late rise of oxygenic photosynthesis  

NASA Astrophysics Data System (ADS)

Biomarkers are the molecular fossils of natural products such as lipids and pigments. They can yield a wealth of information about early microbial ecosystems and are particularly valuable when preserved in > 1 billion-year old (Ga) sedimentary rocks where conventional fossils are often lacking. Therefore, in 1999, the detection of traces of biomarkers in 2.5 to 2.7 Ga shales from Western Australia (Brocks et al. 1999, Summons et al. 1999) was celebrated as a breakthrough. The discovery, which was later confirmed by several independent studies, led to far reaching conclusions about the early evolution of oxygenic photosynthesis (Summons et al. 1999) and ancestral eukaryotes (Brocks et al. 1999). However, here we present new data based on the carbon isotopic composition of solidified hydrocarbons (Rasmussen et al. 2008) and the spatial distribution of liquid hydrocarbons within the original 2.5 and 2.7 Ga shales (Brocks 2011) that demonstrate that the molecules must have entered the rocks much later in Earth's history and therefore provide no information about the Archean (>2.5 Ga) biosphere or environment. The elimination of the Archean biomarker data has immense implications for our understanding of Earth's early biosphere. 2-Methylhopanes have been interpreted as evidence for the existence of cyanobacteria at 2.7 Ga, about ~300 million years before the atmosphere became mildly oxygenated in the Great Oxidation Event (GOE; between 2.45 and 2.32 Ga). Now, the oldest direct fossil evidence for cyanobacteria reverts back to 2.15 Ga, and the most ancient robust sign for oxygenic photosynthesis becomes the GOE itself. Moreover, the presence of steranes has been interpreted as evidence for the existence of ancestral eukaryotes at 2.7 Ga. However, without the steranes, the oldest fossil evidence for the domain falls into the range ~1.78-1.68 Ga. Recognition that the biomarkers from Archean rocks are not of Archean age renders permissive hypotheses about a late evolution of oxygenic photosynthesis, and an anoxygenic phototrophic origin of the vast deposits of Archean banded iron formation. Brocks et al. (1999) Science 285, 1033-1036. Brocks (2011) Geochim. Cosmochim. Acta, 75, 3196-3213. Rasmussen et al. (2008) Nature 455, 1101-1104. Summons et al. (1999) Nature 400, 554-557.

Brocks, J. J.

2012-04-01

85

Paleomagnetism of the Front Range (Colorado) Morrison Formation and an alternative model of Late Jurassic North American apparent polar wander  

SciTech Connect

A paleomagnetic study of the Upper Jurassic Morrison Formation in the Front Range of central Colorado yields high-unblocking-temperature, dual-polarity magnetizations. With respect to known paleohorizontal, the inclinations (absolute mean = 57.3{degree}, 95% confidence interval = 52.3{degree} to 63.1{degree}, N = 8 sites) pass tilt and reversal tests, whereas the dispersion in declinations can be attributed to apparent or real tectonic rotations and sedimentary processes. The site-centered colatitudinal locus of possible Front Range Morrison poles partially overlaps the 'upper' pole, but it excludes the 'lower' pole from the Morrison Formation on the Colorado Plateau as well as the 151 Ma Glance conglomerate pole from the Basin and Range province of southeastern Arizona. The authors offer various explanations for these disparities and suggest an alternative model of Late Jurassic North American apparent polar wander through {approximately}70{degree}N which is supported by Late Jurassic European poles (with positive stability tests) transferred to North American coordinates.

Fossen, M.C. Van; Kent, D.V. (Columbia Univ., Palisades, NY (United States))

1992-03-01

86

Tectonic and magmatic evolution of a fossil (Ultra-)Slow Spreading Ocean: the study case of the Jurassic Ligurian Tethys.  

NASA Astrophysics Data System (ADS)

The Jurassic Ligurian Tethys oceanic basin has been recognized as the fossil analogue of modern (Ultra- )Slow Spreading Ridges. Stratigraphic and structural studies on the Western Alpine - Northern Apennine (AA) ophiolites, that are remnants of the lithosphere of the ancient basin, evidence that the basin was characterized by the sea-floor exposure on mantle peridotites, discontinuously covered by MORB volcanites and pelagic sediments (i.e. radiolarion cherts). The related passive margins were typically not-volcanic. Palaeogeographic restorations indicate that exhumed sub-continental mantle was exposed at the ocean- continent transition (OCT) zones, frequently associated to continental crust material and pelagic sediments. These exhumed sub-continental lithospheric peridotites were equilibrated under spinel-facies conditions, preserving diffuse structural relicts of precursor garnet, and show widespread spinel(-garnet)-pyroxenites bands. Sm-Nd isotope data on Cpx from these peridotites indicate DMM affinity and Proterozoic model ages, that have been interpreted as early accretion to, and long residence in, the sub-continental lithosphere. OCT peridotites frequently show strong localized deformation along km-scale shear zones that were formed during lithosphere extension leading to the oceanic opening. Isotope data indicate that mantle exhumation during lithosphere extension was already active during Triassic times and was most probably accomodated by a network of lithosphere-scale shear zones. Lithospheric thinning caused asthenosphere adiabatic upwelling and decompression melting along the axial zone of the extensional system. The asthenospheric MORB melts infiltrated by porous flow and percolated through the overlying extending lithospheric mantle causing significant melt-peridotite interaction. The pristine lithospheric mantle was tranformed to strongly pyroxene-depleted (i.e. reactive and replacive peridotites) or plagioclase-enriched (i.e. impregnated and refertilized peridotites) rock types. Isotope data indicate that asthenosphere melting and lithosphere melt percolation started during Early Jurassic times and the pristine lithospheric peridotites were isotopically equilibrated with the percolating melts, attaining MORB isotopic signatures. Melt impregnation (i.e. interstitial crystallization) caused significant melt entrapment in the extending lithosphere: accordingly, the rift evolution of the continental system, from rifting to drifting to formation of the passive margins was significantly not-volcanic (but not a-magmatic). Ongoing extension caused complete failure of the continental crust and peridotites from the sub-continental mantle were exposed to the sea-floor. Sub-continental peridotites were exhumed and exposed at the sea- floor close to the continental margins, whereas the strongly modified peridotites formed by melt-rock interaction were exhumed and exposed at more internal oceanic settings of the basin. Present knowledge indicates that none of the known AA ophiolitic peridotites from the Jurassic Ligurian Tethys can be recognized as simple refractory residua after Jurassic asthenosphere partial melting. This could indicate that the Ligurian Tethys never reached a complete oceanic stage, where magmatic rocks and mantle refractory residua should be almost coeval and cogenetic.

Piccardo, G. B.

2008-12-01

87

Tripartichnus n. igen. — a new trace fossil from the Buntsandstein (Lower Triassic) and from the Solnhofen Lithographic Limestones (Upper Jurassic), Germany  

Microsoft Academic Search

Two species of a new trace fossil genus (cubichnia) are described:Tripartichnus triassicus n. igen., n. isp. from the “Plattensandstein“ (Upper Buntsandstein, Röt-Folge, Lower Triassic) of Keltern-Dietlingen (Enzkreis,\\u000a Baden-Württemberg, SW-Germany) andTripartichnus imbergi n. igen., n. isp. from the Solnhofen Lithographic Limestones (Upper Jurassic, Tithonian) from Waiting and Pfalzpaint (district\\u000a of Eichstätt, Bavaria, SE Germany). Due to the characteristic shape of the

Lothar H. Vallon; Martin Röper

2006-01-01

88

Carbon-isotope record of the Early Jurassic (Toarcian) Oceanic Anoxic Event from fossil wood and marine carbonate (Lusitanian Basin, Portugal)  

Microsoft Academic Search

The Toarcian Oceanic Anoxic Event (OAE) in the Early Jurassic (?183 Ma ago) was characterized by widespread near-synchronous deposition of organic-rich shales in marine settings, as well as perturbations to several isotopic systems. Characteristically, two positive carbon-isotope excursions in a range of materials are separated by an abrupt negative shift. Carbon-isotope profiles from Toarcian fossil wood collected in England and Denmark

Stephen P. Hesselbo; Hugh C. Jenkyns; Luis V. Duarte; Luiz C. V. Oliveira

2007-01-01

89

Carbon-isotope record of the Early Jurassic (Toarcian) Oceanic Anoxic Event from fossil wood and marine carbonate (Lusitanian Basin, Portugal)  

Microsoft Academic Search

The Toarcian Oceanic Anoxic Event (OAE) in the Early Jurassic (˜ 183 Ma ago) was characterized by widespread near-synchronous deposition of organic-rich shales in marine settings, as well as perturbations to several isotopic systems. Characteristically, two positive carbon-isotope excursions in a range of materials are separated by an abrupt negative shift. Carbon-isotope profiles from Toarcian fossil wood collected in England

Stephen P. Hesselbo; Hugh C. Jenkyns; Luis V. Duarte; Luiz C. V. Oliveira

2007-01-01

90

Chemostratigraphic Constraints on Late Jurassic Paleoceanography of the East Texas Basin, Southern Margin of North America  

NASA Astrophysics Data System (ADS)

Late Jurassic deposition of organic-rich muds occurred in the East Texas Basin of modern-day Texas and Louisiana in a ramp-style marine setting during the early formation of the Gulf of Mexico. These mudrocks are regional known as the Haynesville and Bossier Formations. The goals of the current project are to 1) develop a better understanding of the paleoceanographic conditions and the depositional environment, and 2) develop linkages between the record from the southern margin of North America and other well-documented paleoceanographic records of Kimmeridgian age. Ten drill cores from the study area have been studied for their geochemistry. Each core was scanned at a 1-foot interval using a handheld x-ray fluorescence instrument, providing rapid, quantitative analysis of the following elemental concentrations: Mg, Al, S, Si, P, K, Ti, Ca, Mn, Fe, Mo, Cr, Ni, Cu, Zn, Th, Rb, U, Sr, Zr, and V. In addition, preliminary interpretations for total inorganic carbon (TIC), total organic carbon (TOC), total nitrogen (%N), and bulk rock TOC and N isotopic composition of core samples reveal distinct differences between the Bossier and Haynesville formations. Results from previous geochemical studies suggest that the siliciclastic-dominated Bossier formation has less TOC than the underlying Haynesville formation. Furthermore, the Haynesville is much more carbonate-rich (calcite) than the overlying Bossier. An upwardly increasing trend in Si/Al in some cores suggests increasing detrital quartz influx. A linear relationship between Fe and Al suggest that iron is primarily in clay mineral phases in the Haynesville. Enrichments in Mo concentrations and Cr/V ratios reveal periods of anoxic conditions.

Mainali, P.; Rowe, H. D.

2010-12-01

91

A new genus and two new species of fossil Elaterids from the Yixian Formation of Western Liaoning, China (Coleoptera: Elateridae)  

Microsoft Academic Search

A new genus and two new species of fossil Elateridae are described and illustrated: Paralithomerus gen. nov., P. exquisi- tus sp. nov, and P. parallelus sp. nov. Both species were collected from the Late Jurassic-Early Cretaceous Yixian For- mation of western Liaoning, China. Fossil elaterids expressing a sutured mesoventrite have been otherwise discovered only from the Upper Jurassic strata of

HUALI CHANG; FAN ZHANG; DONG REN

92

Strontium and carbon isotope stratigraphy of the Late Jurassic shallow marine limestone in western Palaeo-Pacific, northwest Borneo  

NASA Astrophysics Data System (ADS)

Strontium and carbon isotope stratigraphy was applied to a 202 m-thick shallow marine carbonate section within the Late Jurassic Bau Limestone at the SSF quarry in northwest Borneo, Malaysia, which was deposited in the western Palaeo-Pacific. Strontium isotopic ratios of rudist specimens suggest that the SSF section was formed between the latest Oxfordian (155.95 Ma) and the Late Kimmeridgian (152.70 Ma), which is consistent with previous biostratigraphy. The ?13Ccarb values of bulk carbonate range from -0.10 to +2.28‰ and generally show an increasing upward trend in the lower part of the section and a decreasing upward trend in the upper part of the section. A comparable pattern is preserved in the ?13Corg isotope record. Limestone samples of the SSF section mainly preserve the initial ?13Ccarb values, except for the interval 84-92 m, where an apparent negative anomaly likely developed as a result of meteoric diagenesis. Comparing with the Tethyan ?13Ccarb profile, a negative anomaly in the lower SSF section can be correlated with the lowered ?13C values around the Oxfordian/Kimmeridgian boundary. In addition, ?13Ccarb values of the Bau Limestone are generally ?1‰ lower than the Tethyan values, but comparable with the values reported from Scotland and Russia, located in Boreal realm during the Late Jurassic. This suggests that either the Tethyan record or the other records have been affected by the ?13C values of regionally variable dissolved inorganic carbon (DIC). The Late Jurassic ?13CDIC values are thought to have been regionally variable as a result of their palaeoceanographic settings. This study shows that ?13C chemostratigraphy of the Palaeo-Pacific region contributes to an improved understanding of global carbon cycling and oceanography during this time period.

Kakizaki, Yoshihiro; Weissert, Helmut; Hasegawa, Takashi; Ishikawa, Tsuyoshi; Matsuoka, Jun; Kano, Akihiro

2013-09-01

93

and Early Jurassic sediments, and  

E-print Network

and Early Jurassic sediments, and patterns of the Triassic-Jurassic PAUL E. OLSEN AND tetrapod transition HANS-DIETER SUES Introduction The Late Triassic-Early Jurassic boundary is fre- quently cited to other terrestrial and extraterrestrial phenomena (see Chapter 24). The Triassic-Jurassic boundary takes

Olsen, Paul E.

94

The generation of high Sr/Y plutons following Late Jurassic arc-arc collision, Blue Mountains province, NE Oregon  

NASA Astrophysics Data System (ADS)

High Sr/Y plutons (Sr/Y > 40) occupy large areas in ancient and modern orogenic belts, yet considerable controversy exists regarding mechanisms of their generation, the tectonic settings in which they form, and their relationship to contractional deformation through time. In the Blue Mountains province (NE Oregon), a suite of Late Jurassic (148-145 Ma), high Sr/Y plutons intrude Middle Jurassic (162-157 Ma), low Sr/Y (< 40) arc-related lavas and plutons in the Dixie Butte area immediately after widespread Late Jurassic arc-arc collision (159-154 Ma). Early, pre- to syn-kinematic low Sr/Y lavas and plutons (162-157 Ma) have flat to slightly enriched light rare earth element (REE) abundances, low Sr (< 400 ppm) and Sr/Y values (< 40), and strongly positive initial epsilon Hf values (+ 10.1 to + 12.3: 2? weighted average). Ce/Y values from basalts and gabbros yield a maximum crustal thickness of ~ 23 km. These geochemical and isotopic features suggest derivation from a depleted-mantle source and/or shallow-level (? 40 km) melting of pre-existing island arc crust with little to no evolved crustal input. In contrast, post-kinematic high Sr/Y plutons (148-145 Ma) are more compositionally restricted (tonalite-trondhjemite-granodiorite) and display depleted heavy REE abundances, an absence of Eu anomalies, elevated Sr (> 600 ppm) and Sr/Y values (> 40), and positive initial epsilon Hf values (+ 10.5 to + 7.8: 2? weighted average). These geochemical and isotopic results are consistent with geochemical models suggesting derivation from partial melting of island arc crust in the presence of a plagioclase-poor to absent, clinopyroxene + hornblende + garnet-bearing source (depths > 35-40 km). We propose that the transition from low Sr/Y to high Sr/Y magmatism resulted from orogenic thickening of island arc crust in the Dixie Butte area during Late Jurassic arc-arc collision between the Olds Ferry and Wallowa island arcs at 159-154 Ma. This fundamental change in crustal structure influenced post-orogenic magmatism and resulted in a relatively brief (~ 3 myr: 148-145 Ma) episode of high Sr/Y magmatism. Other high Sr/Y plutons occur throughout the US sector of the western North American Cordillera (e.g., Salmon River suture zone, Klamath Mountains, Peninsular Ranges) and closely follow major contractional events involving arc-arc and arc-continent collisions.

Schwartz, Joshua J.; Johnson, Kenneth; Miranda, Elena A.; Wooden, Joseph L.

2011-09-01

95

Recognition and analysis of fossil soils developed on alluvium: a Late Ordovician example  

Microsoft Academic Search

A series of fossil soils in alluvial red beds from the upper Juniata Formation, near Potters Mills, Pennsylvania, provide evidence of soil forming processes during the late Ordovician. Paleogeographic and facies considerations indicate that the fossil soils formed floodplains west of the Taconic uplift. Most studies of paleosols of this age or older have considered soils developed on metamorphic or

C. R. Feakes; G.J. Retallack

1985-01-01

96

Geology, petrology and tectonic setting of the Late Jurassic ophiolite in Hokkaido, Japan  

Microsoft Academic Search

The Gokurakudaira Formation, which has a N–S zonal distribution within a latest Jurassic greenstone belt in Hokkaido Island, Japan, constitutes the uppermost ultramafic–mafic unit of the Horokanai Ophiolite. The following three hypotheses for the origin of the ophiolite have been proposed: (1) a mid-oceanic ridge; (2) an oceanic plateau; and (3) an island arc. The Gokurakudaira Formation can be subdivided

Reishi Takashima; Hiroshi Nishi; Takeyoshi Yoshida

2002-01-01

97

Microbial crusts of the late jurassic: Composition, palaeoecological significance and importance in reef construction  

Microsoft Academic Search

Summary  Upper Jurassic reefs contain variable amounts of calcareous microbial crusts. In examples from Portugal, Spain and southern\\u000a Germany they occur within coral biostromes and bioherms, mixed coral-siliceous sponge reefs, siliceous sponge meadows and\\u000a mudmounds, and build up thrombolities with or without additional reef metazoans. The crusts are of paramount importance for\\u000a the establishment and development of positive buildups. Commonly, reef

Reinhold R. Leinfelder; Martin Nose; Dieter U. Schmid; Winfried Werner

1993-01-01

98

Fossil organic carbon fluxes released by chemical and mechanical weathering. Jurassic marls of Draix experimental watersheds, France.  

NASA Astrophysics Data System (ADS)

Fate of Fossil Organic Carbon (FOC), originating from sedimentary rock weathering, is a major unknown into carbon cycle. Generally considered as degradable and as a CO2 source for the atmosphere, its occurrence was highlighted by numerous studies in various pools, such as rivers, soils and recent sediments, indicating a potential resistance to weathering. This work focuses on annual FOC fluxes released by chemical and mechanical weathering of Jurassic marls occurring in the Draix experimental watersheds (Alpes de Haute Provence, France). Results of optical, geochemical, molecular and isotopical analyses allow to confirm the FOC occurrence and to its contribution, both in the studied soils and riverine particles. In detail, no FOC losses are observed for rock mechanical weathering process, and FOC losses do not exceed 30 % for rocks chemical weathering process. Annual export monitoring of solid and dissolved materials, obtained for twenty years at the watershed outlets, allowed FOC fluxes to be modelled. These fluxes mainly depend on watershed geomorphologic characteristics, such as vegetation rate, slope and annual precipitation heights. Results show that FOC fluxes released by rock mechanical erosion (FmFOC) and exported in rivers loads, range between 0.1 and 100 t km2 year-1, whereas those released by rocks chemical weathering (FcFOC) range between 1 and 7 t km2 year-1. Developed models permit to estimate the temporal evolutions of FOC fluxes: since the XIX th century, in order to limit mechanical weathering in this area, human reforestation brings an increase of chemical weathering, to the detriment of mechanical one. In the studied watersheds, since 1850, FcFOC average flux increased from 0.15 to 5 t km2 year-1 whereas FmFOC average flux dropped of 70 to 0.1 t km2 year-1. Models also permit to test FOC contribution from small watersheds to regional scale. In natural conditions, such geological formations can deliver 31050 t year-1 FOC to the Rhône river. Such FOC contribution can reach 15 % of the river's Particulate Organic Carbon flux. These results emphasize the importance of FOC delivery in modern carbon fluxes and in carbon cycle.

Graz, Y.; di-Giovanni, C.; Copard, Y.; Boussafir, M.; Laggoun-Défarge, F.; Mathys, N.; Rey, F.; Sizaret, S.

2009-04-01

99

Lithological and paleontological content of the Carboniferous-Jurassic Canterbury Suite, South Island, New Zealand  

Microsoft Academic Search

The late Paleozoic and Mesozoic quartzo-feldspathic Canterbury Suite contains a wide range of detrital lithotypes and facies, representing many depositional environments. The stratification, sedimentary structures, and fossils characteristic of 11 lithotypes are described and interpreted in terms of probable depositional environments.Fifteen recognisable faunal zones represent only part of the total time span of the Canterbury Suite (Carboniferous to late Jurassic).

P. B. Andrews; I. G. Speden; J. D. Bradshaw

1976-01-01

100

Age, geochemistry, paleotectonic setting and metallogeny of Late Triassic-Early Jurassic intrusions in the Yukon and eastern Alaska: A preliminary report  

Microsoft Academic Search

Late Triassic to Early Jurassic age (~220-185 Ma) intrusions comprise one of the most widespread and volumetrically significant plutonic suites in central and western Yukon, and eastern Alaska, but have received very limited study thus far. A new research project has been initiated that will examine the temporal, geochemical and petrotectonic evolution of this magmatic event, and the nature and

J. K. Mortensen; K. Emon; S. T. Johnston; C. J. R. Hart

101

Plate tectonic trigger of changes in pCO2 and climate in the Oxfordian (Late Jurassic): Carbon isotope and modeling evidence  

E-print Network

in the C-isotope record. A prominent mid-Oxfordian positive excursion in bulk carbonate carbon isotope Tethys realm. In this study we present new bulk organic matter C-isotope data (13 Corg) from northwestern: carbon isotopes; pCO2; climate; carbon cycle; model simulation 1. Introduction The Late Jurassic carbon

Gilli, Adrian

102

Palaeoenvironment of the Late Triassic (Rhaetian) and Early Jurassic (Hettangian) Mecsek Coal Formation (south Hungary): implications from macro- and microfloral assemblages  

Microsoft Academic Search

The changes in early Mesozoic land plant communities, their vegetation patterns and vegetation dynamics are still only poorly\\u000a understood, mainly because of the lack of integrated studies on fossil plant macroremains and palynomorphs. The Early Jurassic\\u000a represents a major recovery phase of marine and terrestrial ecosystems after one of the biggest mass extinction events in\\u000a Earth’s history at the end

Annette E. Götz; Katrin Ruckwied; Maria Barbacka

2011-01-01

103

Abelisauridae (Dinosauria: Theropoda) from the Late Jurassic of Portugal and dentition-based phylogeny as a contribution for the identification of isolated theropod teeth.  

PubMed

Theropod dinosaurs form a highly diversified clade, and their teeth are some of the most common components of the Mesozoic dinosaur fossil record. This is the case in the Lourinhã Formation (Late Jurassic, Kimmeridgian-Tithonian) of Portugal, where theropod teeth are particularly abundant and diverse. Four isolated theropod teeth are here described and identified based on morphometric and anatomical data. They are included in a cladistic analysis performed on a data matrix of 141 dentition-based characters coded in 60 taxa, as well as a supermatrix combining our dataset with six recent datamatrices based on the whole theropod skeleton. The consensus tree resulting from the dentition-based data matrix reveals that theropod teeth provide reliable data for identification at approximately family level. Therefore, phylogenetic methods will help identifying theropod teeth with more confidence in the future. Although dental characters do not reliably indicate relationships among higher clades of theropods, they demonstrate interesting patterns of homoplasy suggesting dietary convergence in (1) alvarezsauroids, therizinosaurs and troodontids; (2) coelophysoids and spinosaurids; (3) compsognathids and dromaeosaurids; and (4) ceratosaurids, allosauroids and megalosaurids.        Based on morphometric and cladistic analyses, the biggest tooth from Lourinhã is referred to a mesial crown of the megalosaurid Torvosaurus tanneri, due to the elliptical cross section of the crown base, the large size and elongation of the crown, medially positioned mesial and distal carinae, and the coarse denticles. The smallest tooth is identified as Richardoestesia, and as a close relative of R. gilmorei based on the weak constriction between crown and root, the "eight-shaped" outline of the base crown and, on the distal carina, the average of ten symmetrically rounded denticles per mm, as well as a subequal number of denticles basally and at mid-crown. Finally, the two medium-sized teeth belong to the same taxon and exhibit pronounced interdenticular sulci between distal denticles, hooked distal denticles for one of them, an irregular enamel texture, and a straight distal margin, a combination of features only observed in abelisaurids. They provide the first record of Abelisauridae in the Jurassic of Laurasia and one of the oldest records of this clade in the world, suggesting a possible radiation of Abelisauridae in Europe well before the Upper Cretaceous. PMID:24869965

Hendrickx, Christophe; Mateus, Octávio

2014-01-01

104

Seasonality in low latitudes during the Oxfordian (Late Jurassic) reconstructed via high-resolution stable isotope analysis of the oyster Actinostreon marshi (J. Sowerby, 1814) from the Kachchh Basin, western India  

NASA Astrophysics Data System (ADS)

A high-resolution stable isotope (?18O, ?13C) analysis of a specimen of the oyster Actinostreon marshi (J. Sowerby, 1814) from the Lower Oxfordian of the Kachchh Basin in western India was used to reconstruct average seasonal temperatures over a consecutive time interval of 10 years. The recorded temperatures during this period varied around a mean of 13 °C (maximum: 15.1 °C; minimum: 11.4 °C) with a generally low seasonality between 1 and 3 °C. Such weak seasonal changes can be expected from a subtropical palaeolatitude between 25° and 30°S. However, the low average temperatures are in contrast to studies on broadly contemporaneous fossils from Europe and the southern Malagasy Gulf which point to much warmer conditions in these areas. It is therefore proposed that the low temperatures in the Kachchh Basin are caused by upwelling currents which influenced the north-western coast of India during the Late Jurassic.

Alberti, Matthias; Fürsich, Franz T.; Pandey, Dhirendra K.

2013-07-01

105

Paleomagnetism of the Middle-Late Jurassic to Cretaceous red beds from the Peninsular Thailand: Implications for collision tectonics  

NASA Astrophysics Data System (ADS)

Jurassic to Cretaceous red sandstones were sampled at 33 sites from the Khlong Min and Lam Thap formations of the Trang Syncline (7.6°N, 99.6°E), the Peninsular Thailand. Rock magnetic experiments generally revealed hematite as a carrier of natural remanent magnetization. Stepwise thermal demagnetization isolates remanent components with unblocking temperatures of 620-690 °C. An easterly deflected declination ( D = 31.1°, I = 12.2°, ?95 = 13.9°, N = 9, in stratigraphic coordinates) is observed as pre-folding remanent magnetization from North Trang Syncline, whereas westerly deflected declination ( D = 342.8°, I = 22.3°, ?95 = 12.7°, N = 13 in geographic coordinates) appears in the post-folding remanent magnetization from West Trang Syncline. These observations suggest an occurrence of two opposite tectonic rotations in the Trang area, which as a part of Thai-Malay Peninsula received clockwise rotation after Jurassic together with Shan-Thai and Indochina blocks. Between the Late Cretaceous and Middle Miocene, this area as a part of southern Sundaland Block experienced up to 24.5° ± 11.5° counter-clockwise rotation with respect to South China Block. This post-Cretaceous tectonic rotation in Trang area is considered as a part of large scale counter-clockwise rotation experienced by the southern Sundaland Block (including the Peninsular Malaysia, Borneo and south Sulawesi areas) as a result of Australian Plate collision with southeast Asia. Within the framework of Sundaland Block, the northern boundary of counter-clockwise rotated zone lies between the Trang area and the Khorat Basin.

Yamashita, Itaru; Surinkum, Adichat; Wada, Yutaka; Fujihara, Makoto; Yokoyama, Masao; Zaman, Haider; Otofuji, Yo-ichiro

2011-02-01

106

Highly extended oceanic lithosphere: The basement and wallrocks for the Late Jurassic Rogue-Chetco oceanic arc, Oregon Klamath Mountains  

SciTech Connect

The superbly preserved, coeval Late Jurassic Rogue-Chetco oceanic arc and Josephine inter-arc basin exposed in the western Jurassic belt of the Oregon Klamath Mountains provide a unique opportunity to (1) directly observe the oceanic lithosphere upon which this oceanic arc was constructed, and (2) gain a better understanding of the pre-accretionary dynamic processes that shape oceanic arc and inter-arc basin lithosphere. Field relations exposed in the Roque, Illinois, and Chetco River areas show that (1) plutonic and volcanic rocks of the Rogue-Chetco arc both intruded and conformably overlapped fragmented composite blocks of oceanic crust and serpentinized, dike-filled depleted mantle rocks; and (2) arc growth occurred during regional oblique extension of the oceanic lithosphere resulting in the extreme fragmentation of oceanic crustal rocks and the local exposure of serpentinized mantle rocks on the sea floor. The Rogue-Chetco overlap sequence consists of rhythmically bedded volcanogenic turbidites, chert, argillite, and local deposits of polymict basal breccias. The clasts which comprise the distinctive basal breccias indicate derivation from a dominantly ophiolitic crust and serpentinized mantle source. Source materials for the basal breccias comprise the basement and wallrocks for the Roque-Chetco arc and consist of (1) rifted fragments of western Paleozoic and Triassic belt rocks (Yule and others, 1991) cut by heterogeneous mafic complexes inferred to represent early Josephine age rifting at approximately 165 Ma, (2) fault bounded blocks of massive gabbro, sheeted mafic dikes, pillow lava and breccia overlain by Callovian age chert, and (3) serpentinized depleted mantle peridotite cut by multiple generation of mafic and intermediate dikes. The basement rock types all share a pervasive brittle fragmentation and hydrothermal alteration history that is conspicuously absent in the arc volcanic and plutonic rocks.

Yule, J.D.; Saleeby, J.B.

1993-04-01

107

Middle Jurassic trace fossils from the Ridang Formation in Sajia County, South Tibet, and their palaeoenvironmental significance  

Microsoft Academic Search

An ichnofauna consisting of 18 ichnospecies (one of them new) in 14 ichnogenera are described for the first time from the\\u000a Middle Jurassic Ridang Formation in Sajia County, South Tibet. The ichnofauna can be subdivided into two ichnoassemblages\\u000a in ascending stratigraphic order: the Palaeophycus–Megagrapton ichnoassemblage in the lower and middle parts of the Ridang Formation, followed by the Cosmorhaphe–Nereites–Paleodictyon ichnoassemblage

Xionghua Zhang; G. R. Shi; Yiming Gong

2008-01-01

108

Trace fossils from Jurassic lacustrine turbidites of the anyao formation (Central China) and their environmental and evolutionary significance  

Microsoft Academic Search

The Lower Jurassic Anyao Formation crops out near Jiyuan city, western Henan Province, central China. It is part of the infill of the nonmarine early Mesozoic Jiyuan?Yima Basin. In the Jiyuan section, this unit is about 100 m thick and consists of laterally persistent, thin and thick?bedded turbidite sandstones and mudstones displaying complete and base?or top?absent Bouma sequences, and thick?bedded

Luis Alberto Buatois; Maria Gabriela Mângano; Xiantao Wu; Guocheng Zhang

1996-01-01

109

New geochronologic constraints on Early, Middle, and Late Jurassic orogenesis in the Klamath Mountains  

SciTech Connect

More than 40 new Ar/Ar ages, in conjunction with radiometric data published by many other authors, allow improved recognition of the spatial and temporal ranges of magmatic, metamorphic and deformational events associated with the formation of continental crust in the Klamath Mountains. Magmatism in earliest Jurassic time, [approx]200 Ma, is now recognized to have been widespread. Volcanoplutonic arcs of this age are present in upper levels of the Rattlesnake Creek terrane and in lower levels of the North Fork/Salmon River terrane. Roughly 200 Ma metaplutonic rocks are also found in the basement of the Rogue/Chetco arc, Preston Peak mafic complex, and Lems Ridge olistostrome. From 167--155 Ma, magmatic and structural extension occurred along a NW-SE corridor restricted to the northern Klamaths. Igneous rocks include the Wooley Creek, Preston Peak, Josephine, and Rogue/Chetco suites, and the Marble Mountains fault may represent a contemporaneous normal fault. The southern edge of the extended corridor is the Salmon tectonic line of Irwin (1985), but the northern boundary has not been recognized or named. Both boundaries were presumably transfer zones accommodating differential subhorizontal extension, but many details are still to be determined. The Siskiyou and Nevadan orogenies can no longer be assigned specific, narrow time windows and may have outlived their usefulness as currently defined. Enough geochronologic data are now available to consider the ages and characteristics of specific plutons, deformation fabrics, and metamorphic minerals in individual areas, rather than assuming such events occur throughout the orogen within specific time ranges.

Donato, M.M. (Geological Survey, Menlo Park, CA (United States)); Hacker, B.R.; McWilliams, M.O.

1993-04-01

110

Approaching trophic structure in Late Jurassic neritic shelves: A western Tethys example from southern Iberia  

NASA Astrophysics Data System (ADS)

The palaeoenvironmental conditions and trophic structure of a mid-outer neritic biota (microfossils, mainly forams, and macroinvertebrate assemblages) have been approached in middle Oxfordian-lowermost Kimmeridgian deposits from the Prebetic Zone (Betic Cordillera) in south-eastern Spain. According to relationships between fossil assemblages and lithofacies, a general seaward trend is identified which displays decreasing sedimentation rates and nutrient inputs, but increasing substrate consistency and presumably depth. Midshelf, terrigenous-rich deposits in the External Prebetic relate to the highest sedimentation rates and nutrient availability. These two parameters correlate with the highest content in vagile-benthic, calcareous perforate, epifaunal forams, as well as with potentially deep infaunal forams and infaunal macroinvertebrates. Outer-shelf lumpy deposits in the Internal Prebetic show the lowest sedimentation rates and nutrient availability and the highest records for macro-micro nektonics and planktics. In contrast, vagile-benthic, calcareous perforate epifaunal and potentially deep infaunal forams are scarcer in the midshelf environments. Colonial encrusting forams, benthic microbial communities and sessile benthic macro-invertebrates increase from the middle to outer shelf. Trophic-analysis structuring through the integration of benthic microbial communities, foraminiferal and macroinvertebrate fossil assemblages makes it possible to interpret: (a) a trophic-level frame composed of producers and primary and secondary consumers; (b) a main trophic-group differentiation in suspension-feeders, detritus-feeders, browsers, grazers, carnivores and scavengers; (c) a preliminary approach to food-chain structure supported by suspension-feeders, deposit-feeders and predators (active prey-selection carnivores); and (d) a food-pyramid model, which takes into account both recorded fossils and envisaged —i.e., ecologically inferred-organisms.

Olóriz, Federico; Reolid, Matías; Rodríguez-Tovar, Francisco J.

2006-11-01

111

Supporting Information Late Paleocene fossils from the Cerrejn Formation, Colombia, are the earliest record of  

E-print Network

of coal marks the lower 50 m of the Cerrejón Formation. Sedimentary structures in this interval includeSupporting Information Late Paleocene fossils from the Cerrejón Formation, Colombia of the Cerrejón Formation and stratigraphic positions of the megafloral collections (Fig. S1); 2) source

Lyons, S. Kathleen

112

Author's personal copy Fossil wood in coal-forming environments of the late Paleoceneearly Eocene  

E-print Network

Sequoioideae Taxodiaceae The early Cenozoic Chickaloon Formation is the main coal-bearing sequence in southAuthor's personal copy Fossil wood in coal-forming environments of the late Paleocene­early Eocene Chickaloon Formation Christopher J. Williams a, , Kyle D. Trostle a,b , David Sunderlin c a Department

Williams, Christopher J.

113

Late Cretaceous Extreme Polar Warmth recorded by Vertebrate Fossils from the High Canadian Arctic  

NASA Astrophysics Data System (ADS)

A vertebrate fossil assemblage from Late Cretaceous (Coniacian-Turonian, ~92 to 86 Ma) rocks on Axel Heiberg Island in the High Canadian Arctic reflects what was once a diverse community of freshwater fishes and reptiles. Paleomagnetic data indicate a paleolatitude of ~71° N for the site; the fossils are from non-migratory fauna, so they can provide insight into Late Cretaceous polar climate. The fossil assemblage includes large (> 2.4 m long) champsosaurs (extinct crocodilelike reptiles). The presence of large champsosaurs suggests a mean annual temperature > 14 °C (and perhaps as great as 25 °C). Here we summarize findings and analyses following the discovery of the fossil-bearing strata in 1996. Examination of larger fish elements, isolated teeth and SEM studies of microstructures indicates the presence of lepisosteids, amiids and teleosts (Friedman et al., 2003) Interestingly, the only other known occurrence of amiids and lepisosteids, fossil or recent, are from intervals of extreme warmth during the Tertiary. Turtles present in the assemblage include Boreralochelys axelheibergensis, a generically indeterminate eucryptodire and a trioychid (Brinkman and Tarduno, 2005). The level of turtle diversity is also comparable to mid-latitude assemblages with a mean annual paleotemperature of at least 14 °C. A large portion of the champsosaur fossil assemblage is comprised of elements from subadults. This dominance of subadults is similar to that seen from low latitude sites. Because of the sensitivity of juveniles to ice formation, the make-up of the Arctic champsosaur population further indicates that the Late Cretaceous saw an interval of extreme warmth and low seasonality. We note the temporal coincidence of these fossils with volcanism at large igneous provinces (including high Arctic volcanism) and suggest that a pulse in volcanic carbon dioxide emissions helped cause the global warmth.

Vandermark, D.; Tarduno, J. A.; Brinkman, D.

2006-12-01

114

Phytogeographical Implication of Bridelia Will. (Phyllanthaceae) Fossil Leaf from the Late Oligocene of India  

PubMed Central

Background The family Phyllanthaceae has a predominantly pantropical distribution. Of its several genera, Bridelia Willd. is of a special interest because it has disjunct equally distributed species in Africa and tropical Asia i.e. 18–20 species in Africa-Madagascar (all endemic) and 18 species in tropical Asia (some shared with Australia). On the basis of molecular phylogenetic study on Bridelia, it has been suggested that the genus evolved in Southeast Asia around 33±5 Ma, while speciation and migration to other parts of the world occurred at 10±2 Ma. Fossil records of Bridelia are equally important to support the molecular phylogenetic studies and plate tectonic models. Results We describe a new fossil leaf of Bridelia from the late Oligocene (Chattian, 28.4–23 Ma) sediments of Assam, India. The detailed venation pattern of the fossil suggests its affinities with the extant B. ovata, B. retusa and B. stipularis. Based on the present fossil evidence and the known fossil records of Bridelia from the Tertiary sediments of Nepal and India, we infer that the genus evolved in India during the late Oligocene (Chattian, 28.4–23 Ma) and speciation occurred during the Miocene. The stem lineage of the genus migrated to Africa via “Iranian route” and again speciosed in Africa-Madagascar during the late Neogene resulting in the emergence of African endemic clades. Similarly, the genus also migrated to Southeast Asia via Myanmar after the complete suturing of Indian and Eurasian plates. The emergence and speciation of the genus in Asia and Africa is the result of climate change during the Cenozoic. Conclusions On the basis of present and known fossil records of Bridelia, we have concluded that the genus evolved during the late Oligocene in northeast India. During the Neogene, the genus diversified and migrated to Southeast Asia via Myanmar and Africa via “Iranian Route”. PMID:25353345

Srivastava, Gaurav; Mehrotra, R.C.

2014-01-01

115

DISCOVERY OF DESEADAN FOSSILS IN THE UPPER MOQUEGUA FORMATION (LATE OLIGOCENE--?EARLY MIOCENE) OF SOUTHERN PERU  

E-print Network

NOTE DISCOVERY OF DESEADAN FOSSILS IN THE UPPER MOQUEGUA FORMATION (LATE OLIGOCENE--?EARLY MIOCENE. The Deseadan SALMA fossils were found in the Upper Mo- quegua Formation at the summits of Cerro Pan de Azúcar OF THE UPPER MOQUEGUA FORMATION The most common fossils so far encountered in the Upper Moquegua Formation

Sargis, Eric J.

116

Late Jurassic to Early Cretaceous black shale formation and paleoenvironment in high northern latitudes: Examples from the Norwegian-Greenland Seaway  

Microsoft Academic Search

The Late Jurassic to Early Cretaceous (Volgian-Ryazanian) was a period of a second-order sea-level low stand, and it provided excellent conditions for the formation of shallow marine black shales in the Norwegian-Greenland Seaway (NGS). IKU Petroleum Research drilling cores taken offshore along the Norwegian shelf were investigated with geochemical and microscopic approaches to (1) determine the composition of the organic

Uwe Langrock; Ruediger Stein; Marcus Lipinski; Hans-Juergen Brumsack

2003-01-01

117

A crustal section of an intra-oceanic island arc: The Late Jurassic-Early Cretaceous Guanajuato magmatic sequence, central Mexico  

Microsoft Academic Search

The Late Jurassic-Early Cretaceous Alisitos-Teloloapan intra-oceanic arc, which extends along the Pacific coast of Mexico, is overlain by the extensive thick calc-alkaline Tertiary volcanics of the Sierra Madre Occidental. In central-southern Mexico this arc can be divided in to two major units. Its base, which is mainly exposed in the Guanajuato-Leon area, consists of a volcano-plutonic assemblage refered to as

Henriette Lapierre; Luis Enrique Ortiz; Wafa Abouchami; Olivier Monod; Christian Coulon; Jean-Louis Zimmermann

1992-01-01

118

Behaviour of nuclides and U-series disequilibrium in clayey sediments: application to the Late Jurassic record from the eastern Paris basin  

Microsoft Academic Search

We present a record of U-series disequilibrium covering the Callovo-Oxfordian-Thitonian times of the Late Jurassic carbonated platform from the eastern part of the Paris basin. The Callovo-Oxfordian clayey layer is the potential host rock for reconnaissance work carried out by Andra (e.g., Agence Nationale de Gestion des Déchets Radioactifs) in eastern France, the objective of which is the designing and

J. Casanova; Ph. Négrel; C. Innocent; J. Brulhet

2003-01-01

119

A NEW LATE MIOCENE SPECIES OF PARACOLOBUS AND OTHER CERCOPITHECOIDEA (MAMMALIA: PRIMATES) FOSSILS FROM LEMUDONG'O, KENYA  

Microsoft Academic Search

The Colobinae (Mammalia: Primates) are relatively unknown from the middle to late Miocene of eastern Africa. When they appear in the Pliocene fossil record they are unambiguous and fairly diverse taxonomically, geographically, and ecologically. The primate fauna from the late Miocene of Lemudong'o is dominated by colobines and therefore represents one of the richest fossil assemblages yet published of this

LESLEA J. HLUSKO

120

Dike orientations in the late jurassic independence dike swarm and implications for vertical-axis tectonic rotations in eastern California  

USGS Publications Warehouse

Analysis of the strikes of 3841 dikes in 47 domains in the 500-km-long Late Jurassic Independence dike swarm indicates a distribution that is skewed clockwise from the dominant northwest strike. Independence dike swarm azimuths tend to cluster near 325?? ?? 30??, consistent with initial subparallel intrusion along much of the swarm. Dike azimuths in a quarter of the domains vary widely from the dominant trend. In domains in the essentially unrotated Sierra Nevada block, mean dike azimuths range mostly between 300?? and 320??, with the exception of Mount Goddard (247??). Mean dike azimuths in domains in the Basin and Range Province in the Argus, Inyo, and White Mountains areas range from 291?? to 354?? the mean is 004?? in the El Paso Mountains. In the Mojave Desert, mean dike azimuths range from 318?? to 023??, and in the eastern Transverse Ranges, they range from 316?? to 051??. Restoration for late Cenozoic vertical-axis rotations, suggested by paleodeclinations determined from published studies from nearby Miocene and younger rocks, shifts dike azimuths into better agreement with azimuths measured in the tectonically stable Sierra Nevada. This confirms that vertical-axis tectonic rotations explain some of the dispersion in orientation, especially in the Mojave Desert and eastern Transverse Ranges, and that the dike orientations can be a useful if imperfect guide to tectonic rotations where paleomagnetic data do not exist. Large deviations from the main trend of the swarm may reflect (1) clockwise rotations for which there is no paleomagnetic evidence available, (2) dike intrusions of other ages, (3) crack filling at angles oblique or perpendicular to the main swarm, (4) pre-Miocene rotations, or (5) unrecognized domain boundaries between dike localities and sites with paleomagnetic determinations. ?? 2008 The Geological Society of America.

Hopson, R. F.; Hillhouse, J. W.; Howard, K. A.

2008-01-01

121

The sponge genus Brachiaster (Pachastrellidae, Demospongiae) and its first known fossil representative, from the late Eocene of southwestern Australia  

Microsoft Academic Search

Pisera, A. & Bitner, M.A., December, 2007. The sponge genus Brachiaster (Pachastrellidae, Demospongiae) and its first known fossil representative, from the late Eocene of southwestern Australia. Alcheringa 31, 365?373. ISSN 0311-5518.The pachastrellid genus Brachiaster Wilson (Pachastrellidae, Demospongiae, Porifera) has had until now no known fossil representatives. Here we describe its first known fossil representative from the late Eocene of southwestern

Andrzej Pisera; Maria Aleksandra Bitner

2007-01-01

122

A Jurassic mammal from South America  

Microsoft Academic Search

The Jurassic period is an important stage in early mammalian evolution, as it saw the first diversification of this group, leading to the stem lineages of monotremes and modern therian mammals. However, the fossil record of Jurassic mammals is extremely poor, particularly in the southern continents. Jurassic mammals from Gondwanaland are so far only known from Tanzania and Madagascar, and

Oliver W. M. Rauhut; Thomas Martin; Edgardo Ortiz-Jaureguizar; Pablo Puerta

2002-01-01

123

The Science Behind Jurassic Park  

NSDL National Science Digital Library

"The Science Behind Jurassic Park" is an html document describing how world renowned paleontologist Jack Horner is using computers and CAT scan machines to peer inside 30 million year old dinosaur fossils.

124

Fossils  

NSDL National Science Digital Library

Students discover the science of paleontology and the fossilization process. Why should we study fossils? Use your KWL chart to record information you have learned and anything else you want to know about. First read about the fossils of birds and what we learn from them. Then discover the Fossilization Process. Find out if there are still new dinosaurs to be discovered. Watch paleontologists hunt for ...

Tassihj

2009-10-21

125

The Cranial Osteology and Feeding Ecology of the Metriorhynchid Crocodylomorph Genera Dakosaurus and Plesiosuchus from the Late Jurassic of Europe  

PubMed Central

Background Dakosaurus and Plesiosuchus are characteristic genera of aquatic, large-bodied, macrophagous metriorhynchid crocodylomorphs. Recent studies show that these genera were apex predators in marine ecosystems during the latter part of the Late Jurassic, with robust skulls and strong bite forces optimized for feeding on large prey. Methodology/Principal Findings Here we present comprehensive osteological descriptions and systematic revisions of the type species of both genera, and in doing so we resurrect the genus Plesiosuchus for the species Dakosaurus manselii. Both species are diagnosed with numerous autapomorphies. Dakosaurus maximus has premaxillary ‘lateral plates’; strongly ornamented maxillae; macroziphodont dentition; tightly fitting tooth-to-tooth occlusion; and extensive macrowear on the mesial and distal margins. Plesiosuchus manselii is distinct in having: non-amblygnathous rostrum; long mandibular symphysis; microziphodont teeth; tooth-crown apices that lack spalled surfaces or breaks; and no evidence for occlusal wear facets. Our phylogenetic analysis finds Dakosaurus maximus to be the sister taxon of the South American Dakosaurus andiniensis, and Plesiosuchus manselii in a polytomy at the base of Geosaurini (the subclade of macrophagous metriorhynchids that includes Dakosaurus, Geosaurus and Torvoneustes). Conclusions/Significance The sympatry of Dakosaurus and Plesiosuchus is curiously similar to North Atlantic killer whales, which have one larger ‘type’ that lacks tooth-crown breakage being sympatric with a smaller ‘type’ that has extensive crown breakage. Assuming this morphofunctional complex is indicative of diet, then Plesiosuchus would be a specialist feeding on other marine reptiles while Dakosaurus would be a generalist and possible suction-feeder. This hypothesis is supported by Plesiosuchus manselii having a very large optimum gape (gape at which multiple teeth come into contact with a prey-item), while Dakosaurus maximus possesses craniomandibular characteristics observed in extant suction-feeding odontocetes: shortened tooth-row, amblygnathous rostrum and a very short mandibular symphysis. We hypothesise that trophic specialisation enabled these two large-bodied species to coexist in the same ecosystem. PMID:23028723

Young, Mark T.; Brusatte, Stephen L.; de Andrade, Marco Brandalise; Desojo, Julia B.; Beatty, Brian L.; Steel, Lorna; Fernandez, Marta S.; Sakamoto, Manabu; Ruiz-Omenaca, Jose Ignacio; Schoch, Rainer R.

2012-01-01

126

Late Silurian trace fossils from the Melbourne Formation, Studley Park, Victoria, southeastern Australia  

Microsoft Academic Search

An ichnoassemblage of 10 ichnospecies is described for the first time from the Late Silurian Melbourne Formation at Studley Park, Victoria, southeastern Australia. The ichnofauna is preserved in a typical deep-water turbidite succession of alternating thin- to thick-bedded sandstone and thin- to medium-bedded mudrocks. Trace fossils observed within the study site have been assigned to three main ichnofacies. Ichnofacies 1

G. R. Shi; Yi-Ming Gong; A. Potter

2009-01-01

127

Recognition and analysis of fossil soils developed on alluvium: a Late Ordovician example  

SciTech Connect

A series of fossil soils in alluvial red beds from the upper Juniata Formation, near Potters Mills, Pennsylvania, provide evidence of soil forming processes during the late Ordovician. Paleogeographic and facies considerations indicate that the fossil soils formed floodplains west of the Taconic uplift. Most studies of paleosols of this age or older have considered soils developed on metamorphic or igneous basement rock. Alluvial fossil soils provide evidence of conditions during shorter intervals of weathering without problems of overprinting by successive and different weathering regimes. They can be recognized by the presence of trace fossils and development of soil horizonation and structure. Problems associated with such fossil soils include establishing the nature of the parent material and distinguishing clay formation in the soil from originally deposited fining upwards cycles. These difficulties can be overcome by comparing paleosols of different development, as indicated by degree of ferruginization, density of trace fossils, amount of clay, and abundance and size of caliche nodules. In modern soils, caliche forms in alkaline conditions under which TiO/sub 2/ is stable. Gains and losses of oxides in gm/cc relative to TiO/sub 2/ in a strongly developed paleosol were compared with those of a weakly developed paleosol, taken to approximate the compositional range of the parent material. Anomalous enrichment in K/sub 2/O has been documented in other ancient fossil soils. Both XRD studies and a strong correlation between K/sub 2/O and Al/sub 2/O/sub 3/ are evidence that most of the potassium is contained in illite.

Feakes, C.R.; Retallack, G.J.

1985-01-01

128

Fossils  

NSDL National Science Digital Library

Fossils is an activity for grades 1-2 that enables students to apply their interest in dinosaurs to discovering how fossils tell us about our past. As a result of this activity, the students will be able to: tell a friend or parent who a paleontologist is and what he does; explain what a fossil is; explain how we use fossils to learn about the past; and make a fossil using clay, plaster of paris, and some sort of molding object such as a shell, leaf, bone, etc. A suggested extension of this activity is turning it into an archaeological "dig" by burying objects in plaster of paris and then using dull instruments to dig for the "fossils."

1998-01-01

129

1, 119, 2006 Jurassic seasons  

E-print Network

eED 1, 1­19, 2006 Jurassic seasons C. L´ecuyer and H. Bucher Title Page Abstract Introduction reviewed discussion forum of eEarth Stable isotope compositions of a late Jurassic ammonite shell: a record Correspondence to: C. L´ecuyer (clecuyer@univ-lyon1.fr) 1 #12;eED 1, 1­19, 2006 Jurassic seasons C. L

Paris-Sud XI, Université de

130

Late glacial climate estimates for southern Nevada: The ostracode fossil record  

SciTech Connect

Climate change plays an important role in determining as possible long term hydrological performance of the potential high level nuclear waste repository within Yucca Mountain, Nevada. Present-day global circulation results in this region having an arid to semi-arid climate characterized by hot and relatively dry summers. Global circulation during the late glacial (about 14 to 20 ka) was very different from the present-day. Preliminary study of late-glacial fossil ostracodes from {open_quotes}marsh deposits{close_quotes} in the upper Las Vegas Valley suggests mean annual precipitation may have been four times higher, while mean annual temperature may have been about 10{degrees}C cooler than today. A major difference between present-day and late-glacial climate was likely the existence of cooler, cloudier, and wetter summers in the past.

Forester, R.M. [Geological Survey, Denver, CO (United States); Smith, A.J. [Kent State Univ., OH (United States)

1995-10-01

131

Fossils  

NSDL National Science Digital Library

4th Grade Science Standard 4: Students will understand how fossils are formed, where they may be found in Utah, and how they can be used to make inferences. DISCOVERING FOSSILS!!

141

Carbon-isotope record of the Early Jurassic (Toarcian) Oceanic Anoxic Event from fossil wood and marine carbonate (Lusitanian Basin, Portugal)  

NASA Astrophysics Data System (ADS)

The Toarcian Oceanic Anoxic Event (OAE) in the Early Jurassic (˜ 183 Ma ago) was characterized by widespread near-synchronous deposition of organic-rich shales in marine settings, as well as perturbations to several isotopic systems. Characteristically, two positive carbon-isotope excursions in a range of materials are separated by an abrupt negative shift. Carbon-isotope profiles from Toarcian fossil wood collected in England and Denmark have previously been shown to exhibit this large drop (˜ - 7‰) in ?13C values, interpreted as due to an injection of isotopically light CO 2 into the ocean-atmosphere system. However, the global nature of this excursion has been challenged on the basis of carbon-isotope data from nektonic marine molluscs (belemnites), which exhibit heavier than expected carbon-isotope values. Here we present new data, principally from fossil wood and bulk carbonate collected at centimetre scale from a hemipelagic section at Peniche, coastal Portugal. This section is low in organic carbon (average TOC = ˜ 0.5%), and the samples should not have suffered significant diagenetic contamination by organic carbon of marine origin. The carbon-isotope profile based on wood shows two positive excursions separated by a large and abrupt negative excursion, which parallels exactly the profile based on bulk carbonate samples from the same section, albeit with approximately twice the amplitude (˜ - 8‰ in wood versus ˜ - 3.5‰ in carbonate). These data indicate that the negative carbon-isotope excursion affected the atmosphere and, by implication, the global ocean as well. The difference in amplitude between terrestrial organic and marine carbonate curves can be explained by greater water availability in the terrestrial environment during the negative excursion, for which there is independent evidence from marine osmium-isotope records and, plausibly, changes in atmospheric CO 2 content, for which independent evidence is also available. The Peniche succession is also notable for the occurrence of re-deposited sediments: their lowest occurrence coincides with the base of the negative excursion and their highest occurrence coincides with its top. Thus, slope instability and sediment supply could have been strongly linked to the global environmental perturbation, an association that may misleadingly simulate the effects of sea-level fall.

Hesselbo, Stephen P.; Jenkyns, Hugh C.; Duarte, Luis V.; Oliveira, Luiz C. V.

2007-01-01

142

Fossils  

NSDL National Science Digital Library

Paleontologists seldom have the good fortune to find a complete set of remains of an ancient organism that is wholly intact. For instance, the discovery of a frozen woolly mammoth carcass, preserved hair and all, was a truly rare event. More common are discoveries of incomplete remains, such as bones, teeth, or hair, and trace fossils, such as footprints or leaf impressions, which indicate an organism once existed even though its actual remains have not been found. This slide presentation reveals the variety of forms that fossils take, as well as examples of the kinds of life whose remains have been preserved. A background essay and discussion questions are included.

2011-05-17

143

Plagiogranite magmatism in the frontal part of Pekulney segment of Late Jurassic-Early Cretaceous Pekulney-Zolotogorskaya paleoarc  

NASA Astrophysics Data System (ADS)

PLAGIOGRANITE MAGMATISM IN THE FRONTAL PART OF PEKULNEY SEGMENT OF LATE JURASSIC-EARLY CRETACEOUS PEKULNEY-ZOLOTOGORSKAYA PALEOARC M.V.Luchitskaya (1), O.L.Morozov (1), S.A.Palandzhyan (2) (1) Geological Institute, Russian Academy of Sciences, Russia, Moscow, (2) Institute of Lithosphere of Marginal and Inner Seas, Russian Academy of Sciences, Russia, Moscow luchitskaya@geo.tv-sign.ru/Fax: (095) 2310443 Pekulney-Zolotogorskaya system of Central Chukotka is located at the junction of Verkhoynsk-Chukotka Mesozoides and Koryak-Kamchatka accretionary region. In the fold-and-thrust structure of its Pekulney segment autochthone, allochthone and neoautochthone are reconstructed. Autochtone is J3-K1 volcano-plutonic island arc complex and its pre-Mz heterogeneous basement (Pz3-Mz1 volcano-plutonic complex and Precambrian (?) metabasite-gabbroic complex). Allochtone is composed of J2-K1 siliceous-volcanic complex (a fragment of an oceanic basin crust) and K1 terrigeneous-tuffaceous-siliceous complex, formed on the inner trench slope). Neoautochthone is composed of post-K1h formations, overlying with unconfirmity the deformed complexes of different age and genesis. Plagiogranites are located at the contact of slices composed of J2-K1 siliceous-volcanic deposits and K1 terrigeneous-tuffaceous-siliceous complex. They form dikes in the matrix of terrigeneous-tuffaceous-siliceous complex and in the rocks of siliceous-volcanic complex and are also observed as a different size fragments in the former. Part of plagiogranites is dinamothermally metamorphosed together with host siliceous-volcanic deposits. The age of plagiogranites is post-K1nc according to geological data. Plagiogranites are low-K, low-Al rocks, K/Na=0.07-0.46. They fall in the trondhjemites field on the Ab-An-Or diagram and follow gabbro-trondhjemite trend. They fall in VAG field in the Rb Y+Nb diagram and in the supra-subduction related rocks field in the (Nb/Zr)n Zr diagram. ORG-normalized patterns are characterized by Ta, Nb negative anomalies. REE patterns of plagiogranites comprise two groups: more fractionated with positive Eu-anomaly and less fractionated with negative one. The latter have adakite-like Sr/Y ratios. The structure of Pekulney segment of paleoarc in K1 time, structural position of plagiogranites, permanent character of their intrusion and their geochemistry, allow to suppose two models of plagiogranite melts formation: melting of metabasite complexes in the pre-Mz heterogeneous arc basement and fractional crystallization of tholeiite-basalt melts. Acid melts migrated throuh accretional structure in the arc frontal part. Geochemical modelling using REE show that these two paths of plagiogranite formation may took place. Supported by RFBR grant N 01-05-64469.

Luchitskaya, M. V.; Morozov, O. L.; Palandzhyan, S. A.

2003-04-01

144

High resolution reservoir architecture of late Jurassic Haynesville ramp carbonates in the Gladewater field, East Texas Salt Basin  

Microsoft Academic Search

The East Texas Salt Basin contains numerous gas fields within Upper Jurassic Haynesville ramp-complex reservoirs. A sequenced-keyed, high-resolution zonation scheme was developed for the Haynesville Formation in Gladewater field by integrating core description, well-log, seismic, porosity and permeability data. The Haynesville at Gladewater represents a high-energy ramp system, localized on paleotopographic highs induced by diapirism of Callovian Age Salt (Louann).

Goldhammer

1996-01-01

145

Discovery of fossil monocotyledons from Yixian Formation, western Liaoning  

Microsoft Academic Search

This is the first reports of a few fossil monocotyledons, includingLiaoxia chenii gen. et sp. nov. (belonging to Cyperaceae),Eragrosites changii gen. et sp. nov. (Gramineae) and a monocotyledonous leaf-shoot, obtained from the Late Jurassic Yixian Formation of western\\u000a Liaoning Province, NE China. These fossils are the oldest known angiosperms in the world. It may be inferred that the earliest\\u000a angiosperms

Zhengyao Cao; Shunqing Wu; Ping’an Zhang; Jieru Li

1998-01-01

146

Isotopic evidence bearing on Late Triassic extinction events, Queen Charlotte Islands, British Columbia, and implications for the duration and cause of the Triassic/Jurassic mass extinction  

USGS Publications Warehouse

Stable isotope analyses of Late Triassic to earliest Jurassic strata from Kennecott Point in the Queen Charlotte Islands, British Columbia, Canada shows the presence of two distinct and different organic carbon isotope anomalies at the Norian/Rhaetian and Rhaetian/Hettangian (=Triassic/Jurassic) stage boundaries. At the older of these boundaries, which is marked by the disappearance of the bivalve Monotis, the isotope record shows a series of short-lived positive excursions toward heavier values. Strata approaching this boundary show evidence of increasing anoxia. At the higher boundary, marked by the disappearance of the last remaining Triassic ammonites and over 50 species of radiolarians, the isotopic pattern consists of a series of short duration negative anomalies. The two events, separated by the duration of the Rhaetian age, comprise the end-Triassic mass extinction. While there is no definitive evidence as to cause, the isotopic record does not appear similar to that of the impact-caused Cretaceous/Tertiary boundary extinction. ?? 2004 Published by Elsevier B.V.

Ward, P. D.; Garrison, G. H.; Haggart, J. W.; Kring, D. A.; Beattie, M. J.

2004-01-01

147

Fossil birds from the Late Cretaceous Los Alamitos Formation, Río Negro Province, Argentina  

NASA Astrophysics Data System (ADS)

In this note we report new avian remains from the Late Cretaceous Los Alamitos Formation (Campanian-Maastrichtian) at the Los Alamitos locality, Río Negro Province, Argentina. Isolated remains referable to indeterminate Aves, ?Patagopterygiformes, indeterminate Ornithurae, cf. Hesperornithes and cf. Neornithes are described and discussed. The new genus and species Alamitornis minutus is erected to include a minute-sized and gracile bird, probably related to the non-volant ratite-like bird Patagopteryx. If correctly identified, the record of Hesperornithes may be the first for this group in the Southern Hemisphere. The Los Alamitos paleoavifauna represents one of the most diverse fossil bird assemblage from the Mesozoic of Gondwana known to date.

Agnolin, Federico L.; Martinelli, Agustín G.

2009-02-01

148

Fossil plant relative abundances indicate sudden loss of Late Triassic biodiversity in East Greenland.  

PubMed

The pace of Late Triassic (LT) biodiversity loss is uncertain, yet it could help to decipher causal mechanisms of mass extinction. We investigated relative abundance distributions (RADs) of six LT plant assemblages from the Kap Stewart Group, East Greenland, to determine the pace of collapse of LT primary productivity. RADs displayed not simply decreases in the number of taxa, but decreases in the number of common taxa. Likelihood tests rejected a hypothesis of continuously declining diversity. Instead, the RAD shift occurred over the upper two-to-four fossil plant assemblages and most likely over the last three (final 13 meters), coinciding with increased atmospheric carbon dioxide concentration and global warming. Thus, although the LT event did not induce mass extinction of plant families, it accompanied major and abrupt change in their ecology and diversity. PMID:19541995

McElwain, Jennifer C; Wagner, Peter J; Hesselbo, Stephen P

2009-06-19

149

Fossil pollen records reveal a late rise of open-habitat ecosystems in Patagonia.  

PubMed

The timing of major turnovers in terrestrial ecosystems of the Cenozoic Era has been largely interpreted from the analysis of the assumed feeding preference of extinct mammals. For example, the expansion of open-habitat ecosystems (grasslands or savannas) is inferred to have occurred earlier in Patagonia than elsewhere because of the early advent of high-crowned teeth (hypsodont) mammals ?26?Ma ago. However, the plant fossil record from Patagonia implies another evolutionary scenario. Here we show that the dominance of key open-habitat species--amaranths, Ephedra, asters and grasses--occurred during the last 10?Ma, about 15?Ma later than previously inferred using feeding/habitat ecology of extinct mammals. This late rise of open-landscapes in southern South America brings into question whether the expansion of open-habitat vegetation could have been the prime factor of high-crowned mammal diversification. PMID:23250424

Palazzesi, Luis; Barreda, Viviana

2012-01-01

150

U-Pb zircon geochronology and geochemistry of Late Jurassic basalts in Maevatanana, Madagascar: Implications for the timing of separation of Madagascar from Africa  

NASA Astrophysics Data System (ADS)

Magmatic zircon ages for the Maevatanana basalts in Madagascar indicate that Madagascar separated from Africa at 149.8 ± 2.1 Ma. Rocks produced by this basaltic magmatism associated with rifting are characterized by low SiO2 (49.6-50.3 wt.%), high total FeO (>13.9 wt.%), TiO2 (>3.7 wt.%), and P2O5 (>0.5 wt.%), and extremely high Na2O/K2O (3.08-3.27). Geochemical variations can be ascribed to significant fractional crystallization of clinopyroxene and plagioclase. The mineralogical and geochemical characteristics of the Maevatanana basalts suggest affinities with calc-alkaline basalt. Additionally the basalts have distinct ocean-island-basalt-like geochemical features that may be related to the Marion plume. We speculate that the Maevatanana basalts are the product of the Marion mantle plume related to separation of Madagascar from Africa in the Late Jurassic.

Yang, Xi-An; Chen, Yu-Chuan; Hou, Ke-Jun; Liu, Shan-Bao; Liu, Jia-Jun

2014-12-01

151

High resolution reservoir architecture of late Jurassic Haynesville ramp carbonates in the Gladewater field, East Texas Salt Basin  

SciTech Connect

The East Texas Salt Basin contains numerous gas fields within Upper Jurassic Haynesville ramp-complex reservoirs. A sequenced-keyed, high-resolution zonation scheme was developed for the Haynesville Formation in Gladewater field by integrating core description, well-log, seismic, porosity and permeability data. The Haynesville at Gladewater represents a high-energy ramp system, localized on paleotopographic highs induced by diapirism of Callovian Age Salt (Louann). Ramp crest grainstones serve as reservoirs. We have mapped the distribution of reservoir facies within a hierarchy of upward-shallowing parasequences grouped into low-frequency sequences. The vertical stacking patterns of parasequences and sequences reflect the interplay of eustasy, sediment accumulation patterns, and local subsidence (including salt movement and compaction). In this study we draw on regional relations from analogous, Jurassic systems in Mexico to constrain the stratigraphic architecture, age model, and facies model. Additionally, salt-cored Holocene, grain-rich shoals from the Persian Gulf provide excellent facies analogs. The result is a new high-resolution analysis of reservoir architecture at a parasequence scale that links reservoir facies to depositional facies. The new stratigraphy scheme demonstrates that different geographic portions of the field have markedly distinct reservoir intervals, both in terms of total pay and the sequence-stratigraphic interval within which it occurs. Results from this study are used to evaluate infill drill well potential, in well planning, for updating reservoir models, and in refining field reserve estimates.

Goldhammer, R.K. (Texas Bureau of Mines and Geology, Houston, TX (United States))

1996-01-01

152

High resolution reservoir architecture of late Jurassic Haynesville ramp carbonates in the Gladewater field, East Texas Salt Basin  

SciTech Connect

The East Texas Salt Basin contains numerous gas fields within Upper Jurassic Haynesville ramp-complex reservoirs. A sequenced-keyed, high-resolution zonation scheme was developed for the Haynesville Formation in Gladewater field by integrating core description, well-log, seismic, porosity and permeability data. The Haynesville at Gladewater represents a high-energy ramp system, localized on paleotopographic highs induced by diapirism of Callovian Age Salt (Louann). Ramp crest grainstones serve as reservoirs. We have mapped the distribution of reservoir facies within a hierarchy of upward-shallowing parasequences grouped into low-frequency sequences. The vertical stacking patterns of parasequences and sequences reflect the interplay of eustasy, sediment accumulation patterns, and local subsidence (including salt movement and compaction). In this study we draw on regional relations from analogous, Jurassic systems in Mexico to constrain the stratigraphic architecture, age model, and facies model. Additionally, salt-cored Holocene, grain-rich shoals from the Persian Gulf provide excellent facies analogs. The result is a new high-resolution analysis of reservoir architecture at a parasequence scale that links reservoir facies to depositional facies. The new stratigraphy scheme demonstrates that different geographic portions of the field have markedly distinct reservoir intervals, both in terms of total pay and the sequence-stratigraphic interval within which it occurs. Results from this study are used to evaluate infill drill well potential, in well planning, for updating reservoir models, and in refining field reserve estimates.

Goldhammer, R.K. [Texas Bureau of Mines and Geology, Houston, TX (United States)

1996-12-31

153

K/Ar chronologies of tephra units from the Middle Jurassic Sundance, and Late Early Cretaceous Mowry and Shell Creek Formations, Big Horn Basin, WY  

NASA Astrophysics Data System (ADS)

The Middle Jurassic Sundance and Late Early Cretaceous Shell Creek and Mowry Formations of the Big Horn Basin, Wyoming, contain an extensive record of altered tephra. These tephra are likely related to contemporary volcanic activity in the Sierra Nevada and various Coast Range terranes to the west and provide valuable chronometric control on the sedimentary record within a portion of the Sevier-aged and later Cordilleran foreland basin. In addition, several of these altered tephra (bentonites) provide a valuable economic resource. Despite the prominence of these strata across the basin, few isotopic ages have been reported to date. Here we present new K/Ar ages on biotite phenocrysts from those tephra occurrences as a chronometric check on samples that contained zircons with significant Pb loss, that preclude more precise U/Pb age determinations. A bulk biotite sample extracted from an altered tuff in the Lower Sundance Formation gives an age of 167.5 × 5 Ma. This tuff occurs just above a dinosaur track-bearing peritidal sequence. Bulk biotite ages from the lower Shell Creek Formation give an age of 100.3 × 3 Ma and are statistically indistinguishable from biotite grains dated at 103.1 × 3 Ma extracted from the economically important 'Clay Spur' bentonite found at the top of the Mowry Shale. This work provides important new chronometric constraints on a portion of the Medial Jurassic to Late Early Cretaceous stratigraphy of the Big Horn Basin, Wyoming, and may be useful in understanding the regional tectonics that helped shape the development of the Sevier foreland basin and Western Interior Seaway.

Jiang, H.; Meyer, E. E.; Johnson, G. D.

2013-12-01

154

Stratigraphic evolution of a Late Triassic to Early Jurassic intracontinental basin in southeastern South China: A consequence of flat-slab subduction?  

NASA Astrophysics Data System (ADS)

An intracontinental basin formed on a young orogen in South China during the Late Triassic to Early Jurassic (T3-J1). A > 2000 m-thick siliciclastic sedimentary succession in the Daxi section, in northern Guangdong Province, near the depocentre of the basin, is correlated with the published Zhuyuan section and three other sections. The combined Daxi-Zhuyuan sections record a marine-influenced deltaic succession of Carnian to Early Toarcian age, spanning a period of ~ 55 Myr. Tectonic controls, rather than eustasy and climate, are interpreted to have played a primary role in the cyclic development of the basin fill. Four regional-scale tectonostratigraphic stages are recognised. Stage 1 features a retrogradation-progradation cycle characterised by increasing then slowly decreasing subsidence rates, accompanied by slow to medium sedimentation rates. Stage 2 is broadly an aggradational cycle with multiple smaller-scale retrogradational-progradational cycles. A complex interplay between moderate subsidence rates, high sedimentation rates and eustasy is interpreted for this stage. Stage 3 represents a retrogradational-aggradational-progradational cycle during which the impact of global sea level was much reduced. This period was characterised by mostly high sedimentation and high subsidence rates, but a change to lower subsidence and sedimentation rates took place prior to the intracontinental uplift that inverted the basin. Stage 4 records continued uplift and the subsequent development of a Late Jurassic-Cretaceous basin-and-range province. The temporal-spatial evolution of the basin could be best explained by the gravitational pull of a subducted flat-slab and its subsequent foundering.

Pang, Chong-Jin; Krapež, Bryan; Li, Zheng-Xiang; Xu, Yi-Gang; Liu, Hai-Quan; Cao, Jun

2014-04-01

155

Jurassic platform development, northwestern Gulf of Mexico  

Microsoft Academic Search

Triassic and Early Jurassic rifting set the stage for the subsequent development of carbonate platforms in the Late Jurassic. These platforms formed along the interior margins of salt basins separated from the main ancestral Gulf of Mexico by a series of positive features. A major sea level rise, after deposition of the Louann Salt (late Callovian), drowned the interior salt

C. H. Jr

1987-01-01

156

Thermal evolution of Tethyan surface waters during the Middle-Late Jurassic: Evidence from ?18O values of marine fish teeth  

NASA Astrophysics Data System (ADS)

Oxygen isotope compositions of phosphate from vertebrate tooth enamel were measured to determine the evolution of tropical sea surface (<˜200 m depth) temperatures in the western Tethys during the Middle-Late Jurassic. On the basis of a high-resolution stratigraphic framework with a 1 Myr time resolution, vertebrate teeth were sampled on Aalenian to Portlandian isochrons over the Anglo-Paris Basin. Asteracanthus sharks and Pycnodontidae teleosteans, identified as sea surface dwellers, have enamel with ?18O values that range from 18.5 to 22.3‰. Thermal variations of tropical surface waters, with amplitudes of a few degrees per few million years, suggest that Middle to Late Jurassic climates were quite variable. Assuming a seawater ?18O value of 0‰ for surface tropical waters in the absence of polar ice caps, temperatures increased from 25 to 29°C from the mid-Bajocian to mid-Bathonian. During the middle to late Bathonian, a strong geographic zonation in isotopic compositions is observed between the eastern and western parts of the basin. High ?18O values of fish tooth enamel (up to 22.3‰) could reflect the arrival of a cold water current from the Arctic during the opening of the North Sea rift. An apparent large drop of temperatures from 28 to 21°C is identified at the Callovian-Oxfordian boundary over no more than ?2-3 Myr. This cooling is compatible with previous paleobotanical and geochemical studies and can be precisely correlated with the migration of boreal ammonites into the Tethyan domain. Because isotopic sea surface temperatures are probably too low to be compatible with tropical climatic conditions, the ?18O value of seawater could have been >0‰ owing to limited growth of continental ice during the early middle Oxfordian. The resulting sea level fall is estimated to be at least 50 m and is compatible with a global regression stage. The middle Oxfordian thermal minimum is followed by a new warming stage of 3-4°C from the middle to the late Oxfordian.

LéCuyer, Christophe; Picard, StéPhanie; Garcia, Jean-Pierre; Sheppard, Simon M. F.; Grandjean, Patricia; Dromart, Gilles

2003-09-01

157

Late Pleistocene fossil find in Svalbard: the oldest remains of a polar bear (Ursus maritimus Phipps, 1744) ever discovered  

E-print Network

(Ursus arctos L., 1758), the American black bear (Ursus americanus Pallas, 1780) and the Asiatic blackLate Pleistocene fossil find in Svalbard: the oldest remains of a polar bear (Ursus maritimus in Svalbard, a well preserved subfossil left mandible of a polar bear (Ursus maritimus Phipps, 1774

Ingólfsson, �lafur

158

Late Early Permian plant fossils from the Canadian High Arctic: a rare paleoenvironmental\\/climatic window in northwest Pangea  

Microsoft Academic Search

Recently discovered megafossil plant remains in late Early Permian (Kungurian) marine sediments on northern Axel Heiberg Island, Canadian Arctic Archipelago, provide a much needed datum point for paleobiogeographic considerations in this part of North America. The fossil plants represent at least ten families belonging to several major groups (sphenopsids, ferns, pteridosperms, ginkgos, cordaitaleans, and conifers). The conifers Rufloria and Walchia

Ben A LePage; Benoit Beauchamp; Hermann W Pfefferkorn; John Utting

2003-01-01

159

Exceptionally well preserved late Quaternary plant and vertebrate fossils from a blue hole on Abaco, The Bahamas.  

PubMed

We report Quaternary vertebrate and plant fossils from Sawmill Sink, a "blue hole" (a water-filled sinkhole) on Great Abaco Island, The Bahamas. The fossils are well preserved because of deposition in anoxic salt water. Vertebrate fossils from peat on the talus cone are radiocarbon-dated from approximately 4,200 to 1,000 cal BP (Late Holocene). The peat produced skeletons of two extinct species (tortoise Chelonoidis undescribed sp. and Caracara Caracara creightoni) and two extant species no longer in The Bahamas (Cuban crocodile, Crocodylus rhombifer; and Cooper's or Gundlach's Hawk, Accipiter cooperii or Accipiter gundlachii). A different, inorganic bone deposit on a limestone ledge in Sawmill Sink is a Late Pleistocene owl roost that features lizards (one species), snakes (three species), birds (25 species), and bats (four species). The owl roost fauna includes Rallus undescribed sp. (extinct; the first Bahamian flightless rail) and four other locally extinct species of birds (Cooper's/Gundlach's Hawk, A. cooperii/gundlachii; flicker Colaptes sp.; Cave Swallow, Petrochelidon fulva; and Eastern Meadowlark, Sturnella magna) and mammals (Bahamian hutia, Geocapromys ingrahami; and a bat, Myotis sp.). The exquisitely preserved fossils from Sawmill Sink suggest a grassy pineland as the dominant plant community on Abaco in the Late Pleistocene, with a heavier component of coppice (tropical dry evergreen forest) in the Late Holocene. Important in its own right, this information also will help biologists and government planners to develop conservation programs in The Bahamas that consider long-term ecological and cultural processes. PMID:18077421

Steadman, David W; Franz, Richard; Morgan, Gary S; Albury, Nancy A; Kakuk, Brian; Broad, Kenneth; Franz, Shelley E; Tinker, Keith; Pateman, Michael P; Lott, Terry A; Jarzen, David M; Dilcher, David L

2007-12-11

160

Late Holocene vegetation and historic grazing impacts at Capital Reef National Park reconstructed using fossil packrat middens  

Microsoft Academic Search

Late Holocene vegetation change from a high desert site in southern Utah was reconstructed using fossil plant macrofossils and pollen from packrat middens. Presettlement middens consistently contained abundant macrofossils of plant species palatable to livestock that are now absent or reduced such as: Ceratoides lanata, Stipa hymenoides, Pinus edulis, and Artemisia spp.. In contrast, species typical of overgrazed range, such

1995-01-01

161

Stratigraphy of the Jurassic system in northern Egypt  

SciTech Connect

A regional synthesis is presented of the stratigraphy of Jurassic strata in Egypt north of 30/degree/N, based on the study of about 80 wells and outcrops from northeastern Egypt. Almost all fossil groups have been investigated for biostratigraphic control. Published work on ammonite faunas from Gebel el Maghara (north Sinai) is integrated with extensive original work on palynofloras (and, to a lesser extent, ostracod/foraminiferal faunas) recovered from marine rocks in the subsurface. The recovery of rich dinocyst assemblages enables the recognition of a ten-fold zonation scheme, largely within the Middle-Late Jurassic sedimentary package. The upper limit of this package is marked by the Cimmerian erosional event; strata younger than Oxfordian are rarely preserved. Only east of 30/degree/E is significant sedimentation known to have occurred immediately prior to the major early Bajocian transgressive event. Thereafter mean sea level rose steadily. The Lower Triassic-Lower Jurassic sedimentary package is poorly understood, largely the result of scanty and ambiguous stratigraphic evidence. However, regional correlations suggest that only very thin earliest Jurassic (Hettangian ) clastic deposition succeeded a sequence of Upper Triassic carbonates and evaporites (Wadi en Natrun Formation) in the north. Arising from these studies is a standard lithostratigraphical scheme. The upper sedimentary package, the Gebel el Maghara Group, comprises three formations (Masajid, Khatatba, and Inmar) and seven members; new units are defined and old units redefined.

Keeley, M.L.; Shaw, D.; Forbes, G.A.

1988-08-01

162

Vitis seeds (Vitaceae) from the late Neogene Gray Fossil Site, northeastern Tennessee, U.S.A  

Microsoft Academic Search

This study focuses on morphometric and systematic analyses of the fossil Vitis seeds, recovered from the Gray Fossil Site (7–4.5Ma, latest Miocene–earliest Pliocene), northeastern Tennessee, U.S.A. A multivariate analysis based on eleven measured characters from 76 complete fossil seeds recognizes three morphotaxa. Further comparisons with both selected modern and fossil vitaceous specimens confirm that these morphotaxa represent three new species,

Fade Gong; Istvan Karsai

2010-01-01

163

Three new Jurassic euharamiyidan species reinforce early divergence of mammals.  

PubMed

The phylogeny of Allotheria, including Multituberculata and Haramiyida, remains unsolved and has generated contentious views on the origin and earliest evolution of mammals. Here we report three new species of a new clade, Euharamiyida, based on six well-preserved fossils from the Jurassic period of China. These fossils reveal many craniodental and postcranial features of euharamiyidans and clarify several ambiguous structures that are currently the topic of debate. Our phylogenetic analyses recognize Euharamiyida as the sister group of Multituberculata, and place Allotheria within the Mammalia. The phylogeny suggests that allotherian mammals evolved from a Late Triassic (approximately 208 million years ago) Haramiyavia-like ancestor and diversified into euharamiyidans and multituberculates with a cosmopolitan distribution, implying homologous acquisition of many craniodental and postcranial features in the two groups. Our findings also favour a Late Triassic origin of mammals in Laurasia and two independent detachment events of the middle ear bones during mammalian evolution. PMID:25209669

Bi, Shundong; Wang, Yuanqing; Guan, Jian; Sheng, Xia; Meng, Jin

2014-10-30

164

The Late Triassic-Early Jurassic volcanism of Morocco and Portugal in the framework of the Central Atlantic Magmatic Province: An overview  

NASA Astrophysics Data System (ADS)

An overview on the Late Triassic-Early Jurassic Magmatic Province of Morocco and Portugal (TJMPMP) is presented. It comprises extrusive basalts, interbedded with clastic rocks sequences preserved in elongated rift basins, and their feeder dikes and sills. Paleontologic ages range from Upper Ladinian-Lower Carnian to the Sinemurian for the sediments, while available 40Ar/39Ar analysis yield a mean age of 200±1,6 Ma for the volcanics. The volcanologic characteristics of the TJMPMP are those of continental basaltic successions. It comprises subaerial lava flows and pyroclastic deposits, sometimes deposited in lacustrine environments, and feeder dikes, constituting an interesting volcanic sub-province of the Central Atlantic Magmatic Province (CAMP) as most preserved outcrops are extrusive volcanics. These rocks correspond to Low-Ti (TiO2<2wt%), quartz normative, tholeiites displaying uniform chemical and isotopic characteristics, and showing variable upper crustal contamination. The most primitive non-contaminated rocks display 87Sr/86Sr ˜0,70553 and Ba / Nb>11 suggesting that their source may be within the continental lithospheric mantle. The nucleation of the rifting process may have started at two different triple junctions, an RRR junction near Florida and a RRT between Africa-Iberia-America.

Youbi, Nasrrddine; Martins, Línia Tavares; Munhá, José Manuel; Ibouh, Hassan; Madeira, José; Aït Chayeb, El Houssaine; El Boukhari, Abdelmajid

165

Alternative models for Late Jurassic and Early Cretaceous paleogeography of the western Cordillera, California to SE Alaska  

Microsoft Academic Search

The Franciscan-Great Valley-Sierran triad is indisputable evidence for late Mesozoic, west-facing subduction along the California sector of the N. American margin. In the northwestern sector (N of 48[degree]N), however, neither the configuration of plate boundaries, nor the paleogeographic disposition of the Insular and Intermontane superterranes, is confidently established. Models divide into two groups. One set, based entirely on geologic evidence

1993-01-01

166

Transtensional tectonics induced by oblique reactivation of previous lithospheric anisotropies during the Late Triassic to Early Jurassic rifting in the Neuquén basin: Insights from analog models  

NASA Astrophysics Data System (ADS)

The goal of this study was to determine the main factors that controlled the kinematic evolution and the structural architecture developed during the Late Triassic to Early Jurassic rifting that led to the opening of the Neuquén basin in the southwestern sector of Gondwana. We carried out a series of analog models to simulate an extensional system with a bent geometry similar to the northeastern border of the basin. In different experiments, we varied the extension direction between NNE (N10°E) and NE (N45°E) orientations, inducing rift systems with different degrees of obliquity in each sector of the extended area. We compared the kinematic evolution and the final structural architecture observed in the experiments with data from two selected representative areas of the basin: (1) the Atuel depocenter, situated in the northern Andean sector, and (2) the Entre Lomas area, situated in the northeastern Neuquén Embayment. In both cases, the good match between the field and subsurface data and the results of the analog models supports a NNE orientation of the regional extension (N30°E-N20°E) during the synrift stage. Our experimental results suggest that lithospheric weakness zones of NNW to NW trend could have controlled and localized the extension in the Neuquén basin. These previous anisotropies were linked to the sutures and rheological contrasts generated during the collision of terranes against the southwestern margin of Gondwana during the Paleozoic, as well as further modifications of the thermo-mechanical state of the lithosphere during the Late Paleozoic to Early Mesozoic evolution.

Bechis, Florencia; Cristallini, Ernesto O.; Giambiagi, Laura B.; Yagupsky, Daniel L.; Guzmán, Cecilia G.; García, Víctor H.

2014-09-01

167

First record of a Jurassic mammal (?"Peramura") from Ethiopia  

E-print Network

First record of a Jurassic mammal (?"Peramura") from Ethiopia WILLIAM A. CLEMENS, MARK B. GOODWIN, M.B., Hutchison, J.H., Schaff, C.R., Wood, C.B., and Colbert, M.W. 2007. First record of a Jurassic of estuarine to fluvial deposits that are thought to be of Late Jurassic (Tithonian) age. The fragment

Goodwin, Mark B.

168

ACCEPTED MANUSCRIPT Impact of basin burial and exhumation on Jurassic  

E-print Network

M ANUSCRIPT ACCEPTED ACCEPTED MANUSCRIPT Impact of basin burial and exhumation on Jurassic Several diagenetic models have been proposed for Middle and Upper Jurassic carbonates of the eastern Paris for the Middle and Late Jurassic deposits as a whole. Petrographic (optical and cathodoluminescence microscopy

Paris-Sud XI, Université de

169

CRANIAL ANATOMY, TAXONOMIC IMPLICATIONS AND PALAEOPATHOLOGY OF AN UPPER JURASSIC  

E-print Network

CRANIAL ANATOMY, TAXONOMIC IMPLICATIONS AND PALAEOPATHOLOGY OF AN UPPER JURASSIC PLIOSAUR (REPTILIA marine reptiles of the Late Jurassic are rare, and so the discovery of the 1.8-m- long skull, Kimmeridge Clay, Upper Jurassic, palaeopathology. P liosaurus is an enigmatic, advanced sauroptery- gian

Benton, Michael

170

ISOPOD TRACKWAYS FROM THE CRAYSSAC LAGERSTA TTE, UPPER JURASSIC, FRANCE  

E-print Network

ISOPOD TRACKWAYS FROM THE CRAYSSAC LAGERSTA¨ TTE, UPPER JURASSIC, FRANCE by CHRISTIAN GAILLARD, which occurs abundantly in Late Jurassic deposits of England and France, was probably the trace-maker. Key words: trackways, isopods, intertidal, Tithonian, south- west France. The Upper Jurassic Crayssac

Paris-Sud XI, Université de

171

Late Paleocene fossils from the Cerrejon Formation, Colombia, are the earliest record of Neotropical rainforest  

Microsoft Academic Search

Neotropical rainforests have a very poor fossil record, making hypotheses concerning their origins difficult to evaluate. Never- theless, some of their most important characteristics can be pre- served in the fossil record: high plant diversity, dominance by a distinctive combination of angiosperm families, a preponderance of plant species with large, smooth-margined leaves, and evidence for a high diversity of herbivorous

S. L. Wing; Fabiany Herrera; C. A. Jaramillo; Carolina Gomez-Navarro; P. Wilf; Conrad C. Labandeira

2009-01-01

172

Mass extinctions in the fossil record of late Palaeozoic and Mesozoic tetrapods  

Microsoft Academic Search

The fossil record of tetrapods is very patchy because of the problems of preservation in terrestrial sediments, and because vertebrates are rarely very abundant. However, the fossil record of tetrapods has the advantages that it is easier to establish a phylogenetic taxonomy than for many invertebrate groups (many characters; fast evolution), and there is the potential for more detailed ecological

Michael J. Benton

1990-01-01

173

Mass extinctions in the fossil record of late Palaeozoic and Mesozoic tetrapods  

Microsoft Academic Search

The fossil record of tetrapods is very patchy because of the problems of preservation in terrestrial sediments, and because vertebrates are rarely very abundant. However, the fossil record of tetrapods has the advantages that it is easier to establish a phylogenetic taxonomy than for many invertebrate groups (many characters; ‘fast’ evolution), and there is the potential for more detailed ecological

Michael Benton

174

Late Jurassic to Early Cretaceous transpression, Pine Nut and Luning-Fencemaker fault system, west-central Nevada  

SciTech Connect

Recent studies of the Mesozoic tectonic evolution of the western U.S. Cordillera have called for substantial transcurrent displacement between the Sierra Nevada and the western Great Basin. The location, timing, and sense of shear of the postulated transcurrent fault system(s) are controversial, and to a larger degree the controversy has centered on the Pine Nut fault (PNF) of western Nevada. The northwest-trending Pine Nut fault juxtaposes two coeval assemblages of the Mesozoic marine province of the northwestern Great Basin that have distinctly different structural histories. On the east, Mesozoic rocks are deformed in the late Mesozoic Luning-Fencemaker fold and thrust belt (LFT). To the west, coeval rocks are not involved in structures of the LFT but rather share a structural history with the eastern Sierra Nevada. A segment of the PNF is expressed as a brittle shear zone, up to 3 km wide, mapped discontinuously for over 50 km in the eastern Wassuk Range in west-central Nevada. Cataclasites of the brittle fault zone are superposed on ductility deformed lower Mesozoic layered and intrusive rocks with structures indicating top to the east shear. The ductile deformation, which predated post-kinematic plutons dated by U-Pb as 169 Ma, was accompanied by metamorphism ranging from lower greenschist to amphibolite-facies conditions. The PNF and LFT formed during sinistral transpression and represent components of oblique plate-convergence along the late Mesozoic Sierran are system.

Oldow, J.S. (Rice Univ., Houston, TX (United States). Dept. of Geology and Geophysics)

1993-04-01

175

Crust/mantle interaction during the construction of an extensional magmatic dome: Middle to Late Jurassic plutonic complex from western Liaoning, North China Craton  

NASA Astrophysics Data System (ADS)

Differentiating magmatic doming and low-angle normal faulting remains critical for fully understanding the thermal, mechanical and chemical evolution of continental landmasses under extension. This zircon U-Pb dating and geochemical study documents two Middle to Late Jurassic batholiths (Lüshan and Haitangshan) from the Yiwulüshan range of western Liaoning, North China Craton. They consist of a variety of lithologies including gabbro, diorite, granodiorite, monzogranite, together with microgranular magmatic enclaves (MME) and mafic dykes. Synthesizing petrologic, elemental, whole-rock Sr-Nd and zircon Hf isotopic data leads to the characterization of multiple mafic and felsic end-members and their concomitant interaction in building the magmatic dome. A subduction-related metasomatized lithospheric mantle source is fingerprinted by the gabbroic to dioritic rocks with enriched large ion lithophile elements, depleted high field strength elements and heterogeneous isotopic compositions (87Sr/86Sri = 0.70541 to 0.70577, ?Nd(t) = - 1.78 to - 5.54 and zircon ?Hf(t) = - 6.0 to 8.1). One felsic magma end-member of ancient mafic lower crustal parentage is discernable from adakitic granites with high Sr/Y and evolved isotopic composition (87Sr/86Sri = 0.70533 to 0.70792, ?Nd(t) = - 18.8 to - 21.7, zircon ?Hf(t) = - 18.5 to - 28.8), whereas another felsic magma end-member of newly underplated crustal heritage manifests itself from some monzogranites with non-adakitic elemental affinity and juvenile isotopic composition (87Sr/86Sri = 0.70429 to 0.70587, ?Nd(t) = - 4.47 to - 5.87, zircon ?Hf(t) = 4.3 to 1.3). Hybridization processes between mantle-derived mafic magma and ancient crustal-derived felsic magma result in the formation of MME-bearing granodiorites with intermediate isotopic signatures (87Sr/86Sri = 0.70491 to 0.70499, ?Nd(t) = - 15.3 to - 15.8, zircon ?Hf(t) = - 12.7 to - 17.4). Subsequent fractional crystallization of the hybridized magmas endows the differentiated monzogranites with low Sr/Y and highly evolved isotopes (87Sr/86Sri = 0.70496 to 0.70605, ?Nd(t) = - 16.0 to - 18.7, zircon ?Hf(t) = - 14.3 to - 21.5). Apart from distinguishing Middle-Late Jurassic extensional magmatic doming from Early Cretaceous detachment faulting, this complex mafic-felsic magma association encapsulates a multi-level crust/mantle interaction leading to lithospheric thinning and concomitant crustal architectural reorganization in the Yanshan belt during the Late Mesozoic. Near-synchronization of a two-stage extensional pattern in the Yanshan belt and even across NE continental Asia accords well with gravitational collapse and convective removal of lithospheric mantle within an evolved post-collisional to within-plate extensional regime.

Zhang, Xiaohui; Yuan, Lingling; Wilde, Simon A.

2014-09-01

176

Functional anatomy and feeding biomechanics of a giant Upper Jurassic pliosaur (Reptilia: Sauropterygia)  

E-print Network

Functional anatomy and feeding biomechanics of a giant Upper Jurassic pliosaur (Reptilia. In the Kimmeridgian ecosystem, we conclude that Late Jurassic pliosaurs were generalist predators at the top- zoic from the Late Triassic to Late Cretaceous, some 150 Myr. Towards the end of the Early Jurassic

Benton, Michael

177

Late Tertiary paleoclimatic interpretation from lacustrine rhythmites in the Gray Fossil Site, northeastern Tennessee, USA  

Microsoft Academic Search

The Gray Fossil Site (GFS) includes a small (<2 ha) paleosinkhole lake fill with an exceptionally well-preserved record of\\u000a sedimentation and fossils from the latest Miocene to earliest Pliocene. The uppermost lacustrine stratigraphy is characterized\\u000a by rhythmites that regularly alternate between coarse-grained and organic-rich (A) laminae and fine-grained, silty clay (B)\\u000a laminae. Both the A and B components are almost exclusively

Aaron J. Shunk; Steven G. Driese; John A. Dunbar

2009-01-01

178

Dinoflagellates near the Cretaceous Jurassic Boundary  

Microsoft Academic Search

MANY well-preserved dinoflagellate fossils occur in Jurassic and Cretaceous marine sedimentary sections of various lithologic characteristics in the western North Atlantic and the western side of the Sacramento Valley of California1,2. We have discovered five species which are common to the two sections-las first noticed by W. R. Evitt-each occurring in the Cretaceous above the Cretaceous\\/Jurassic boundary, and not in

D. Habib; J. S. WARREN

1973-01-01

179

Two new species of Archaeohelorus (Hymenoptera, Proctotrupoidea, Heloridae) from the Middle Jurassic of China.  

PubMed

Two new fossil species, Archaeohelorus polyneurus sp. n. and A. tensus sp. n., assigned to the genus Archaeohelorus Shih, Feng & Ren, 2011 of Heloridae (Hymenoptera), are reported from the late Middle Jurassic, Jiulongshan Formation of Inner Mongolia, China. Based on the well-preserved forewings and hind wings of these specimens, the diagnosis of the Archaeohelorus is emended: forewing 2cu-a intersecting Cu and Rs+M at the same point or postfurcal, and hind wing may have tubular veins C, Sc+R, R, Rs, M+Cu, M and Cu distinct, or simplified venation. The new findings also elucidate the evolutionary trend of forewing and hind wing venation and body size for the Heloridae from the late Middle Jurassic to now. PMID:24478588

Shi, Xiaoqing; Zhao, Yunyun; Shih, Chungkun; Ren, Dong

2014-01-01

180

Palaeogeography and relative sea-level history forcing eco-sedimentary contexts in Late Jurassic epicontinental shelves (Prebetic Zone, Betic Cordillera): An ecostratigraphic approach  

NASA Astrophysics Data System (ADS)

The analysis of macroinvertebrate and foraminiferal assemblages from Upper Jurassic (Middle Oxfordian to Lower Kimmeridgian) epicontinental shelf deposits in the Prebetic (Betic Cordillera, southern Spain) reveals the influence of environmental changes. They are expressed as selected parameters in palaeogeographic and stratigraphic trends (litho- and microfacies, faunal composition, taphonomy), which are interpreted in the context of relative sea-level histories. Middle Oxfordian to early Kimmeridgian (Transversarium to Planula Chrones) rocks and faunal assemblages in comparatively distal sectors (distal shelf) show lower sedimentation rates (lumpy lithofacies), and higher proportions of ammonoids, planktic foraminifera, corrasion degree, microboring and encrustation. Landwards, towards the mid-shelf, eco-sedimentary conditions resulted in spongiolithic limestones and marl-limestone rhythmites with local development of microbial-sponge buildups. Greater distance from shore during relative sea-level highs accords with greater: (1) stratigraphic condensation; (2) abundance in ammonoids, planktic foraminifera and nubeculariids; and (3) degrees of corrasion, microboring and encrustation. These trends in faunal composition and taphonomy agree with backstepping phases, increasing ecospace and a longer exposition of shelly remains on the sea bottom. Decreasing distance from shore during relative sea-level lows relates to opposite trends, as evidenced by: (4) increasing terrigenous input and decreasing stratigraphic condensation; (5) impoverishment in ammonoids and planktic foraminifera; and (6) diminution of corrasion, microboring and encrustation. Phases of forestepping/progradation and aggradation, a reduction of ecospace for nekto-planktic organisms, and comparatively rapid burial of shell remains are interpreted to force the recorded trends. An ecostratigraphic approach is used here to correlate and characterise sea-level changes, applying high resolution stratigraphy to sections where the identification of relevant surfaces is more difficult. The changes in distance from shore and ecospace, triggered by relative sea-level fluctuations, are considered prime factors forcing trade-offs in faunal communities of the studied fossil assemblages. Ecostratigraphy was used as a template for the characterization, correlation and interpretation of relative sea-levels and associated sedimentary packages in a time span from just above the Milankovitch band to the million-year scale.

Olóriz, Federico; Reolid, Matías; Rodríguez-Tovar, Francisco J.

2012-02-01

181

First glimpse into Lower Jurassic deep-sea biodiversity: in situ diversification and resilience against extinction.  

PubMed

Owing to the assumed lack of deep-sea macrofossils older than the Late Cretaceous, very little is known about the geological history of deep-sea communities, and most inference-based hypotheses argue for repeated recolonizations of the deep sea from shelf habitats following major palaeoceanographic perturbations. We present a fossil deep-sea assemblage of echinoderms, gastropods, brachiopods and ostracods, from the Early Jurassic of the Glasenbach Gorge, Austria, which includes the oldest known representatives of a number of extant deep-sea groups, and thus implies that in situ diversification, in contrast to immigration from shelf habitats, played a much greater role in shaping modern deep-sea biodiversity than previously thought. A comparison with coeval shelf assemblages reveals that, at least in some of the analysed groups, significantly more extant families/superfamilies have endured in the deep sea since the Early Jurassic than in the shelf seas, which suggests that deep-sea biota are more resilient against extinction than shallow-water ones. In addition, a number of extant deep-sea families/superfamilies found in the Glasenbach assemblage lack post-Jurassic shelf occurrences, implying that if there was a complete extinction of the deep-sea fauna followed by replacement from the shelf, it must have happened before the Late Jurassic. PMID:24850917

Thuy, Ben; Kiel, Steffen; Dulai, Alfréd; Gale, Andy S; Kroh, Andreas; Lord, Alan R; Numberger-Thuy, Lea D; Stöhr, Sabine; Wisshak, Max

2014-07-01

182

Trace fossils on a Late Ordovician glacially striated pavement in Algeria  

Microsoft Academic Search

An exceptional exposure of Late Ordovician glaciogenic sediments crops out in Dider, SE Algeria, within the Tassili N'Ajjer region. The sediments consist of sandstones and diamictites sandwiched between a Mid Ordovician fluvial and tidal sandstone (In Tahouite Formation) below and Early Silurian shale (Oued Imirhou Formation) above. Stratigraphic discontinuities within the Late Ordovician glaciogene succession include palaeovalley incisions and glacially

Daniel Paul Le Heron

2010-01-01

183

Late Ordovician (Hirnantian) shelly fossils from New Zealand and their significance  

Microsoft Academic Search

A poorly preserved fauna of brachiopods, trilobites, corals, molluscs, bryozoans, echinoderms, and ostracods is described from Wangapeka Valley, northwest South Island. It can be dated to the latest Ordovician Hirnantian Stage, equivalent to Bolindian Bo4?Bo5, by immediately underlying graptolite faunas and also by some of its contained shelly fossils. It is one of only two shelly faunas of Middle or

L. R. M. Cocks; Roger A. Cooper

2004-01-01

184

Possible animal body fossils from the Late Neoproterozoic interglacial successions in the Kimberley region, northwestern Australia  

Microsoft Academic Search

New specimens of the enigmatic Ediacara-type fossil Palaeopascichnus have been identified from the upper part of the Neoproterozoic Ranford Formation in the Kimberley region, northwest Australia. New material is morphologically similar to Palaeopascichnus and represents the largest species of this genus. They resemble the present-day xenophyophore protists in chamber morphology and growth patterns, supporting the interpretation that Palaeopascichnus is possibly

Zhong-Wu Lan; Zhong-Qiang Chen

185

Fossil proxies of near-shore sea surface temperatures and seasonality from the late Neogene Antarctic shelf  

NASA Astrophysics Data System (ADS)

We evaluate the available palaeontological and geochemical proxy data from bivalves, bryozoans, silicoflagellates, diatoms and cetaceans for sea surface temperature (SST) regimes around the nearshore Antarctic coast during the late Neogene. These fossils can be found in a number of shallow marine sedimentary settings from three regions of the Antarctic continent, the northern Antarctic Peninsula, the Prydz Bay region and the western Ross Sea. Many of the proxies suggest maximum spring-summer SSTs that are warmer than present by up to 5 °C, which would result in reduced seasonal sea ice. The evidence suggests that the summers on the Antarctic shelf during the late Neogene experienced most of the warming, while winter SSTs were little changed from present. Feedbacks from changes in summer sea ice cover may have driven much of the late Neogene ocean warming seen in stratigraphic records. Synthesized late Neogene and earliest Quaternary Antarctic shelf proxy data are compared to the multi-model SST estimates of the Pliocene Model Intercomparison Project (PlioMIP) Experiment 2. Despite the fragmentary geographical and temporal context for the SST data, comparisons between the SST warming in each of the three regions represented in the marine palaeontological record of the Antarctic shelf and the PlioMIP climate simulations show a good concordance.

Clark, Nicola A.; Williams, Mark; Hill, Daniel J.; Quilty, Patrick G.; Smellie, John L.; Zalasiewicz, Jan; Leng, Melanie J.; Ellis, Michael A.

2013-08-01

186

Fossil proxies of near-shore sea surface temperatures and seasonality from the late Neogene Antarctic shelf.  

PubMed

We evaluate the available palaeontological and geochemical proxy data from bivalves, bryozoans, silicoflagellates, diatoms and cetaceans for sea surface temperature (SST) regimes around the nearshore Antarctic coast during the late Neogene. These fossils can be found in a number of shallow marine sedimentary settings from three regions of the Antarctic continent, the northern Antarctic Peninsula, the Prydz Bay region and the western Ross Sea. Many of the proxies suggest maximum spring-summer SSTs that are warmer than present by up to 5 °C, which would result in reduced seasonal sea ice. The evidence suggests that the summers on the Antarctic shelf during the late Neogene experienced most of the warming, while winter SSTs were little changed from present. Feedbacks from changes in summer sea ice cover may have driven much of the late Neogene ocean warming seen in stratigraphic records. Synthesized late Neogene and earliest Quaternary Antarctic shelf proxy data are compared to the multi-model SST estimates of the Pliocene Model Intercomparison Project (PlioMIP) Experiment 2. Despite the fragmentary geographical and temporal context for the SST data, comparisons between the SST warming in each of the three regions represented in the marine palaeontological record of the Antarctic shelf and the PlioMIP climate simulations show a good concordance. PMID:23828612

Clark, Nicola A; Williams, Mark; Hill, Daniel J; Quilty, Patrick G; Smellie, John L; Zalasiewicz, Jan; Leng, Melanie J; Ellis, Michael A

2013-08-01

187

Vertebrate fossils from the Adamantina Formation (Late Cretaceous), Prata Paleontological District, Minas Gerais State, Brazil  

Microsoft Academic Search

In this contribution is given a preliminary up-to-date annotated list of all fossil vertebrates from the Turonian–Santonian Adamantina Formation, Bauru Group where it occurs in the Prata Paleontological District which is located 45 km to the west of Prata in Minas Gerais State, Brazil. The Adamantina Formation is reddish sandstone in the Triângulo Mineiro region. These fluviolacustrine sediments were deposited in

Carlos Roberto A. Candeiro; Adriano R. Santos; Thomas H. Rich; Thiago S. Marinho; Emerson C. Oliveira

188

Vertebrate fossils from the Adamantina Formation (Late Cretaceous), Prata paleontological district, Minas Gerais State, Brazil  

Microsoft Academic Search

In this contribution is given a preliminary up-to-date annotated list of all fossil vertebrates from the Turonian–Santonian Adamantina Formation, Bauru Group where it occurs in the Prata paleontological district which is located 45 km to the west of Prata in Minas Gerais State, Brazil. The Adamantina Formation is a reddish sandstone in the Triângulo Mineiro region. These fluviolacustrine sediments were deposited

Carlos Roberto A. Candeiro; Adriano R. Santos; Thomas H. Rich; Thiago S. Marinho; Emerson C. Oliveira

2006-01-01

189

A new fossil thryonomyid from the Late Miocene of the United Arab Emirates and the origin of African cane rats.  

PubMed

Cane rats (Thryonomyidae) are represented today by two species inhabiting sub-Saharan Africa. Their fossil record is predominately African, but includes several Miocene species from Arabia and continental Asia that represent dispersal events from Africa. For example, Paraulacodus indicus, known from the Miocene of Pakistan, is closely related to living Thryonomys. Here we describe a new thryonomyid, Protohummus dango, gen. et sp. nov., from the late Miocene Baynunah Formation of the United Arab Emirates. The new thryonomyid is less derived than "Thryonomys" asakomae from the latest Miocene of Ethiopia and clarifies the origin of crown Thryonomys and the evolutionary transition from Paraulacodus. A phylogenetic analysis shows Protohummus dango to be morphologically intermediate between Paraulacodus spp. and extinct and living Thryonomys spp. The morphological grade and phylogenetic position of Protohummus dango further supports previous biochronological estimates of the age of the Baynunah Formation (ca. 6-8 Ma). PMID:23625517

Kraatz, Brian P; Bibi, Faysal; Hill, Andrew; Beech, Mark

2013-05-01

190

Late Holocene vegetation and historic grazing impacts at Capital Reef National Park reconstructed using fossil packrat middens  

SciTech Connect

Late Holocene vegetation change from a high desert site in southern Utah was reconstructed using fossil plant macrofossils and pollen from packrat middens. Presettlement middens consistently contained abundant macrofossils of plant species palatable to livestock that are now absent or reduced such as: Ceratoides lanata, Stipa hymenoides, Pinus edulis, and Artemisia spp.. In contrast, species typical of overgrazed range, such as: Chrysothamnus visidiflorus, Sarcobatus vermiculatus, and Gutterezia sarothrae, are now more abundant than prior to the historic introduction of grazing animals. Similar changes are evident in the fossil pollen from the packrat middens. Pine and sagebrush pollen is now far lower than prior to settlement, while Salsola sp. is first recorded following settlement. Ordination of the plant records using Detrended Correspondence Analysis demonstrates that the modem assemblages are substantially different from the presettlement assemblages and that the rates of vegetation change accompanying settlement are far greater than any recorded during the previous 5000 years. These results suggest that the plant communities and rates of vegetation change observed during this century are unlike previous natural communities and rates of vegetation change.

Cole, K.L. [Univ. of Minnesota, St. Paul, MN (United States)

1995-06-01

191

Schweickert, R. A.; and Merguerian, Charles, 1980, Augen gneiss in the Shoo Fly Complex, Tuolumne County, California -a pre-Middle Jurassic plutonic episode.  

E-print Network

County, California - a pre-Middle Jurassic plutonic episode. An ancient, deformed plutonic suite-mid Jurassic east-plunging, E-W trending fold system (F4), and intruded by Late Jurassic mafic dikes. Isotropic Jurassic-Late Cretaceous SNB is essentially undefined at present. To Cite This Abstract: Schweickert, R. A

Merguerian, Charles

192

New data on Late Vendian problematic fossils from the genus Harlaniella  

NASA Astrophysics Data System (ADS)

The morphology and stratigraphic distribution of Harlaniella podolica Sokolov, 1972 and H. ingriana Ivantsov, sp. nov. were investigated using the collection of impressions sampled recently in Upper Vendian sections of Russia (southeastern White Sea region) and Ukraine (Podoliya). These fossils, which were previously considered as representing coprolites or grazing or locomotion traces, are interpreted as internal casts and impressions of fragments of tubes of initially organic composition. Streptichnus narbonnei Jensen et Runnegar, 2005 from Vendian-Cambrian boundary strata of Namibia are also attributed to this group. It is assumed that the tubes are similar to remains of the algal genera Vendotaenia Gnilovskaya, 1971 from Vendian deposits of the East European Platform and Liulingjitaenia Chen et Xiao, 1992 from Sinian sections of China.

Ivantsov, A. Yu.

2013-11-01

193

Dinosaur dynamics in the Jurassic Era  

NASA Astrophysics Data System (ADS)

Dinosaurs were fascinating animals and elicit much excitement in the classroom. Analysis of fossilized dinosaur trackways permits one to estimate the locomotion speeds and accelerations of these extinct beasts. Such analysis allows one to apply Newton's laws of motion to examples from the Jurassic Era.

Lee, Scott

2010-04-01

194

The origin of Jurassic reefs: Current research developments and results  

Microsoft Academic Search

Summary  In order to elucidate the control of local, regional and global factors on occurrence, distribution and character of Jurassic\\u000a reefs, reefal settings of Mid and Late Jurassic age from southwestern Germany, Iberia and Romania were compared in terms of\\u000a their sedimentological (including diagenetic), palaeoecological, architectural, stratigraphic and sequential aspects. Upper\\u000a Jurassic reefs of southern Germany are dominated by siliceous sponge—microbial

Reinhold R. Leinfelder; Manfred Krautter; Ralf Laternser; Martin Nose; Dieter U. Schmid; Günter Schweigert; Winfried Werner; Helmut Keupp; Hartmut Brugger; Regina Herrmann; Ursula Rehfeld-Kiefer; Johannes H. Schroeder; Carsten Reinhold; Roman Koch; Arnold Zeiss; Volker Schweizer; Heinrich Christmann; Götz Menges; Hanspeter Luterbacher

1994-01-01

195

Late-Holocene fossil rodent middens from the Arica region of northernmost Chile  

USGS Publications Warehouse

Identification of >40 taxa of plant macrofossils in 14 rodent (Abrocoma) middens collected from 2800 to 3590 m elevation at the latitude of Arica, Chile (18??S) provide snapshots of vegetation in the northernmost Atacama Desert over the past 3000 years. Midden floras show considerable stability throughout the late Holocene, which may be due in part to the broad elevational ranges of many perennial species and midden insensitivity to changes in plant community structure. The greatest variability is found in annuals in the Prepuna, a climatically sensitive zone. This variability, however might also arise from the brevity of midden depositional episodes. As the first midden record from the Arica-Parinacota Region (Chile's northernmost administrative region), this study demonstrates the potential for future midden research in this area. ?? 2007 Elsevier Ltd. All rights reserved.

Holmgren, C.A.; Rosello, E.; Latorre, C.; Betancourt, J.L.

2008-01-01

196

Late-Holocene fossil rodent middens from the Arica region of northernmost Chile  

USGS Publications Warehouse

Identification of >40 taxa of plant macrofossils in 14 rodent (Abrocoma) middens collected from 2800 to 3590 m elevation at the latitude of Arica, Chile (18°S) provide snapshots of vegetation in the northernmost Atacama Desert over the past 3000 years. Midden floras show considerable stability throughout the late Holocene, which may be due in part to the broad elevational ranges of many perennial species and midden insensitivity to changes in plant community structure. The greatest variability is found in annuals in the Prepuna, a climatically sensitive zone. This variability, however might also arise from the brevity of midden depositional episodes. As the first midden record from the Arica-Parinacota Region (Chile's northernmost administrative region), this study demonstrates the potential for future midden research in this area.

Holmgren, C.A.; Rosello, E.; Latorre, C.; Betancourt, J.L.

2008-01-01

197

2D Geochemical Characterisation of Late Carboniferous Concretions: Constraints for 3D Fossil Preservation  

NASA Astrophysics Data System (ADS)

Because of their potential to perfectly preserve fossils in three dimensions, concretions and nodules from various stratigraphic positions and different geological settings have been the subject of intense investigations in the past. The results of these studies aided to elucidate the fine- and ultrastructure of fossilised materials, and gave detailed insights into the anatomy of many plants and animals of the geological past. Nodules have been described as concretionary bodies which are formed by the precipitation of authigenic minerals. They are sometimes monomineralic and homogenous, but polymineralic nodules are characterised by concentric zones of different mineralogical compositions (such as chert, barite, phosphates or manganiferous ores) around a mostly biogenic core. Several factors have been recognised which are thought to play an important role for the formation of nodules. These include [1] the availability of nucleating materials, [2] presence of metals in the water column and sediment, [3] favourable tectonic and physiographic features, [4] favourable sediment-water interface, [5] low rate of sedimentation, [6] presence of nutrient rich bottom water mass and [7] an oxidizing/reducing environment. Up to now, no consistent generic model has been proposed to address the complex geochemical interactions between these factors in the course of nodule formation. With the aim, to describe the different geochemical reactions that lead to nodule generation and hence fossil preservation, a ferromanganese nodule was extracted from the Upper Carboniferous sequences at Broadhaven, Pembrokshire, UK. The geology of this area consists of cyclothems, which contain cyclic sequences of limestones, sandstones and shales. Within this sequence, the nodules are located in the shale beds. The extracted ferromanganese nodule was cut in half using a diamond rock saw and is 7.1 cm in height and 9.8 cm in width. For the analysis of major and trace elements a Niton XL3t X-ray fluorescence instrument was used. A grid of 3mm by 3mm was then drawn onto the cut surface of the nodule in graphite pencil. A graphite pencil was chosen as graphite (Carbon) is too light to interfere with the incident x-ray beam of the XRF. A total of 1052 data points produced by this grid formed the points at which the XRF analysis was undertaken. Elements analysed were Ag, Al, As, Ba, Ca, Cl, Cd, Cr, Cs, Cu, Fe, Hg, K, Mn, Nb, Ni, P, Pd, Rb, S, Sb, Sc, Se, Si, Sn, Sr, Te, Th, Ti, U, V, Zn and Zr. This geochemical data has been modelled into 2D contour maps and 3D elevation models which have shown significant and systematic enrichments (Ag, As, Ba, Ca, Cd, Cr, Cs, Fe, Hg, Mn, Ni, P, S, Sb, Si, Sn, Sr, Te, Th, U, V, Zn) and depletions (Al, Cl, Cu, K, Nb, Pd, Rb, Sc, Se, Ti, Zr) of elements across the extent of the nodule. The geochemical data obtained were used to establish the types of geochemical reduction/oxidation-reactions that were involved during the formation of the nodule. A new model, based on non-linear disequilibrium quasi-Belousov-Zhabotinsky reactions, for nodule formation is presented and will be discussed.

Howell, C. P.; Montenari, M.

2012-04-01

198

Identification of organic matter sources in sulfidic late Holocene Antarctic fjord sediments from fossil rDNA sequence analysis  

NASA Astrophysics Data System (ADS)

The 18S ribosomal DNA (rDNA) isolated from sulfidic Holocene sediments and particulate organic matter in the water column of the stratified Small Meromictic Basin (SMB) in Ellis Fjord (eastern Antarctica) was analyzed to identify possible biological sources of organic matter. Previous work had shown that the sediments contained numerous diatom frustules and high contents of a highly branched isoprenoid (HBI) C25:2 alkene (which is a specific biomarker of certain species of the diatom genera Navicula, Haslea, Pleurosigma, or Rhizosolenia), so we focused our search on preserved fossil 18S rDNA of diatoms using sensitive polymerase chain reaction (PCR) approaches. We did not find diatom-derived fossil 18S rDNA using general eukaryotic primers, and even when we used primers selective for diatom 18S rDNA, we only identified a Chaetoceros phylotype, which is known to form cysts in the SMB but is not a likely source of the C25:2 HBI. When we used PCR/denaturing gradient gel electrophoresis methods specific to phylotypes within the HBI-biosynthesizing genera, we were able to identify three phylotypes in the sediments related to HBI-producing strains of the genera Haslea and Navicula. The ancient DNA data thus provided a limited, but valuable, view of the diversity of late Holocene primary producers with a particular bias to specific components of the biota that were better preserved such as the Chaetoceros cysts. This use of paleogenetics also revealed unexpected possible sources of organic matter such as novel stramenopiles for which no specific lipid biomarkers are known and thus would not have been identified based on traditional lipid stratigraphy alone.

Coolen, Marco J. L.; Volkman, John K.; Abbas, Ben; Muyzer, Gerard; Schouten, Stefan; Sinninghe Damsté, Jaap S.

2007-06-01

199

The Terrestrial Fossil Organic Matter Record of Global Carbon Cycling: A Late Paleozoic through Early Mesozoic Perspective  

NASA Astrophysics Data System (ADS)

The carbon isotope composition of terrestrial fossil organic matter (?13Corg) has been widely used as a proxy of global carbon cycling and to reconstruct perturbations to the ocean-atmosphere carbon budget. The degree to which terrestrial ?13Corg records local to regional environmental conditions versus the evolution of the global carbon cycle has been highly debated. The high-resolution (104 to 106 m.y.) terrestrial ?13Corg record presented here defines a long-term trend through the latest Devonian to Late Triassic that reveals significant and systematic variations that track independently inferred changes in climate, paleo-atmospheric pCO2, and major restructuring in paleotropical flora. This newly derived record is based on 350 carbon isotope analyses of compressed and permineralized plants, cuticle, charcoal and coal (including vitrinite and fusinite) collected from paleo-wetland mudstones and claystones, claystone-filled abandoned fluvial channels, floodplain mudstones, and ephemeral lacustrine deposits at paleo-tropical to paleo-temperate latitudes. Morphologic and geochemical analysis of contemporaneous paleosols and fluvial-alluvial deposits allow for correlation of terrestrial ?13Corg values to reconstructed paleo-environmental conditions. Terrestrial ?13Corg values of contemporaneous fossil organic matter exhibit systematic inter- and intra-basinal variation of up to 2‰ associated with differences in paleo-precipitation and burial history, and geomorphic position within depositional basins and paleo-fluvial systems. Variation in ?13Corg by organic matter type is minimal to less than 1.5‰; specifically, charcoal ?13Corg values overlap to are slightly less negative than those of thermally less mature organic components analyzed. Overall, variation within contemporaneous populations is significantly less than defined by the long-term terrestrial ?13Corg record. Moreover, paleo-floral pi/pa ratios, an established proxy of water-use efficiency of plant growth, estimated from measured terrestrial ?13Corg values and contemporaneous marine carbonate ?13C values define a relatively consistent and narrow range (0.45 to 0.6) throughout the 150 million year interval within each depositional basin, regardless of landscape or stratigraphic position. Their narrow range in conjunction with the statistically significant long-term ?13Corg trend indicates that local to regional environmental effects on ?13Corg were secondary to extrabasinal influences such as the carbon isotopic composition of the paleo-atmosphere. This suggests that the long-term terrestrial ?13Corgrecord archives first-order variations in atmospheric ?13C throughout the Late Paleozoic and Early Mesozoic.

Montanez, I. P.

2006-12-01

200

Middle and upper jurassic depositional environments at outer shelf and slope of Baltimore Canyon Trough  

Microsoft Academic Search

New CDP data acquired in the Baltimore Canyon Trough during project LASE made it possible to map a continuous Jurassic sedimentary sequence from the continental margin to the abyssal plain without interruption by basement structures. Intense carbonate sedimentation is inferred at the outer shelf during the Middle and Late Jurassic. Carbonate sedimentation probably started during the Middle Jurassic with a

L. A. Gamboa; P. L. Stoffa; M. Truchan

1985-01-01

201

Geological Society of America Paleogeographic and tectonic implications of Jurassic sedimentary  

E-print Network

of Jurassic sedimentary and volcanic sequences in the central Mojave block Elizabeth R. Schermer Department that at least part, and possibly all, of the Fairview Valley For- mation is late Early Jurassic in age. We-marine rocks as Jurassic instead of Triassic suggests a period of uplift and erosion or nondeposition extending

Busby, Cathy

202

New heterodontosaurid specimens from the Lower Jurassic of southern Africa and the early  

E-print Network

New heterodontosaurid specimens from the Lower Jurassic of southern Africa and the early is best known from the Lower Jurassic upper `Stormberg Group' (upper Elliot and Clarens formations, the evolution of ornithischians during the Late Triassic and much of the Jurassic is poorly understood (e

203

Thermal maturity of the Upper Triassic-Middle Jurassic Shemshak Group (Alborz Range, Northern Iran)  

E-print Network

1 Thermal maturity of the Upper Triassic-Middle Jurassic Shemshak Group (Alborz Range, Northern of the Shemshak Group (Upper Triassic-Middle Jurassic) from fifteen localities along the Alborz Range of Northern deeply buried part of the Shemshak Group (i.e., Tazareh section) corresponds to Late Jurassic

Paris-Sud XI, Université de

204

Geophys. J. Int. (2003) 153, 2026 A first palaeomagnetic study of Jurassic formations from the Qaidam  

E-print Network

Geophys. J. Int. (2003) 153, 20­26 A first palaeomagnetic study of Jurassic formations from palaeomagnetic study on Upper Jurassic red beds collected at nine sites near Huatugou (38.46 N, 90.75 E a large-scale tectonic evolution of the Asian continent since the late Jurassic. This study suggests

Cogne, Jean-Pascal

205

PALEONTOLOGY AND PALEOENVIRONMENTS OF EARLY JURASSIC AGE STRATA IN THE WALTER KIDDE DINOSAUR PARK (NEW JERSEY, USA)  

E-print Network

REPRINT PALEONTOLOGY AND PALEOENVIRONMENTS OF EARLY JURASSIC AGE STRATA IN THE WALTER KIDDE OF EARLY JURASSIC AGE STRATA IN THE WALTER KIDDE DINOSAUR PARK (NEW JERSEY, USA) Paul E. Olsen Lamont is to provide an overview of the Jurassic age fossils from the site, and to place those remains

Olsen, Paul E.

206

JurassicCretaceous low paleolatitudes from the circum-Black Sea region (Crimea and Pontides) due to True Polar Wander  

E-print Network

Jurassic­Cretaceous low paleolatitudes from the circum-Black Sea region (Crimea and Pontides) due in the present-day Black Sea region. Our Eurasian data suggest the same low Late Jurassic to Early Cretaceous

Utrecht, Universiteit

207

Marine Jurassic lithostratigraphy of Thailand  

NASA Astrophysics Data System (ADS)

Marine Jurassic rocks of Thailand are well-exposed in the Mae Sot and Umphang areas and less extensively near Mae Hong Son, Kanchanaburi, Chumphon and Nakhon Si Thammarat, in the north, west, and south respectively. They are generally underlain unconformably by Triassic and overlain by Quaternary strata. Based mainly on five measured sections, fourteen new lithostratigraphic units are established: (in ascending order) Pa Lan, Mai Hung and Kong Mu Formations of the Huai Pong Group in the Mae Hong Son area; Khun Huai, Doi Yot and Pha De Formations of the Hua Fai Group in the Mae Sot area; Klo Tho, Ta Sue Kho, Pu Khloe Khi and Lu Kloc Tu Formations of the Umphang Group in the Umphang area; and the Khao Lak Formation in the Chumphon area. Mudstone, siltstone, sandstone, limestone and marl are the dominant lithologies. Mudstones, siltstones and sandstones are widespread; limestones are confined to the Mae Sot, Umphang, Kanchanaburi and Mae Hong Son areas; marls are found only in Mae Sot. The sequences are approximately 900 m thick in Mae Sot and 450 m thick in Umphang and are rather thinner in the other areas, particularly in the south. Based on ammonites, with additional data from bivalves and foraminifera, the marine Jurassic is largely Toarcian-Aalenian plus some Bajocian. Late Jurassic ages given previously for strata in the Mae Sot and Umphang areas have not been confirmed.

Meesook, A.; Grant-Mackie, J. A.

208

Middle Jurassic strata link Wallowa, Olds Ferry, and Izee terranes in the accreted Blue Mountains island arc, northeastern Oregon  

Microsoft Academic Search

Middle Jurassic strata atop the Wallowa terrane in northeastern Oregon link the Wallowa, Izee, and Olds Ferry terranes as related elements of a single long-lived and complex oceanic feature, the Blue Mountains island arc. Middle Jurassic strata in the Wallowa terrane include a dacitic ash-flow deposit and contain fossil corals and bivalves of North American affinity. Plant fossils in fluvial

James D. L. White; T. Vallier; G. D. Jr. Stanley; S. R. Ash; D. L. White

1992-01-01

209

Remarkable Fossils  

Microsoft Academic Search

ONE of the most remarkable collections of Wealden fossils ever seen, was lately on loan for a few days to the exhibition then open at Horsham, and is one that is not to be equalled by any at our public museums in the country. So remarkable is it that I am induced to give you a short description. As you

Thomas Wm. Cowan

1874-01-01

210

ICHNOTAXONOMY AND PALEOENVIRONMENTAL ANALYSIS OF TRACE FOSSILS IN THE LATE DEVONIAN CATSKILL FORMATION, NORTH-CENTRAL PENNSYLVANIA, USA  

E-print Network

The purpose of this thesis is to interpret the ichnotaxonomy, paleoenvironmental distribution, and paleoecological ramifications of trace fossils from the Frasnian to Famennian Catskill Formation (CF), north-central ...

Jones, Wade Tyler

2011-12-31

211

Presence of the dinosaur Scelidosaurus indicates Jurassic age for the Kayenta Formation (Glen Canyon Group, northern Arizona)  

NASA Astrophysics Data System (ADS)

The Glen Canyon Group (Moenave, Wingate, Kayenta and Navajo Formations) of northern Arizona represents an extensive outcrop of early Mesozoic age terrestrial sediments. The age of these formations has long been disputed because independent stratigraphic data from marine tie-ins, paleobotanical and palynological evidence, and radiometric calibrations have been scanty or absent. The fauna of the Kayenta Formation in particular has been problematic because it has appeared to contain both typical Late Triassic and Early Jurassic taxa Here I report that the principal evidence for Late Triassic taxa, dermal scutes previously assigned to an aetosaur, in fact belongs to the thyreophoran ornithischian dinosaur Scelidosaurus, previously known only as a washed-in form found in marine sediments in the Early Jurassic of England. The presence of this dinosaur represents the first vertebrate biostratigraphic tie-in of the Glen Canyon Group horizons with reliably dated marine deposits in Europe. Together with revised systematic assessments of other vertebrates and independent evidence from fossil pollen, it supports an Early Jurassic age for the Kayenta Formation and most or all of the Glen Canyon Group.

Padian, Kevin

1989-05-01

212

Olsen, P. E., 1986, Discoveryof earliest Jurassic reptile assemblage from Nova Scotia impliescatastrophicend to Triassic: Lamont (Newsletter),v. 12,p. 1-3. Discovery of Earliest Jurassic Reptile Assemblages from Nova Scotia  

E-print Network

Olsen, P. E., 1986, Discoveryof earliest Jurassic reptile assemblage from Nova Scotia impliescatastrophicend to Triassic: Lamont (Newsletter),v. 12,p. 1-3. Discovery of Earliest Jurassic Reptile Assemblages from Nova Scotia: Imply Catastrophic End to the Triassic LateTriassic and EarlyJurassic sediments

Olsen, Paul E.

213

New Ophthalmosaurid Ichthyosaurs from the European Lower Cretaceous Demonstrate Extensive Ichthyosaur Survival across the Jurassic-Cretaceous Boundary  

PubMed Central

Background Ichthyosauria is a diverse clade of marine amniotes that spanned most of the Mesozoic. Until recently, most authors interpreted the fossil record as showing that three major extinction events affected this group during its history: one during the latest Triassic, one at the Jurassic–Cretaceous boundary (JCB), and one (resulting in total extinction) at the Cenomanian-Turonian boundary. The JCB was believed to eradicate most of the peculiar morphotypes found in the Late Jurassic, in favor of apparently less specialized forms in the Cretaceous. However, the record of ichthyosaurs from the Berriasian–Barremian interval is extremely limited, and the effects of the end-Jurassic extinction event on ichthyosaurs remains poorly understood. Methodology/Principal Findings Based on new material from the Hauterivian of England and Germany and on abundant material from the Cambridge Greensand Formation, we name a new ophthalmosaurid, Acamptonectes densus gen. et sp. nov. This taxon shares numerous features with Ophthalmosaurus, a genus now restricted to the Callovian–Berriasian interval. Our phylogenetic analysis indicates that Ophthalmosauridae diverged early in its history into two markedly distinct clades, Ophthalmosaurinae and Platypterygiinae, both of which cross the JCB and persist to the late Albian at least. To evaluate the effect of the JCB extinction event on ichthyosaurs, we calculated cladogenesis, extinction, and survival rates for each stage of the Oxfordian–Barremian interval, under different scenarios. The extinction rate during the JCB never surpasses the background extinction rate for the Oxfordian–Barremian interval and the JCB records one of the highest survival rates of the interval. Conclusions/Significance There is currently no evidence that ichthyosaurs were affected by the JCB extinction event, in contrast to many other marine groups. Ophthalmosaurid ichthyosaurs remained diverse from their rapid radiation in the Middle Jurassic to their total extinction at the beginning of the Late Cretaceous. PMID:22235274

Fischer, Valentin; Maisch, Michael W.; Naish, Darren; Kosma, Ralf; Liston, Jeff; Joger, Ulrich; Kruger, Fritz J.; Perez, Judith Pardo; Tainsh, Jessica

2012-01-01

214

Jurassic accretion tectonics of Japan  

Microsoft Academic Search

The Jurassic accretionary complex and coeval granites in Japan represent remnants of the Jurassic arc-trench system developed between the Asian continent and Pacific Ocean. The Jurassic accretionary complex occurs as a large-scale nappe that is tectonically sandwiched be- tween the overlying pre-Jurassic nappes and underlying post-Jurassic nappes. By virtue of new research styles (microfossil mapping and chronometric mapping) the following

Yukio Isozaki

1997-01-01

215

Is the Jurassic (Yanshanian) intraplate tectonics of North China due to westward indentation of the North China Block?  

E-print Network

1 Is the Jurassic (Yanshanian) intraplate tectonics of North China due to westward indentation Jurassic-Early Cretaceous through three deformation phases coeval with syntectonic sedimentation, separated by two transtensional episodes coeval with magmatism. The Late Jurassic­Early Cretaceous tectonic event

Paris-Sud XI, Université de

216

Seismic evidence for the presence of Jurassic oceanic crust in the1 central Gulf of Cadiz (SW Iberian margin)2  

E-print Network

Seismic evidence for the presence of Jurassic oceanic crust in the1 central Gulf of Cadiz (SW as a transform margin during the Early Jurassic that37 followed the continental break-up in the Central Atlantic40 spreading in the North Atlantic at the Tithonian (late Jurassic-earliest Cretaceous). The41

Paris-Sud XI, Université de

217

Olsen, et al., 2002 From: McRoberts, C. A. and Olsen, P. E., 2002, Triassic-Jurassic  

E-print Network

Olsen, et al., 2002 From: McRoberts, C. A. and Olsen, P. E., 2002, Triassic-Jurassic Non. #12;p. 13 ASTRONOMICALLY CALIBRATED GPTS FOR THE LATE TRIASSIC AND EARLY JURASSIC BASED ON THE NEWARK Timescale (GPTS) for the Triassic and Early Jurassic based on scientific coring of the Newark basin (NY, NJ

Olsen, Paul E.

218

Jurassic Park Safety Audit  

NSDL National Science Digital Library

Using the first 30 minutes of the film Jurassic Park, the student will audit it for violations of safety rules and regulations, OSHA violations, and violations of HASP's. Access to the activity required free and quick registration with ATEEC.

2007-09-18

219

Jurassic Reef Park  

NSDL National Science Digital Library

This is a bilingual, educational website from Munich, Germany. The main feature is a virtual field trip to the reefs of the Jurassic period. Besides a view of the Jurassic reefs, their builders, and their ecological settings, there is also an emphasis on the importance of modern reefs as indicators of the state-of-health of the globe and evidence of how some changes in the composition of reefs may represent the forerunners of catastrophic, regional or global, environmental change.

Leinfelder, Reinhold

220

Jurassic Reef Park  

NSDL National Science Digital Library

Dr. Reinhold Leinfelder of the University of Stuttgart, Germany created this interesting site in English and German, offering a "virtual trip to the reefs of the Jurassic Period." In the Introduction, viewers will find background material and comparisons of modern and ancient reefs. Further information is provided in the sections on reef architecture, reef formation, Jurassic reefs, and reefs and global climate change. Although the English language is slightly quirky, the content and images more than compensate, making this a worthwhile site.

221

Jurassic conchostracans from Patagonia  

E-print Network

THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS September 16, 1970 Paper 50 JURASSIC CONCHOSTRACANS FROM PATAGONIA PAUL TASCH 1 and WOLFGANG VOLKHEIMER2 I Department of Geology, Wichita State University, Wichita, Kansas, Muse° A rgentino de... Ciencias Naturides "Bernar- dino Rivadavia," Buenos Aires, Argentina PART 1. PALEONTOLOGY AND PALEOECOLOGY PAUL TASCH ABSTRACT Two new species ( and three others) of the conchostracan genus Cyzicus are described and figured. All are Jurassic (Callovian...

Tasch, P.; Volkheimer, W.

1970-09-16

222

Fossil Halls: Timelines  

NSDL National Science Digital Library

Part of a larger virtual tour of the Museum's famed Fossil Halls, this Web site allows students to travel back in time to several prehistoric points in the history of Earth. At each, they'll find a fleshed-out portrait of the period's creatures and their environment. The eight periods students will visit, some of which include more than one point-in-time snapshot, are Pleistocene, Miocene, Oligocene, Eocene, Cretaceous, Jurassic, Permian and Devonian Periods.

223

Charcoal and fossil wood from palaeosols, sediments and artificial structures indicating Late Holocene woodland decline in southern Tibet (China)  

Microsoft Academic Search

Charcoal and fossil wood taken from palaeosols, sediments and artificial structures were analysed in order to evaluate the regional pedoanthracological potential and to obtain information on Holocene environmental changes, particularly on possible past tree occurrences in southern Tibet. This research was initiated by the question to what extent this area is influenced by past human impact. Even recent evaluations have

Knut Kaiser; Lars Opgenoorth; Werner H. Schoch; Georg Miehe

2009-01-01

224

?44/40Ca variations of seawater from Cenozoic and Mesozoic fossil corals  

NASA Astrophysics Data System (ADS)

Numerous archives including fossil carbonates, marine barite, and authigenic phosphates have shown that the Ca-isotope composition of seawater has varied throughout the Phanerozoic. Such changes are thought to be driven by oscillations between calcite seas and aragonite seas, with relatively heavy seawater ?44/40Ca occurring when aragonite deposition is favored and relatively light seawater ?44/40Ca when calcite deposition is favored[1,2]. While the Ca-isotope composition of Neogene and Late Paleogene seawater has been fairly well characterized, current records lack redundancy for ages >35Ma, and are sparsely sampled during the Late Mesozoic and Early Cenozoic. Fossil scleractinian corals may be good candidates for supplementing existing records of seawater Ca isotopes. Although the coral Ca-isotope effect has been shown to be somewhat variable between different taxa, it has also been shown that the Ca-isotope composition of scleractinians exhibits a weak temperature dependence, and is essentially independent of salinity and calcification rate[3]. We measured a suite of ~35 well-preserved fossil corals for Ca isotopes, ranging in age from Jurassic through Recent. We find that the ?44/40Ca seawater composition reconstructed from Neogene-age fossil corals is broadly consistent with existing records. However, Cretaceous and Late Jurassic fossil corals are ~1.1‰ lighter in ?44/40Ca than modern corals. The Cretaceous and Jurassic data support a record from Cretaceous-age authigenic phosphates, but indicate a ?44/40Ca of seawater that is ~0.8‰ lower than that inferred from fossil brachiopods and belemnites of similar ages. We are uncertain which record may best reflect the isotopic composition of seawater, but the differences between these reconstructions have implications for our current understanding of calcite and aragonite seas, and for the global calcium cycle. It is also possible that part of the depletion observed in Jurassic and Cretaceous age corals reflects a varying coral Ca-isotope effect as a result of changes in the seawater Ca concentration. [1] Blätter, C.L., et al. (2012) Geology, 40, 843-846. [2] F?rkas, J., et al. (2007) Geochimica et Cosmochimica Acta, 71, 5117-5134. [3] Pretet, C. et al. (2013) Chemical Geology, 340, 49-58.

Gothmann, A. O.; Higgins, J. A.; Blättler, C. L.; Stolarski, J.; Adkins, J. F.; Bender, M. L.

2013-12-01

225

Triassic/Jurassic faulting patterns of Conecuh Ridge, southwest Alabama  

SciTech Connect

Two major fault systems influenced Jurassic structure and deposition on the Conecuh Ridge, southwest Alabama. Identification and dating of these fault systems are based on seismic-stratigraphic interpretation of a 7-township grid in Monroe and Conecuh Counties. Relative time of faulting is determined by fault geometry and by formation isopachs and isochrons. Smackover and Norphlet Formations, both Late Jurassic in age, are mappable seismic reflectors and are thus reliable for seismicstratigraphic dating. The earlier of the 2 fault systems is a series of horsts and grabens that trends northeast-southwest and is Late Triassic to Early Jurassic in age. The system formed in response to tensional stress associated with the opening of the Atlantic Ocean. The resulting topography was a series of northeast-southwest-trending ridges. Upper Triassic Eagle Mills and Jurassic Werner Formations were deposited in the grabens. The later fault system is also a series of horsts and grabens trending perpendicular to the first. This system was caused by tensional stress related to a pulse in the opening of the Gulf of Mexico. Faulting began in Early Jurassic and continued into Late Jurassic, becoming progressively younger basinward. At the basin margin, faulting produced a very irregular shoreline. Submerged horst blocks became centers for shoaling or carbonate buildups. Today, these blocks are exploration targets in southwest Alabama.

Hutley, J.K.

1985-02-01

226

Thorough assessment of DNA preservation from fossil bone and sediments excavated from a late Pleistocene-Holocene cave deposit on Kangaroo Island, South Australia  

NASA Astrophysics Data System (ADS)

Fossils and sediments preserved in caves are an excellent source of information for investigating impacts of past environmental changes on biodiversity. Until recently studies have relied on morphology-based palaeontological approaches, but recent advances in molecular analytical methods offer excellent potential for extracting a greater array of biological information from these sites. This study presents a thorough assessment of DNA preservation from late Pleistocene-Holocene vertebrate fossils and sediments from Kelly Hill Cave Kangaroo Island, South Australia. Using a combination of extraction techniques and sequencing technologies, ancient DNA was characterised from over 70 bones and 20 sediment samples from 15 stratigraphic layers ranging in age from >20 ka to ˜6.8 ka. A combination of primers targeting marsupial and placental mammals, reptiles and two universal plant primers were used to reveal genetic biodiversity for comparison with the mainland and with the morphological fossil record for Kelly Hill Cave. We demonstrate that Kelly Hill Cave has excellent long-term DNA preservation, back to at least 20 ka. This contrasts with the majority of Australian cave sites thus far explored for ancient DNA preservation, and highlights the great promise Kangaroo Island caves hold for yielding the hitherto-elusive DNA of extinct Australian Pleistocene species.

Haouchar, Dalal; Haile, James; McDowell, Matthew C.; Murray, Dáithí C.; White, Nicole E.; Allcock, Richard J. N.; Phillips, Matthew J.; Prideaux, Gavin J.; Bunce, Michael

2014-01-01

227

TRIASSIC AND JURASSIC FORMATIONS OF THE NEWARK BASIN  

E-print Network

TRIASSIC AND JURASSIC FORMATIONS OF THE NEWARK BASIN PAUL E. OLSEN Bingham Laboratories, Department of Biology, Yale University, New Haven, Connecticut Abstract Newark Supergroup deposits of the Newark Basin (or lack thereof). Fossils are abundant in the sedimentary formations of the Newark Basin and provide

Olsen, Paul E.

228

Skull of a Jurassic ankylosaur (Dinosauria)  

Microsoft Academic Search

The origin and early evolution of many major dinosaur groups are poorly known because specimens are rare. One of these groups, the Ankylosauria, or armour-plated dinosaurs, is best known from well-preserved specimens from the Upper Cretaceous period of Asia and North America. Here we describe a well-preserved skull of an earlier, Late Jurassic ankylosaur, which will be important in clarifying

Kenneth Carpenter; Clifford Miles; Karen Cloward

1998-01-01

229

Paleontology, paleoclimatology and paleoecology of the late middle miocene Musselshell Creek flora, Clearwater County Idaho. A preliminary study of a new fossil flora  

SciTech Connect

The Musselshell Creek flora (12.0-10.5 Ma) of northern Idaho is used to reconstruct paleoclimatic and paleoecologic parameters of the Pacific Northwest during the late Middle Miocene. Other megafossil and microfossil floral records spanning 12.0-6.4 Ma are unknown from this region. The Musselshell Creek fossil flora, previously undescribed, is preserved in lacustrine clays and sediments that accumulated in a narrow valley surrounded by rugged terrain. Dominant taxa include dicotyledons and conifers. Most of the leaves are preserved as impressions or compressions. Some fossil leaves retained their original pigmentation, cellular anatomy, and organic constituents. Other fossils include excellent remains of pollen and spores, dispersed leaf cuticle, pyritized wood, and disarticulated fish bones. A destructive statistical analysis of one block of sediment, approximately 30 cm x 45 cm (1.5 sq. ft) recovered 14 orders, 23 families, and 34 genera of spermatophyte plant fossils. These floral elements are compared with two other earlier Miocene floras which were similarly sampled. Common megafossil genera include Quercus, Zizy-phoides, Taxodium, Alnus, Castanea, Magnolia, Acer, Ex-bucklandia, Sequoia, Populus, and Betula. The rare occurrence of Ginkgo leaves is a first record of this taxon in the Idaho Miocene. Additional plant taxa, are represented by palynomorphs. Common pollen taxa are Pinus, Abies, Carya, Quercus, and Tilia. Most of the megafossil and microfossil flora assemblage is characteristic of a streambank to floodplain environment that existed in a warm to cool temperate climate similar to the modern Mid-Atlantic coast of the United States. 47 refs., 5 figs., 4 tabs.

Baghai, N.L. [Univ. of Texas, Austin, TX (United States); Jorstad, R.B. [Eastern Illinois Univ., Charleston, IL (United States)

1995-10-01

230

X-ray Synchrotron Microtomography of a silicified Jurassic Cheirolepidiaceae (Conifer) cone: histology and morphology of Pararaucaria collinsonae sp. nov.  

PubMed Central

We document a new species of ovulate cone (Pararaucaria collinsonae) on the basis of silicified fossils from the Late Jurassic Purbeck Limestone Group of southern England (Tithonian Stage: ca. 145 million years). Our description principally relies on the anatomy of the ovuliferous scales, revealed through X-ray synchrotron microtomography (SRXMT) performed at the Diamond Light Source (UK). This study represents the first application of SRXMT to macro-scale silicified plant fossils, and demonstrates the significant advantages of this approach, which can resolve cellular structure over lab-based X-ray computed microtomography (XMT). The method enabled us to characterize tissues and precisely demarcate their boundaries, elucidating organ shape, and thus allowing an accurate assessment of affinities. The cones are broadly spherical (ca. 1.3 cm diameter), and are structured around a central axis with helically arranged bract/scale complexes, each of which bares a single ovule. A three-lobed ovuliferous scale and ovules enclosed within pocket-forming tissue, demonstrate an affinity with Cheirolepidiaceae. Details of vascular sclerenchyma bundles, integument structure, and the number and attachment of the ovules indicate greatest similarity to P. patagonica and P. carrii. This fossil develops our understanding of the dominant tree element of the Purbeck Fossil Forest, providing the first evidence for ovulate cheirolepidiaceous cones in Europe. Alongside recent discoveries in North America, this significantly extends the known palaeogeographic range of Pararaucaria, supporting a mid-palaeolatitudinal distribution in both Gondwana and Laurasia during the Late Jurassic. Palaeoclimatic interpretations derived from contemporaneous floras, climate sensitive sediments, and general circulation climate models indicate that Pararaucaria was a constituent of low diversity floras in semi-arid Mediterranean-type environments. PMID:25374776

Steart, David C.; Spencer, Alan R.T.; Garwood, Russell J.; Hilton, Jason; Munt, Martin C.; Needham, John

2014-01-01

231

Jurassic paleomagnetic constraints on the collision of the north and south China blocks  

Microsoft Academic Search

This paper reports a paleomagnetic study of Jurassic rocks from the Ordos Basin in the North China Block (NCB). A recent remagnetization and a high-temperature and\\/or high-coercivity component with dual polarities have been isolated. The Middle Jurassic pole (74°N, 233°E, A95=5°) is roughly consistent with previous results, and the Lower Jurassic pole (82°N, 286°E, A95=7°) is located between the late

Zhenyu Yang; Vincent Courtillot; Jean Besse; Xinghua Ma; Lisheng Xing; Shujin Xu; Jingxing Zhang

1992-01-01

232

Jurassic crustal deformation in west-central part of Colorado Plateau  

SciTech Connect

Although the Jurassic Period is commonly thought of as a time of tectonic quiescence, updated isopach maps and new sedimentologic information indicate that it was a time of notable crustal deformation on the Colorado Plateau. A significant change in structural style occurred in Middle Jurassic time, especially during the erosion interval that produced the J-3 unconformity. Prior to late Middle Jurassic time, the region had been tilted westward and structural troughs formed in the area of the present-day Circle Cliffs uplift and in the vicinity of the Circle Cliffs and Black Mesa regions were uplifted and the nearby Henry and Kaiparowits regions began to be downwarped as troughs or basins. It cannot be determined if or how the present-day monoclines flexed during the Jurassic. However, the direction of structural tilt across these areas changed from west side down to east side down during the late Middle and early Late Jurassic. The Monument region, the largest and most persistent structural element in the region, changed from a structural bench to a positive structure in the early Late Jurassic. In most cases the positive structures subsided more slowly than adjacent downwarps. Two exceptions during the Late Jurassic are the Black Mesa and Emery uplifts. These are the only uplifts that actually rose above the level of sediment accumulation. Jurassic rocks are not known to contain significant hydrocarbon resources in this region, but their tectonic history may offer clues to the structural history of underlying Paleozoic strata, which are the primary hydrocarbon exploration targets.

Peterson, F.

1985-05-01

233

Dietary niche partitioning among fossil bovids in late Miocene C 3 habitats: Consilience of functional morphology and stable isotope analysis  

Microsoft Academic Search

Teeth of late Miocene bovids referred to Bovini and “Boselaphini” were subjected to enamel stable carbon and oxygen isotope analysis to test paleoecological reconstructions based on dental morphology. Teeth of Bovini possess derived characters–including larger size, higher crowns, and increased enamel surface area–that are indicative of feeding on a more fibrous and gritty diet, probably grass. In contrast, teeth of

Faysal Bibi

2007-01-01

234

Exploring Jurassic Park.  

ERIC Educational Resources Information Center

Describes several student-tested activities built around "Jurassic Park." The activities feature students engaged in role-playing scenarios, investigative research projects, journal writing and communications skills activities, cooperative learning groups, and learning experiences that make use of reading skills and mathematical knowledge. (PR)

Simmons, Patricia E.; Wiley, Clyde

1993-01-01

235

Fossil mice and rats show isotopic evidence of niche partitioning and change in dental ecomorphology related to dietary shift in Late Miocene of Pakistan.  

PubMed

Stable carbon isotope analysis in tooth enamel is a well-established approach to infer C3 and C4 dietary composition in fossil mammals. The bulk of past work has been conducted on large herbivorous mammals. One important finding is that their dietary habits of fossil large mammals track the late Miocene ecological shift from C3 forest and woodland to C4 savannah. However, few studies on carbon isotopes of fossil small mammals exist due to limitations imposed by the size of rodent teeth, and the isotopic ecological and dietary behaviors of small mammals to climate change remain unknown. Here we evaluate the impact of ecological change on small mammals by fine-scale comparisons of carbon isotope ratios (?(13)C) with dental morphology of murine rodents, spanning 13.8 to ?2.0 Ma, across the C3 to C4 vegetation shift in the Miocene Siwalik sequence of Pakistan. We applied in-situ laser ablation GC-IRMS to lower first molars and measured two grazing indices on upper first molars. Murine rodents yield a distinct, but related, record of past ecological conditions from large herbivorous mammals, reflecting available foods in their much smaller home ranges. In general, larger murine species show more positive ?(13)C values and have higher grazing indices than smaller species inhabiting the same area at any given age. Two clades of murine rodents experienced different rates of morphological change. In the faster-evolving clade, the timing and trend of morphological innovations are closely tied to consumption of C4 diet during the vegetation shift. This study provides quantitative evidence of linkages among diet, niche partitioning, and dental morphology at a more detailed level than previously possible. PMID:23936324

Kimura, Yuri; Jacobs, Louis L; Cerling, Thure E; Uno, Kevin T; Ferguson, Kurt M; Flynn, Lawrence J; Patnaik, Rajeev

2013-01-01

236

Fossil Mice and Rats Show Isotopic Evidence of Niche Partitioning and Change in Dental Ecomorphology Related to Dietary Shift in Late Miocene of Pakistan  

PubMed Central

Stable carbon isotope analysis in tooth enamel is a well-established approach to infer C3 and C4 dietary composition in fossil mammals. The bulk of past work has been conducted on large herbivorous mammals. One important finding is that their dietary habits of fossil large mammals track the late Miocene ecological shift from C3 forest and woodland to C4 savannah. However, few studies on carbon isotopes of fossil small mammals exist due to limitations imposed by the size of rodent teeth, and the isotopic ecological and dietary behaviors of small mammals to climate change remain unknown. Here we evaluate the impact of ecological change on small mammals by fine-scale comparisons of carbon isotope ratios (?13C) with dental morphology of murine rodents, spanning 13.8 to ?2.0 Ma, across the C3 to C4 vegetation shift in the Miocene Siwalik sequence of Pakistan. We applied in-situ laser ablation GC-IRMS to lower first molars and measured two grazing indices on upper first molars. Murine rodents yield a distinct, but related, record of past ecological conditions from large herbivorous mammals, reflecting available foods in their much smaller home ranges. In general, larger murine species show more positive ?13C values and have higher grazing indices than smaller species inhabiting the same area at any given age. Two clades of murine rodents experienced different rates of morphological change. In the faster-evolving clade, the timing and trend of morphological innovations are closely tied to consumption of C4 diet during the vegetation shift. This study provides quantitative evidence of linkages among diet, niche partitioning, and dental morphology at a more detailed level than previously possible. PMID:23936324

Kimura, Yuri; Jacobs, Louis L.; Cerling, Thure E.; Uno, Kevin T.; Ferguson, Kurt M.; Flynn, Lawrence J.; Patnaik, Rajeev

2013-01-01

237

Jurassic crustal deformation in west-central part of Colorado Plateau  

Microsoft Academic Search

Although the Jurassic Period is commonly thought of as a time of tectonic quiescence, updated isopach maps and new sedimentologic information indicate that it was a time of notable crustal deformation on the Colorado Plateau. A significant change in structural style occurred in Middle Jurassic time, especially during the erosion interval that produced the J-3 unconformity. Prior to late Middle

1985-01-01

238

Fossil vertebrates from Antigua, Lesser Antilles: Evidence for late Holocene human-caused extinctions in the West Indies  

PubMed Central

Vertebrate remains recovered from a limestone fissure filling on Antigua, Lesser Antilles, are associated with radiocarbon dates ranging from 4300 to 2500 yr B.P., contemporaneous with the earliest aboriginal human occupation of the island. Nine taxa of lizards, snakes, birds, bats, and rodents (one-third of the total number of species represented as fossils) are either completely extinct or have never been recorded historically from Antigua. These extinctions came long after any major climatic changes of the Pleistocene and are best attributed to human-caused environmental degradation in the past 3500 yr. Such unnatural influences have probably altered patterns of distribution and species diversity throughout the West Indies, thus rendering unreliable the data traditionally used in ecological and biogeographic studies that consider only the historically known fauna. PMID:16593490

Steadman, David W.; Pregill, Gregory K.; Olson, Storrs L.

1984-01-01

239

Jurassic mimicry between a hangingfly and a ginkgo from China  

PubMed Central

A near-perfect mimetic association between a mecopteran insect species and a ginkgoalean plant species from the late Middle Jurassic of northeastern China recently has been discovered. The association stems from a case of mixed identity between a particular plant and an insect in the laboratory and the field. This confusion is explained as a case of leaf mimesis, wherein the appearance of the multilobed leaf of Yimaia capituliformis (the ginkgoalean model) was accurately replicated by the wings and abdomen of the cimbrophlebiid Juracimbrophlebia ginkgofolia (the hangingfly mimic). Our results suggest that hangingflies developed leaf mimesis either as an antipredator avoidance device or possibly as a predatory strategy to provide an antiherbivore function for its plant hosts, thus gaining mutual benefit for both the hangingfly and the ginkgo species. This documentation of mimesis is a rare occasion whereby exquisitely preserved, co-occurring fossils occupy a narrow spatiotemporal window that reveal likely reciprocal mechanisms which plants and insects provide mutual defensive support during their preangiospermous evolutionary histories. PMID:23184994

Wang, Yongjie; Labandeira, Conrad C.; Shih, Chungkun; Ding, Qiaoling; Wang, Chen; Zhao, Yunyun; Ren, Dong

2012-01-01

240

Journal of the Geological Society, London, Vol. 161, 2004, pp. 365379. Printed in Great Britain. Sea-level change and facies development across potential TriassicJurassic  

E-print Network

or a global context. Keywords: Triassic, Jurassic, extinction, sea-level change. Period boundaries commonly. 365 Sea-level change and facies development across potential Triassic­Jurassic boundary horizons, SW: The Late Triassic to Early Jurassic aged succession of SW Britain (the Penarth and lower Lias Groups

Hesselbo, Stephen P.

241

movements in Triassic theropod dinosaurs. Nature 339, 141144 (1999). 8. Gierlinski, G. Avialian theropod tracks from the Early Jurassic strata of Poland. Zubia 14, 7987 (1996).  

E-print Network

theropod tracks from the Early Jurassic strata of Poland. Zubia 14, 79­87 (1996). 9. Rainforth, E. C. Late Triassic­Early Jurassic dinosaur ichnofaunas, eastern North America and Southern Africa. J. Vert. Paleo. 21, Jurassic and Cretaceous time scale. SEPM Spec. Publ. 54, 95­126 (1995). 16. Kent, D. V. & Olsen, P. E

Gribble, Paul

242

Progress in Natural Science Vol.16 (Special 1ssue), June 2006 Marine and Non-marine Jurassic : Boundary Events and Correlation  

E-print Network

-marine Jurassic : Boundary Events and Correlation Jingeng SHA'" , Nicol MORT ON^, Yongdong WANG' , Paul OLSEN) The Jurassic, spanning about 201 to 145 is an important period in geological history for the evolution of life during the Middle-Late Jurassic, happened in middle and east Asia, and parts of North America. (3) Huge

Olsen, Paul E.

243

Fern ecological implications from the Lower Jurassic in Western Hubei, China  

Microsoft Academic Search

The Lower Jurassic Hsiangchi Formation in western Hubei, China is well known for its abundant and diverse fossil ferns, including Marattiaceae, Osmundaceae, Matoniaceae, Dipteridaceae and Dicksoniaceae. Through recent collections and investigation of the fossil plants in this area, an autochthonous\\/hypoautochthonous fern community has been recognised from the upper part of the Hsiangchi Formation in Zigui, Hubei. This community is dominated

Yongdong Wang

2002-01-01

244

Associated terrestrial and marine fossils in the late-glacial Presumpscot Formation, southern Maine, USA, and the marine reservoir effect on radiocarbon ages  

NASA Astrophysics Data System (ADS)

Excavations in the late-glacial Presumpscot Formation at Portland, Maine, uncovered tree remains and other terrestrial organics associated with marine invertebrate shells in a landslide deposit. Buds of Populus balsamifera (balsam poplar) occurred with twigs of Picea glauca (white spruce) in the Presumpscot clay. Tree rings in Picea logs indicate that the trees all died during winter dormancy in the same year. Ring widths show patterns of variation indicating responses to environmental changes. Fossil mosses and insects represent a variety of species and wet to dry microsites. The late-glacial environment at the site was similar to that of today's Maine coast. Radiocarbon ages of 14 tree samples are 11,907 ± 31 to 11,650 ± 50 14C yr BP. Wiggle matching of dated tree-ring segments to radiocarbon calibration data sets dates the landslide occurrence at ca. 13,520 + 95/-20 cal yr BP. Ages of shells juxtaposed with the logs are 12,850 ± 65 14C yr BP ( Mytilus edulis) and 12,800 ± 55 14C yr BP ( Balanus sp.), indicating a marine reservoir age of about 1000 yr. Using this value to correct previously published radiocarbon ages reduces the discrepancy between the Maine deglaciation chronology and the varve-based chronology elsewhere in New England.

Thompson, Woodrow B.; Griggs, Carol B.; Miller, Norton G.; Nelson, Robert E.; Weddle, Thomas K.; Kilian, Taylor M.

2011-05-01

245

Jurassic platform development, northwestern Gulf of Mexico  

SciTech Connect

Triassic and Early Jurassic rifting set the stage for the subsequent development of carbonate platforms in the Late Jurassic. These platforms formed along the interior margins of salt basins separated from the main ancestral Gulf of Mexico by a series of positive features. A major sea level rise, after deposition of the Louann Salt (late Callovian), drowned the interior salt basins around the margins of the Gulf of Mexico, leading to an anoxic event. Organic-rich sediments of the lower Smackover were deposited as a basin-fill sequence, forming one of the major hydrocarbon source rocks of the region. As sea level rise slowed in the late Oxfordian, carbonate production began to catch up with sea level rise along the basin margins, leading to the initial development of a rimmed carbonate platform. The platform margin was marked by high-energy ooid grainstones, while crustacean pellet muds were deposited in the platform interior. A high-energy ooid-dominated platform (upper Smackover) developed in the late Oxfordian when sea level reached a standstill. During the subsequent Kimmeridgian sea level rise, a second rimmed carbonate platform, the Haynesville, was developed. During the initial rise, grainstones were deposited on the platform margin, while the interior was dominated by evaporites (Buckner) and siliciclastics. As sea level slowed and reached a standstill, the platform margin facies extended shoreward (Gilmer) and a high-energy platform, analogous to the upper Smackover, was formed. The Smackover and Haynesville platforms of the northwestern gulf show a parallel evolution in response to cyclic changes in Upper Jurassic sea level.

Moore, C.H. Jr.

1987-05-01

246

The Earliest Case of Extreme Sexual Display with Exaggerated Male Organs by Two Middle Jurassic Mecopterans  

PubMed Central

Background Many extant male animals exhibit exaggerated body parts for display, defense or offence in sexual selection, such as male birds of paradise showing off colorful and elegant feathers and male moose and reindeers bearing large structured antlers. For insects, male rhinoceros and stag beetles have huge horn-like structure for fighting and competition and some male Leptopanorpa scorpionflies have very long abdominal terminal segments for sexual display and competition. Fossil records of insects having exaggerated body parts for sexual display are fairly rare. One example is two male holcorpids with elongate abdominal segments from sixth (A6) to eighth (A8) and enlarged male genitalia from Eocene, suggesting evolution of these characters occurred fairly late. Principal Findings We document two mecopterans with exaggerated male body parts from the late Middle Jurassic Jiulongshan Formation in northeastern China. Both have extremely extended abdominal segments from A6 to A8 and enlarged genitalia, which might have been used for sexual display and, to less extent, for fighting with other males in the competition for mates. Although Fortiholcorpa paradoxa gen. et sp. nov. and Miriholcorpa forcipata gen. et sp. nov. seem to have affinities with Holcorpidae, we deem both as Family Incertae sedis mainly due to significant differences in branching pattern of Media (M) veins and relative length of A8 for F. paradoxa, and indiscernible preservation of 5-branched M veins in hind wing for M. forcipata. Conclusions/Significance These two new taxa have extended the records of exaggerated male body parts of mecopterans for sexual display and/or selection from the Early Eocene to the late Middle Jurassic. The similar character present in some Leptopanorpa of Panorpidae suggests that the sexual display and/or sexual selection due to extremely elongated male abdominal and sexual organs outweigh the negative impact of bulky body and poor mobility in the evolutionary process. PMID:23977031

Wang, Qi; Shih, Chungkun; Ren, Dong

2013-01-01

247

The Lower Jurassic of the Eastern Caspian region and the Middle Caspian Basin: Lithology, facies, taphonomy  

NASA Astrophysics Data System (ADS)

Lithofacies of the productive Upper Triassic-Lower Jurassic deposits of the Eastern Caspian region, studied in wells on the Caspian coast and exposed in the outcrops of the Mountainous Mangyshlak, are described and analyzed. The similarity of the structure of the Mesozoic sedimentary beds of the Middle Caspian Basin and of those of the land adjacent to its eastern coast is confirmed. Comparative analysis of lithofacies allowed the reconstruction of the paleogeographic setting and depositional environments in the studied region during the Early Jurassic. A unique fossil plant occurrence is discovered in the upper part of the Lower Jurassic series (in the lower subformation of the Kokala Formation; Eastern Caspian region). Fossil plant taphonomy and the lithology of host rocks in the occurrence resulted from unusual paleogeographic settings that existed in the Middle Caspian Basin at the time of the Early-Middle Jurassic boundary.

Kiritchkova, A. I.; Nosova, N. V.

2014-09-01

248

Jurassic epithermal Au–Ag deposits of Patagonia, Argentina  

Microsoft Academic Search

Important precious metal deposits have been discovered during the last 10 years in the Deseado Massif region of Patagonia, Argentina. This region is a plateau consisting of Middle to Upper Jurassic volcanic rocks that host fracture-controlled epithermal Au–Ag mineralization. These mineral deposits represent low sulfidation type hydrothermal systems and formed following the main period of volcanism, probably during the Late

I. B Schalamuk; M Zubia; A Genini; R. R Fernandez

1997-01-01

249

Tracing climatic conditions during the deposition of late Cretaceous-early Eocene phosphate beds in Morocco by geochemical compositions of biogenic apatite fossils  

NASA Astrophysics Data System (ADS)

Morocco's Western Atlantic coast was covered by shallow seas during the late Cretaceous-early Eocene when large amount of phosphate rich sediments were deposited. This time interval envelops a major part of the last greenhouse period and gives the opportunity to study the event's characteristics in shallow water settings. These phosphate deposits are extremely rich in vertebrate fossils, while other types of fossils are rare or often poorly preserved. Hence the local stratigraphy is based on the most abundant marine vertebrate fossils, on the selachian fauna (sharks and rays). Our geochemical investigations were also carried out on these remains, though in some cases frequently found coprolites were involved as well. The main goal of our study was to test whether stable isotope compositions (?18OPO4, ?13C) of these fossils reflect any of the hyperthermal events and/or the related perturbations in the carbon cycle during the early Paleogene (Lourens et al. 2005) and whether these geochemical signals can be used to refine the local stratigraphy. Additionally, the samples were analyzed for trace element composition in order to better assess local taphonomy and burial conditions. The samples came from two major phosphate regions, the Ouled Abdoun and the Ganntour Basins and they were collected either directly on the field during excavations (Sidi Chennane) or were obtained from museum collections with known stratigraphical position (Sidi Daoui, Ben Guerrir). The phosphate oxygen isotopic compositions of shark teeth display large range across the entire series (18.5-22.4 ) which can partly be related to the habitat of sharks. For instance the genus Striatolamnia often yielded the highest ?18O values indicating possible deep water habitat. Despite the large variation in ?18O values, a general isotope trend is apparent. In the Maastrichtian after a small negative shift, the ?18O values increase till the Danian from where the trend decrease till the Ypresian. The latter negative shift can be linked to the globally recognized Early Eocene Climatic Optimum (Zachos et al., 2001). In terms of carbon isotopic composition, shark teeth enameloid yielded often positive ?13C values, while dentine are always negative and sometimes following clear trend along the series. Coprolites have similar values to dentine, however they display greater variation reflecting the burial milieu and the special environment of phosphatization with the intensive organic matter recycling. Bone-beds show even more variations that could be caused by reworked specimens and also possible enhanced oxidation of organic matter at these levels. Nevertheless, the Sidi Chennane section shows a negative ?13C trend in the early Ypresian, which is compatible with global observations at the time. Moreover, the lowest ?13C values are from the transitional layer between the Ypresian and Thanetian beds which might relate to the Paleocene-Eocene boundary event, though it must be further confirmed. All the fossils display very similar rare earth element (REE) distribution that resembles typical seawater pattern with negative Ce-anomaly and heavy REE enrichment. However the large amount of analyses revealed a general drift in the magnitude of the Ce-anomaly from the older to younger beds that can be used in paleoenvironmental reconstruction.

Kocsis, L.; Gheerbrant, E.; Mouflih, M.; Cappetta, H.; Yans, J.; Ulianov, A.; Amaghzaz, M.

2012-04-01

250

A new sphenodontian (Lepidosauria: Rhynchocephalia) from the Late Triassic of Argentina and the early origin of the herbivore opisthodontians.  

PubMed

Sphenodontians were a successful group of rhynchocephalian reptiles that dominated the fossil record of Lepidosauria during the Triassic and Jurassic. Although evidence of extinction is seen at the end of the Laurasian Early Cretaceous, they appeared to remain numerically abundant in South America until the end of the period. Most of the known Late Cretaceous record in South America is composed of opisthodontians, the herbivorous branch of Sphenodontia, whose oldest members were until recently reported to be from the Kimmeridgian-Tithonian (Late Jurassic). Here, we report a new sphenodontian, Sphenotitan leyesi gen. et sp. nov., collected from the Upper Triassic Quebrada del Barro Formation of northwestern Argentina. Phylogenetic analysis identifies Sphenotitan as a basal member of Opisthodontia, extending the known record of opisthodontians and the origin of herbivory in this group by 50 Myr. PMID:24132307

Martínez, Ricardo N; Apaldetti, Cecilia; Colombi, Carina E; Praderio, Angel; Fernandez, Eliana; Santi Malnis, Paula; Correa, Gustavo A; Abelin, Diego; Alcober, Oscar

2013-12-01

251

Jurassic hydrocarbon exploration of southern Florida  

SciTech Connect

South Florida Jurassic exploration has been overlooked as a viable exploration target due to lack of data and plate-tectonics application. In Florida, {open_quotes}basement{close_quotes} is defined as crystalline, igneous, metamorphic, and unmetamorphosed sediments of Paleozoic age. Age-dating of zircons has proven that the Florida lower Paleozoic terrane is not akin to that of North America but is part of the West African Guinean shield. Previous published reconstructions of late Paleozoic fits of crustal plates and continents have failed to account for the differences in peninsula Florida basement and the geologic and tectonic continuities of peninsula Florida, Yucatan, Cuba, Hispaniola, and Bahamas. Pre-Atlantic reconstruction of the Gulf of Mexico in this study proposes that there was a Florida connection to Yucatan-Cuba-Africa during the Triassic. This reconstruction also shows that the Jurassic sediments that are well known in the northern Gulf Coast should have been deposited in similar depositional environments in southern Florida. Deep drilling on the Florida peninsula has confirmed this hypothesis. By using plate tectonic reconstruction based on the rising of the North Atlantic Ocean and evidence from petrology of basement samples from deep wells together with petrographic analyses of Jurassic sediments, a Smackover-equivalent exploration play can be developed. Petrographic and petrophysical analysis of these wells that have encountered Jurassic marine shales, anhydrite, dolomite, carbonate, and elastic sediments has determined that these sediments are from shallow-water subtidal, tidal, intertidal, and supratidal environments. Excellent gas shows, oil stain in the pores and high TOC values in the marine shales, indicate that large accumulations of hydrocarbon are present.

Mitchell-Tapping, H.J. [Retog, Inc., DeSoto, TX (United States)

1994-09-01

252

The Late Pleistocene-Holocene community development in Central and SE-Europe in direct fossil record: scope of the approach, common patterns and inter-regional differences.  

NASA Astrophysics Data System (ADS)

The information provided by modern instrumental approaches (molecular phylogeography, ancient DNA analyses, large scale radiocarbon datings etc.) refined the knowledge on Late Quaternary faunal development and range history of particular taxa in essential way. Nevertheless, the direct fossil record remains still an essential substrate in study of that topics, and to reveal all the information, that it may provide, and integrate it with the outputs of the other approaches presents one of the essential aim of the present meeting. Unfortunately, the immediate use of fossil record for the paleoecologic and paleobiogeographic inferences is often limited by its fragmentarity (both in temporal and spatial respects), taphonomic influences and/or locally specific post-sedimentary effects which all may bias it in a considerable degree. Hence, each particular record is to be carefully reexamined in respect to all factor which may bias it - unfortunately, often it is not too easy to respond that task, particularly when the record is retrived from secondary sources. It should also be remembered that the records representing narrow time slices without a robust lithostratigraphic context do not provide any information on the historical and contextual setting of the respective faunal situation. Such information that is essential for reconstructions of paleobiogeography of community development and similar locally-sensitive phenomena can only be retrived from the continuous sedimentary series which establish the sequence of particular faunal events by direct superposition. A sufficiently dense network of such series provides than a possibility of direct inter-regional comparisons and a high resolution information on the paleobiogeography of the Late Pleistocene-Holocene rearrangements of mammalian communities, local variation in history of particular species and its community context. We illustrate productivity of such approach on with aid of the fossil record obtained from continuous sedimentary sequences from different regions of Czech Republic and Slovakia (850 community samples, 29,800 MNI) and neighbouring countries of Central Europe. Despite common general trends we demonstrated stricking local and regional specificities. Among other they include (a) continuous survival of several woodland elements (Clethrionomys glareolus, Sorex araneus, Micotus subterraneus, Microtus agrestis) throughout Weichselian (including LGM) in the Carpathians, (b) prolonged survival of the glacial elements Ochotona pusilla and Microtus gregalis in Pannonian basin and (c) Dicrostonyx gulielmi in the Carpathian foredeep, contrasting to (d) the early disappearance of them in S-Germany and Bohemia, and (e) similar difference were found also in other cenologic traits. While the glacial communities were nearly homogenous in their structure throughout whole the region, the Holocene development produced a considerable faunal provincialism, which was the most pronounced during Boreal. In contrast to central Europe, the available sequences from the SE-Europe and Asia Minor show only minute faunal changes during the Vistulian and Holocene, no essential rearrangements in community structure were observed (at least as the core species are concerned) and except for Lagurus no glacial immigrant did invade the region. At the same time a degree of local provincialism was continuously high and, in a regional scale, it continuously exceeded that of the Boreal central Europe.

Horacek, Ivan; Lozek, Vojen

2010-05-01

253

Jurassic Polar Movement Relative to North America  

Microsoft Academic Search

Previous palcomagnetic studies of Jurassic rocks have not given concordant results and have led to the conclusion that the Jurassic pole position was possibly close to the present geographic pole. To test that supposition, the Kayenta, Carmel, Entrada, and Summerville formations were sampled from the extensive Jurassic sedimentary sequence in eastern Utah. The Lower and Upper Jurassic Kayenta and Summerville

ANY C. E. HELSLEY

1972-01-01

254

Jurassic faults of southwest Alabama and offshore areas  

SciTech Connect

Four fault groups affecting Jurassic strata occur in the southwest and offshore Alabama areas. They include the regional basement rift trend, the regional peripheral fault trend, the Mobile graben fault system, and the Lower Mobile Bay fault system. The regional basement system rift and regional peripheral fault trends are distinct and rim the inner margin of the eastern Gulf Coastal Plain. The regional basement rift trend is genetically related to the breakup of Pangea and the opening of the Gulf of Mexico in the Late Triassic-Early Jurassic. This fault trend is thought to have formed contemporaneously with deposition of Late Triassic-Early Jurassic Eagle Mills Formation and to displace pre-Mesozoic rocks. The regional peripheral fault trend consists of a group of en echelon extensional faults that are parallel or subparallel to regional strike of Gulf Coastal Plain strata and correspond to the approximate updip limit of thick Louann Salt. Nondiapiric salt features are associated with the trend and maximum structural development is exhibited in the Haynesville-Smackover section. No hydrocarbon accumulations have been documented in the pre-Jurassic strata of southwest and offshore Alabama. Productive hydrocarbon reservoirs occur in Jurassic strata along the trends of the fault groups, suggesting a significant relationship between structural development in the Jurassic and hydrocarbon accumulation. Hydrocarbon traps are generally structural or contain a major structural component and include salt anticlines, faulted salt anticlines, and extensional fault traps. All of the major hydrocarbon accumulations are associated with movement of the Louann Salt along the regional peripheral fault trend, the Mobile graben fault system, or the Lower Mobile Bay fault system.

Mink, R.M.; Tew, B.H.; Bearden, B.L.; Mancini, E.A. (Geological Survey of Alabama, Tuscaloosa (United States))

1991-03-01

255

Ostracoda (marine\\/nonmarine) and palaeoclimate history in the Upper Jurassic of Central Europe and North America  

Microsoft Academic Search

The role of Ostracoda in determining climate developments in the Upper Jurassic of Central Europe and North America is reviewed, based upon two different studies. The Late Jurassic is a period of time for which a change from a humid to a more arid climate has been suggested for several parts of the world. However, a correlation, though almost logical,

Michael E. Schudack

1999-01-01

256

Massive dissociation of gas hydrate during a Jurassic oceanic anoxic event  

PubMed

In the Jurassic period, the Early Toarcian oceanic anoxic event (about 183 million years ago) is associated with exceptionally high rates of organic-carbon burial, high palaeotemperatures and significant mass extinction. Heavy carbon-isotope compositions in rocks and fossils of this age have been linked to the global burial of organic carbon, which is isotopically light. In contrast, examples of light carbon-isotope values from marine organic matter of Early Toarcian age have been explained principally in terms of localized upwelling of bottom water enriched in 12C versus 13C (refs 1,2,5,6). Here, however, we report carbon-isotope analyses of fossil wood which demonstrate that isotopically light carbon dominated all the upper oceanic, biospheric and atmospheric carbon reservoirs, and that this occurred despite the enhanced burial of organic carbon. We propose that--as has been suggested for the Late Palaeocene thermal maximum, some 55 million years ago--the observed patterns were produced by voluminous and extremely rapid release of methane from gas hydrate contained in marine continental-margin sediments. PMID:10935632

Hesselbo; Grocke; Jenkyns; Bjerrum; Farrimond; Morgans Bell HS; Green

2000-07-27

257

Triassic-Jurassic mass extinction as trigger for the Mesozoic radiation of crocodylomorphs.  

PubMed

Pseudosuchia, one of the two main clades of Archosauria (Reptilia: Diapsida), suffered a major decline in lineage diversity during the Triassic-Jurassic (TJ) mass extinction (approx. 201 Ma). Crocodylomorpha, including living crocodilians and their extinct relatives, is the only group of pseudosuchians that survived into the Jurassic. We reassess changes in pseudosuchian morphological diversity (disparity) across this time interval, using considerably larger sample sizes than in previous analyses. Our results show that metrics of pseudosuchian disparity did not change significantly across the TJ boundary, contrasting with previous work suggesting low pseudosuchian disparity in the Early Jurassic following the TJ mass extinction. However, a significant shift in morphospace occupation between Late Triassic and Early Jurassic taxa is recognized, suggesting that the TJ extinction of many pseudosuchian lineages was followed by a major and geologically rapid adaptive radiation of crocodylomorphs. This marks the onset of the spectacularly successful evolutionary history of crocodylomorphs in Jurassic and Cretaceous ecosystems. PMID:23536443

Toljagic, Olja; Butler, Richard J

2013-06-23

258

Jurassic Park: Adventure in Learning.  

ERIC Educational Resources Information Center

Describes using the movie "Jurassic Park" as a foundation for a middle school interdisciplinary unit involving science, math, language arts, history, and geography. Suggested books and activities are presented. (PR)

Shams, Marcia; Boteler, Trina

1993-01-01

259

The Jurassic section along McElmo Canyon in southwestern Colorado  

USGS Publications Warehouse

In McElmo Canyon, Jurassic rocks are 1500-1600 ft thick. Lower Jurassic rocks of the Glen Canyon Group include (in ascending order) Wingate Sandstone, Kayenta Formation and Navajo Sandstone. Middle Jurassic rocks are represented by the San Rafael Group, which includes the Entrada Sandstone and overlying Wanakah Formation. Upper Jurassic rocks comprise the Junction Creek Sandstone overlain by the Morrison Formation. The Burro Canyon Formation, generally considered to be Lower Cretaceous, may be Late Jurassic in the McElmo Canyon area and is discussed with the Jurassic. The Upper Triassic Chinle Formation in the subsurface underlies, and the Upper Cretaceous Dakota Sandstone overlies, the Jurassic section. An unconformity is present at the base of the Glen Canyon Group (J-0), at the base of the San Rafael Group (J-2), and at the base of the Junction Creek Sandstone (J-5). Another unconformity of Cretaceous age is at the base of the Dakota Sandstone. Most of the Jurassic rocks consist of fluviatile, lacustrine and eolian deposits. The basal part of the Entrada Sandstone and the Wanakah Formation may be of marginal marine origin.

O'Sullivan, Robert B.

1997-01-01

260

The geographic and phylogenetic position of sauropod dinosaurs from the Kota formation (Early Jurassic) of India  

NASA Astrophysics Data System (ADS)

The earliest sauropods are the Late Triassic Isanosaurus from Thailand, the Early Jurassic Barapasaurus and Kotasaurus from the Kota Formation of the Pranhita-Godavari Basin of India and Vulcanodon from Zimbabwe, and a variety of Middle Jurassic genera from many localities in Gondwana and Laurasia except North America. These early sauropod genera are related, but their phylogenetic positions remain unresolved. Sauropods originated in Laurasia (Thailand and vicinity) or Pangea (broadly, Thailand, China, India), with at least three additional steps involving expansion and diversification through the Middle Jurassic.

Gillette, David D.

2003-03-01

261

Marquee Fossils  

ERIC Educational Resources Information Center

Professors of an online graduate-level paleontology class developed the concept of marquee fossils--fossils that have one or more unique characteristics that capture the attention and direct observation of students. In the classroom, Marquee fossils integrate the geology, biology, and environmental science involved in the study of fossilized

Clary, Renee; Wandersee, James

2008-01-01

262

Shallow marine carbon and oxygen isotope and elemental records indicate icehouse-greenhouse cycles during the Early Jurassic  

NASA Astrophysics Data System (ADS)

For much of the Mesozoic record there has been an inconclusive debate on the possible global significance of isotopic proxies for environmental change and of sequence stratigraphic depositional sequences. We present a carbon and oxygen isotope and elemental record for part of the Early Jurassic based on marine benthic and nektobenthic molluscs and brachiopods from the shallow marine succession of the Cleveland Basin, UK. The invertebrate isotope record is supplemented with carbon isotope data from fossil wood, which samples atmospheric carbon. New data elucidate two major global carbon isotope events, a negative excursion of ˜2‰ at the Sinemurian-Pliensbachian boundary, and a positive excursion of ˜2‰ in the Late Pliensbachian. The Sinemurian-Pliensbachian boundary event is similar to the slightly younger Toarcian Oceanic Anoxic Event and is characterized by deposition of relatively deepwater organic-rich shale. The Late Pliensbachian strata by contrast are characterized by shallow marine deposition. Oxygen isotope data imply cooling locally for both events. However, because deeper water conditions characterize the Sinemurian-Pliensbachian boundary in the Cleveland Basin the temperature drop is likely of local significance; in contrast a cool Late Pliensbachian shallow seafloor agrees with previous inference of partial icehouse conditions. Both the large-scale, long-term and small-scale, short-duration isotopic cycles occurred in concert with relative sea level changes documented previously from sequence stratigraphy. Isotope events and the sea level cycles are concluded to reflect processes of global significance, supporting the idea of an Early Jurassic in which cyclic swings from icehouse to greenhouse and super greenhouse conditions occurred at timescales from 1 to 10 Ma.

Korte, Christoph; Hesselbo, Stephen P.

2011-12-01

263

Depositional history of Jurassic rocks in the area of the Powder River basin, northeastern Wyoming and southeastern Montana  

SciTech Connect

This paper summarizes the history of clastic sedimentation in the eastern part of the middle Western Interior during the Middle and Late Jurassic. Fourteen lithostratigraphic units are discussed in relation to five separate marine inundations and six intervening erosional events.

Not Available

1992-01-01

264

Fossil Fondue  

NSDL National Science Digital Library

To understand how fossils are formed, students model the process of fossilization by making fossils using small toy figures and melted chocolate. They extend their knowledge to the many ways that engineers aid in the study of fossils, including the development of tools and technologies for determining the physical and chemical properties of fossilized organisms, and how those properties tell a story of our changing world.

Integrated Teaching And Learning Program

265

4th Grade Fossils  

NSDL National Science Digital Library

Introduction to Fossils What is a fossil What is a Fossil? Body and Trace Fossils Body and Trace Fossils Life of a Vertebrate fossil Life of a Vertebrate Fossil Finding Fossils Finding Fossils How fossils are found How fossils are formed Age of Fossils Age of Fossils in Sedimentary Rock Fossils found in Utah Fossils found in Utah Where fossils are found in Utah Where fossils are found in Utah Utah County Map Utah County Map ...

Richrigby

2010-01-26

266

Discovering Fossils: Fossil Tools & Resources  

NSDL National Science Digital Library

Fossil enthusiasts Roy Shephard and Luci Algar combined their professional skills in media and education to develop this informative and entertaining website. Designed to be educational and accessible to children, this site presents a wide variety of information about fossils. The site contains a nice collection of images and diagrams; and includes a fossils guide for beginners, information on preparing fossils, a collection of fossil myths, information on ammonites, and more. The site also contains a Games & Activities section for teachers and students, a glossary of fossil terms, a neat diagram depicting the evolution of life on our planet, and even some free fossil desktop images.

267

The Preservation of Marine Vertebrates in the Lower Oxford Clay (Jurassic) of Central England  

Microsoft Academic Search

Fossil vertebrate remains are found throughout the Lower Oxford Clay (Callovian, Middle Jurassic) in the Peterborough (Cambridgeshire) area, but occur more frequently in the Jason Zone at the base of the sequence. Five types of vertebrate preservation can be distinguished, most of which are lithologically restricted. Predation, scavenging and bacterial decomposition are responsible for the break-up of corpses. Current activity,

D. M. Martill

1985-01-01

268

Calsoyasuchus valliceps, a new crocodyliform from the Early Jurassic Kayenta Formation of Arizona  

Microsoft Academic Search

We describe a new fossil crocodyliform archosaur from the Early Jurassic Kayenta Formation of the Navajo Nation that is surprisingly derived for so ancient a specimen. High-resolution X-ray CT analysis reveals that its long snout houses an extensive system of pneumatic paranasal cavities. These are among the most distinctive features of modern crocodylians, yet the evolutionary history of this unique

Ronald S. Tykoski; Timothy B. Rowe; Richard A. Ketcham; Matthew W. Colbert

2002-01-01

269

A golden orb-weaver spider (Araneae: Nephilidae: Nephila) from the Middle Jurassic of China  

E-print Network

species from Neogene Dominican amber and one from the Eocene of Florissant, CO, USA, have been referred to the extant genus Nephila. Here, we report the largest known fossil spider, Nephila jurassica sp. nov., from Middle Jurassic (approx. 165 Ma) strata...

Selden, Paul A.; Shih, ChungKun; Ren, Dong

2011-04-20

270

Upper Jurassic of east Texas, a stratigraphic sedimentologic reevaluation  

Microsoft Academic Search

The Smackover-Haynesville of east Texas has long been modeled as a simple progradational carbonate-evaporite ramp. Recent data indicate that the conventional ramp model for this sequence should be abandoned in favor of an evolving rimmed shelf to platform model, forming in response to changes in rate of relative sea level rise during the Late Jurassic. Evidence for Smackover-Haynesville shelves include:

C. H. Moore; K. McGillis; S. Stewart; S. Wilkinson; G. Harwood

1985-01-01

271

"Fossil" Forecasting.  

ERIC Educational Resources Information Center

Presents a density study in which students calculate the density of limestone substrate to determine if the specimen contains any fossils. Explains how to make fossils and addresses national standards. (YDS)

Brody, Michael J.; deOnis, Ann

2001-01-01

272

High diversity, low disparity and small body size in plesiosaurs (Reptilia, Sauropterygia) from the Triassic-Jurassic boundary.  

PubMed

Invasion of the open ocean by tetrapods represents a major evolutionary transition that occurred independently in cetaceans, mosasauroids, chelonioids (sea turtles), ichthyosaurs and plesiosaurs. Plesiosaurian reptiles invaded pelagic ocean environments immediately following the Late Triassic extinctions. This diversification is recorded by three intensively-sampled European fossil faunas, spanning 20 million years (Ma). These provide an unparalleled opportunity to document changes in key macroevolutionary parameters associated with secondary adaptation to pelagic life in tetrapods. A comprehensive assessment focuses on the oldest fauna, from the Blue Lias Formation of Street, and nearby localities, in Somerset, UK (Earliest Jurassic: 200 Ma), identifying three new species representing two small-bodied rhomaleosaurids (Stratesaurus taylori gen et sp. nov.; Avalonnectes arturi gen. et sp. nov) and the most basal plesiosauroid, Eoplesiosaurus antiquior gen. et sp. nov. The initial radiation of plesiosaurs was characterised by high, but short-lived, diversity of an archaic clade, Rhomaleosauridae. Representatives of this initial radiation were replaced by derived, neoplesiosaurian plesiosaurs at small-medium body sizes during a more gradual accumulation of morphological disparity. This gradualistic modality suggests that adaptive radiations within tetrapod subclades are not always characterised by the initially high levels of disparity observed in the Paleozoic origins of major metazoan body plans, or in the origin of tetrapods. High rhomaleosaurid diversity immediately following the Triassic-Jurassic boundary supports the gradual model of Late Triassic extinctions, mostly predating the boundary itself. Increase in both maximum and minimum body length early in plesiosaurian history suggests a driven evolutionary trend. However, Maximum-likelihood models suggest only passive expansion into higher body size categories. PMID:22438869

Benson, Roger B J; Evans, Mark; Druckenmiller, Patrick S

2012-01-01

273

Direct chemical evidence for eumelanin pigment from the Jurassic period  

PubMed Central

Melanin is a ubiquitous biological pigment found in bacteria, fungi, plants, and animals. It has a diverse range of ecological and biochemical functions, including display, evasion, photoprotection, detoxification, and metal scavenging. To date, evidence of melanin in fossil organisms has relied entirely on indirect morphological and chemical analyses. Here, we apply direct chemical techniques to categorically demonstrate the preservation of eumelanin in two > 160 Ma Jurassic cephalopod ink sacs and to confirm its chemical similarity to the ink of the modern cephalopod, Sepia officinalis. Identification and characterization of degradation-resistant melanin may provide insights into its diverse roles in ancient organisms. PMID:22615359

Glass, Keely; Ito, Shosuke; Wilby, Philip R.; Sota, Takayuki; Nakamura, Atsushi; Bowers, C. Russell; Vinther, Jakob; Dutta, Suryendu; Summons, Roger; Briggs, Derek E. G.; Wakamatsu, Kazumasa; Simon, John D.

2012-01-01

274

Direct chemical evidence for eumelanin pigment from the Jurassic period.  

PubMed

Melanin is a ubiquitous biological pigment found in bacteria, fungi, plants, and animals. It has a diverse range of ecological and biochemical functions, including display, evasion, photoprotection, detoxification, and metal scavenging. To date, evidence of melanin in fossil organisms has relied entirely on indirect morphological and chemical analyses. Here, we apply direct chemical techniques to categorically demonstrate the preservation of eumelanin in two > 160 Ma Jurassic cephalopod ink sacs and to confirm its chemical similarity to the ink of the modern cephalopod, Sepia officinalis. Identification and characterization of degradation-resistant melanin may provide insights into its diverse roles in ancient organisms. PMID:22615359

Glass, Keely; Ito, Shosuke; Wilby, Philip R; Sota, Takayuki; Nakamura, Atsushi; Bowers, C Russell; Vinther, Jakob; Dutta, Suryendu; Summons, Roger; Briggs, Derek E G; Wakamatsu, Kazumasa; Simon, John D

2012-06-26

275

Finding Fossils  

NSDL National Science Digital Library

This OLogy activity serves as a kid-friendly how-to manual about searching for fossils. In Not Just Any Rock Will Do, kids learn that fossils "hide out" in sedimentary rock and see examples of shale and sandstone. Do's and Don'ts for Fossil Hunters gives kids practical tips and a list of fossil-hunting supplies. In Fossils You May Find, there are photos of common invertebrate, vertebrate, and plant fossils to guide kids. Paleontology Clubs and Web Sites lists resources to help kids determine where to hunt for fossils. In Keeping a Field Journal, kids are shown a sample journal entry that points out the types of information they should record.

276

Fossil humans 1 Fossil humans  

E-print Network

Fossil humans 1 Fossil humans All prehistoric skeletal remains of humans which are archeologically, anatomically modern humans. In this sense, the term "humans" is used broadly to mean all primates related of the Neanderthal speci- men in 1856. Fossil human remains have come prin- cipally from Europe, Asia, China, Java

Delson, Eric

277

Fossils 1: Fossils and Dinosaurs  

NSDL National Science Digital Library

This lesson will go beyond naming dinosaurs and give students a broad understanding of how we know about the great beasts. This lesson focuses on what we have learned and can learn from fossils. The follow-up lesson, Dinosaurs Fossils - Uncovering the Facts, explores what information can be discerned by comparing fossils to living organisms.

Science Netlinks;

2001-10-20

278

Jurassic Lake T'oo'dichi': a large alkaline, saline lake, Morrison Formation, eastern Colorado Plateau  

USGS Publications Warehouse

Recognition of alkaline, saline-lake deposits in the Morrison Formation significantly alters interpretations of depositional environments of this formation, and it also has important implications for paleoclimatic interpretation. Late Jurassic climate was apparently much more arid than had previously been thought. In fact, sedimentologic evidence suggests that the lake basin was typically dry for extended periods and enjoyed only brief wet intervals. This conclusion has important consequences for environmental interpretation of the habitat that was favorable for large herbivorous dinosaurs, which thrived in the Late Jurassic. -from Authors

Turner, C. E.; Fishman, N. S.

1991-01-01

279

Jurassic and Cretaceous Hagiastridae from the Blake-Bahama Basin /Site 5A, JOIDES Leg I/ and the Great Valley Sequence, California Coast Ranges.  

NASA Technical Reports Server (NTRS)

Description of a total of 24 new species and four genuses of Jurassic and Cretaceous Hagiastridae found in the Great Valley Sequence of the California Coast Ranges. Also described are four new species from the late Jurassic strata of the Blake-Bahama Basin. Spumellariina with a spongy meshwork is included in the superfamily Spongodiscacea Haeckel.

Pessagno, E. A., Jr.

1971-01-01

280

A Jurassic mammaliaform and the earliest mammalian evolutionary adaptations.  

PubMed

The earliest evolution of mammals and origins of mammalian features can be traced to the mammaliaforms of the Triassic and Jurassic periods that are extinct relatives to living mammals. Here we describe a new fossil from the Middle Jurassic that has a mandibular middle ear, a gradational transition of thoracolumbar vertebrae and primitive ankle features, but highly derived molars with a high crown and multiple roots that are partially fused. The upper molars have longitudinal cusp rows that occlude alternately with those of the lower molars. This specialization for masticating plants indicates that herbivory evolved among mammaliaforms, before the rise of crown mammals. The new species shares the distinctive dental features of the eleutherodontid clade, previously represented only by isolated teeth despite its extensive geographic distribution during the Jurassic. This eleutherodontid was terrestrial and had ambulatory gaits, analogous to extant terrestrial mammals such as armadillos or rock hyrax. Its fur corroborates that mammalian integument had originated well before the common ancestor of living mammals. PMID:23925238

Zhou, Chang-Fu; Wu, Shaoyuan; Martin, Thomas; Luo, Zhe-Xi

2013-08-01

281

Boron-containing organic pigments from a Jurassic red alga  

PubMed Central

Organic biomolecules that have retained their basic chemical structures over geological periods (molecular fossils) occur in a wide range of geological samples and provide valuable paleobiological, paleoenvironmental, and geochemical information not attainable from other sources. In rare cases, such compounds are even preserved with their specific functional groups and still occur within the organisms that produced them, providing direct information on the biochemical inventory of extinct organisms and their possible evolutionary relationships. Here we report the discovery of an exceptional group of boron-containing compounds, the borolithochromes, causing the distinct pink coloration of well-preserved specimens of the Jurassic red alga Solenopora jurassica. The borolithochromes are characterized as complicated spiroborates (boric acid esters) with two phenolic moieties as boron ligands, representing a unique class of fossil organic pigments. The chiroptical properties of the pigments unequivocally demonstrate a biogenic origin, at least of their ligands. However, although the borolithochromes originated from a fossil red alga, no analogy with hitherto known present-day red algal pigments was found. The occurrence of the borolithochromes or their possible diagenetic products in the fossil record may provide additional information on the classification and phylogeny of fossil calcareous algae. PMID:20974956

Wolkenstein, Klaus; Gross, Jurgen H.; Falk, Heinz

2010-01-01

282

Fossil formation  

NSDL National Science Digital Library

The National Science Education Standards Life Science Content Standard mentions that fossils indicate extinct species and contribute to an understanding of evolution and diversity. The Earth and Space Sciences Content Standard tells us they provide clues about past environments. But what is a fossil? How does it form? The processes can be complex. An understanding of fossil formation will enable accurate student conceptions of related science concepts including methods of science in geology, paleontology, and evolution.

University, Staff A.

2008-03-07

283

Fossil Find  

NSDL National Science Digital Library

In this classroom activity, middle school students simulate a "dinosaur dig." The activity opens with background information for teachers about fossils. Working in groups, students excavate fossil sites created in advance by the teacher, or other group of students, and try to reconstruct a chicken skeleton. The activity closes with a two-page student worksheet that directs students to diagram the fossil site and includes probing questions to help them decode their findings.

284

Finding Fossils  

NSDL National Science Digital Library

This activity (located on page 4 of the PDF) is a full inquiry investigation to determine the age of fossils based on where they are discovered. Groups of learners will dig for fossils embedded in a cake of multiple layers, carefully excavating each stratum and eventually preparing a chart from their notes for discussion with the group. The two main lessons from this exercise are that fossils from different layers come from different eras and that multiple interpretations of incomplete fossil evidence are possible. Relates to linked video, DragonflyTV GPS: Baby Dinosaurs.

Twin Cities Public Television, Inc.

2007-01-01

285

Middle Jurassic strata link Wallowa, Olds Ferry, and Izee terranes in the accreted Blue Mountains island arc, northeastern Oregon  

SciTech Connect

Middle Jurassic strata atop the Wallowa terrane in northeastern Oregon link the Wallowa, Izee, and Olds Ferry terranes as related elements of a single long-lived and complex oceanic feature, the Blue Mountains island arc. Middle Jurassic strata in the Wallowa terrane include a dacitic ash-flow deposit and contain fossil corals and bivalves of North American affinity. Plant fossils in fluvial sandstones support a Jurassic age and indicate a seasonal temperate climate. Corals in a transgressive sequence traditionally overlying the fluvial units are of Bajocian age and are closely related to endemic varieties of the Western Interior embayment. They are unlike Middle Jurassic corals in other Cordilleran terranes; their presence suggests that the Blue Mountains island arc first approached the North American craton at high paleolatitudes in Middle Jurassic time. The authors consider the Bajocian marine strata and underlying fluvial volcaniclastic units to be a basin-margin equivalent of the Izee terrane, a largely Middle Jurassic (Bajocian) succession of basinal volcaniclastic and volcanic rocks known to overlie the Olds Ferry and Baker terranes.

White, J.D.L. (Dalhousie Univ., Halifax, Nova Scotia (Canada)); Vallier, T. (Geological Survey, Menlo Park, CA (United States)); Stanley, G.D. Jr. (Univ. of Montana, Missoula (United States)); Ash, S.R. (Weber State Univ., Odgen, UT (United States)); White, D.L.

1992-08-01

286

Applying microCT and 3D visualization to Jurassic silicified conifer seed cones: A virtual advantage over thin-sectioning1  

PubMed Central

• Premise of the study: As an alternative to conventional thin-sectioning, which destroys fossil material, high-resolution X-ray computed tomography (also called microtomography or microCT) integrated with scientific visualization, three-dimensional (3D) image segmentation, size analysis, and computer animation is explored as a nondestructive method of imaging the internal anatomy of 150-million-year-old conifer seed cones from the Late Jurassic Morrison Formation, USA, and of recent and other fossil cones. • Methods: MicroCT was carried out on cones using a General Electric phoenix v|tome|x s 240D, and resulting projections were processed with visualization software to produce image stacks of serial single sections for two-dimensional (2D) visualization, 3D segmented reconstructions with targeted structures in color, and computer animations. • Results: If preserved in differing densities, microCT produced images of internal fossil tissues that showed important characters such as seed phyllotaxy or number of seeds per cone scale. Color segmentation of deeply embedded seeds highlighted the arrangement of seeds in spirals. MicroCT of recent cones was even more effective. • Conclusions: This is the first paper on microCT integrated with 3D segmentation and computer animation applied to silicified seed cones, which resulted in excellent 2D serial sections and segmented 3D reconstructions, revealing features requisite to cone identification and understanding of strobilus construction.

Gee, Carole T.

2013-01-01

287

Biogeochemistry of the Triassic-Jurassic Boundary  

NASA Astrophysics Data System (ADS)

New biostratigraphic and biogeochemical data are presented from Triassic-Jurassic (Tr-J) boundary sections at Kennecott Point, Queen Charlotte Islands (QCI), Canada, Muller Canyon, Nevada, USA, and Marokopa Beach, New Zealand. The New Zealand record shows two negative excursions in ?13Corg of approximately 2‰ associated with the Tr-J transition. The QCI and Nevada boundary sections show a consistent isotopic trend indicative of multiple major perturbations to the carbon cycle: one negative excursion in ?13Corg of 2‰ at the boundary and one positive excursion of 3 to 5‰ following the boundary. The post-Tr-J boundary positive excursion is especially prominent in boundary sections from QCI, where the high organic content of the black shales makes the rocks suitable for a survey of lipid biomarkers. New GC-MS data are presented from this locality, revealing changes in the distribution and abundance of alkanes, hopanes, and steranes across the Tr-J transition. Litho-, bio- and chemostratigraphy from these boundary localities do not support a single impact cause for the late Triassic extinctions, although impact events such as the Manicouagan may well have exerted significant stress on a biosphere still recovering from the Permian-Triassic mass extinction. The data support the idea of a degraded late Triassic environment persisting for millions of years and characterized by low atmospheric oxygen and high carbon dioxide associated with Central Atlantic Magmatic Province volcanism. Global warming and sea level change may have led to destabilization of seafloor methane hydrates and runaway greenhouse conditions.

Williford, K. H.; Ward, P. D.; Garrison, G. H.

2006-12-01

288

Jurassic plutons in the Desolation wilderness, northern Sierra Nevada batholith, California: A new segment in the Jurassic magmatic arc  

SciTech Connect

A 164[+-]7 Ma U-P zircon date establishes a Middle- to Late-Jurassic age for the Pyramid Peak granite and synplutonic dioritoids and hybrid rocks that comprise the Crystal Range suite, located southwest of Lake Tahoe. A Jurassic age is also assigned to the Keiths Dome quartz monzonite and the Desolation Valley and Camper Flat granodiorites (Loomis', 1983, Early Granitic Group) which are distinctly older than surrounding Cretaceous granitoids. The Keiths Dome quartz monzonite, the oldest pluton of the group, may be as old as 180 Ma and is distinguished by ductile shear zones and recrystallization textures which indicate an episode of deformation not undergone by other plutons. The Camper flat and Desolation Valley granodiorites are the youngest plutons of the group. ENE-trending microdiorite dikes filled extensional fractures, perpendicular to the direction of shortening, in all Jurassic plutons but on none of the Cretaceous bodies. Jurassic plutons may help constrain ages of metasedimentary and metavolcanic rocks and associated structures in the Mount Tallac roof pendant. The Pyramid Peak granite intrudes the Sailor Canyon Formation which bears Late Pliensbachian ammonites (Fisher, 1990), and the Keiths Dome quartz monzonite intrudes the overlying Tuttle Lake Formation and transects faults and shear zones in the pendant. Initial Sr isotope ratios for the Pyramid Peak granite range between 0.705427 and 0.706874, spanning the 0.706 value taken by some to mark the western limit of sialic lower crust. Data suggest an isotopically mixed source containing mantle and crustal components. Such an environment is not inconsistent with a passive continental margin where mafic magma invades rifted continental crust.

Sabine, C. (Desert Research Inst., Reno, NV (United States). Quaternary Sciences Center)

1993-04-01

289

The Jurassic of Svalbard, Sedimentology, Stratigraphy and Paleontology  

NASA Astrophysics Data System (ADS)

During the Mesozoic the landmass now known as Svalbard drifted from 45oN to 65oN. The average global temperature was significantly higher, disabling the formation of icecaps at the poles, resulting in a higher sea-level. At the time the location now known as Svalbard was covered by a shallow ocean and mostly marine, organic rich, black shales, interrupted by possibly deltaic sediments were deposited. These sediments are rich in invertebrate fossils. A general description of the Agardhfjellet formation, spanning the middle to upper Jurassic, was made by Dypvik in 1991. Wierzbowski (1989) described some ammonites in detail from the Kimmeridgian. It is not known if the fauna extends further up or down in the formation. Since 2004 the Museum of Natural History of Oslo has been active in Spitsbergen Svalbard. Extensive and detailed sedimentological and stratigraphic research was never conducted as the focus lay on vertebrate fossils. A detailed sedimentological analysis, description and correlation to other Jurassic Formations (such as the Kimmeridge Shales, Hekkingen Formation and draupne Formation) is essential to better understand the circumstances where the black organic-rich shales (a highly potential source rock) were deposited in and to be able to predict their occurrences. Included in this description is taxonomy, taphonomy and the stratigraphic development of invertebrate fauna to pinpoint the age of the sediments.

Koevoets, Maayke; Hammer, Øyvind

2014-05-01

290

Ediacara Fossils  

ERIC Educational Resources Information Center

Now, a research team from Virginia Tech and Nanjing Institute of Geology and Paleontology has discovered uniquely well-preserved fossil forms from 550-million-year-old rocks of the Ediacaran Period. The research appears in the Proceedings of the National Academy of Sciences. The discovery of these unusually preserved fossils reveals unprecedented…

Science Teacher, 2005

2005-01-01

291

Fossil Fuels.  

ERIC Educational Resources Information Center

This instructional unit is one of 10 developed by students on various energy-related areas that deals specifically with fossil fuels. Some topics covered are historic facts, development of fuels, history of oil production, current and future trends of the oil industry, refining fossil fuels, and environmental problems. Material in each unit may…

Crank, Ron

292

Fossil Crinoids  

NASA Astrophysics Data System (ADS)

Crinoids have graced the oceans for more than 500 million years. Among the most attractive fossils, crinoids had a key role in the ecology of marine communities through much of the fossil record, and their remains are prominent rock forming constituents of many limestones. This is the first comprehensive volume to bring together their form and function, classification, evolutionary history, occurrence, preservation and ecology. The main part of the book is devoted to assemblages of intact fossil crinoids, which are described in their geological setting in twenty-three chapters ranging from the Ordovician to the Tertiary. The final chapter deals with living sea lilies and feather stars. The volume is exquisitely illustrated with abundant photographs and line drawings of crinoids from sites around the world. This authoritative account recreates a fascinating picture of fossil crinoids for paleontologists, geologists, evolutionary and marine biologists, ecologists and amateur fossil collectors.

Hess, Hans; Ausich, William I.; Brett, Carlton E.; Simms, Michael J.

1999-10-01

293

Fossil Crinoids  

NASA Astrophysics Data System (ADS)

Crinoids have graced the oceans for more than 500 million years. Among the most attractive fossils, crinoids had a key role in the ecology of marine communities through much of the fossil record, and their remains are prominent rock forming constituents of many limestones. This is the first comprehensive volume to bring together their form and function, classification, evolutionary history, occurrence, preservation and ecology. The main part of the book is devoted to assemblages of intact fossil crinoids, which are described in their geological setting in twenty-three chapters ranging from the Ordovician to the Tertiary. The final chapter deals with living sea lilies and feather stars. The volume is exquisitely illustrated with abundant photographs and line drawings of crinoids from sites around the world. This authoritative account recreates a fascinating picture of fossil crinoids for paleontologists, geologists, evolutionary and marine biologists, ecologists and amateur fossil collectors.

Hess, Hans; Ausich, William I.; Brett, Carlton E.; Simms, Michael J.

2003-01-01

294

Fossil Fuels  

NSDL National Science Digital Library

How much does the United States depend on fossil fuels? This web page, part of a site on the future of energy, introduces students to fossil fuels as an energy source. Here students read about the uses, benefits, and limitations of fossil fuels. There is also information on how these fuels are distributed geographically and how they affect the U.S. economy through supply and demand. Thought-provoking questions afford students opportunities to reflect on what they've read. Articles about clean coal, the national energy policy, and the formation of fossil fuels, together with a fossil fuels fact sheet, are accessible from a sidebar. In addition, five PBS NewsHour links to energy-related stories are included.

Project, Iowa P.

2004-01-01

295

Salt tectonism and seismic stratigraphy of the Upper Jurassic in the Destin Dome Region, northeastern Gulf of Mexico  

E-print Network

Florida Shelf. Figure 4 shows the regional distribution of Jurassic salt in the northern Gulf of Mexico. Tectonic and Geologic Framework Most investigators (Humphris, 1979; Pilger, 1981; Klitgord et al, 1984; Buffler and Sawyer, 1985; Pindell, 1985...; Salvador, 1987) think that Gulf rifting began during the Late Triassic-Early Jurassic. Buffler and Sawyer (1985) subdivide the Gulf basin into four crustal types and show that the Mesozoic sedimentary succession, within the study area, is underlain...

MacRae, Grant

2012-06-07

296

New model of succession of Middle and Late Pennsylvanian fossil communities in north Texas, Mid-Continent, and Appalachians with implications on black shale controversy  

SciTech Connect

A new model for the succession of Pennsylvanian fossil communities, preserved in cyclothems, is proposed on the basis of more than 200 fossil localities in the Mid-Continent, Appalachians, and north Texas. Early models for Mid-Continent cyclothems placed the black shales in shallow water, with maximum transgression at the fusulinid-bearing zone in the overlying limestone. The most recent model proposed that the black phosphatic shales, which commonly occur between two subtidal carbonates, are widespread and laterally continuous over great distances and represent maximum transgression. The black phosphatic shales contain: ammonoids; inarticulate brachiopods; radiolarians; conularids; shark material and abundant and diverse conodonts. The black shales grade vertically and laterally into dark gray-black shales which contain many of the same pelagic and epipelagic forms found in the phosphatic black shales. This facies contains the deepest water benthic community. Most of these forms are immature, pyritized, and generally are preserved as molds. The dark gray-black facies grades into a medium gray shale facies which contains a mature molluscan fauna. The medium gray shale grades into a lighter gray facies, which is dominated by brachiopods, crinoids, and corals, with occasional bivalves and gastropods. (These facies are interpreted as being a moderate to shallow depth shelf community). The brachiopid-crinoid community is succeeded by shallow water communities which may have occupied shoreline, lagoonal, bay, interdeltaic, or shallow prodeltaic environments.

Boardman, D.R. II; Yancey, T.E.; Mapes, R.H.; Malinky, J.M.

1983-03-01

297

Jurassic igneous-related metallogeny of southwestern North America  

E-print Network

Jurassic igneous-related metallogeny of southwestern North America Mark D. Barton*, James D Jurassic magmatism and related hydrothermal systems formed across much of southwestern North America magmatism. Princi- pal types of Jurassic mineralized systems include: (1) porphyry, skarn, replacement

Barton, Mark D.

298

NYSGA 2010 Trip 4 -Olsen Fossil Great Lakes of the Newark Supergroup  

E-print Network

NYSGA 2010 Trip 4 - Olsen 101 Fossil Great Lakes of the Newark Supergroup ­ 30 Years Later Paul E: THE TRIASSIC-JURASSIC GREAT LAKES OF CENTRAL PANGEA This guidebook focuses of the deposits, fossils dimension comparable to the scale of the American Great Lakes or the East African Great Lakes and perhaps

Olsen, Paul E.

299

Episodic dike intrusions in the northwestern Sierra Nevada, California: Implications for multistage evolution of a Jurassic arc terrane  

SciTech Connect

In the northwestern Sierra Nevada, California, volcanic and plutonic rocks of the Smartville and Slate Creek complexes, both fragments of a Jurassic arc terrane, are tectonically juxtaposed against ophiolitic and marine rocks that represent late Paleozoic-early Mesozoic oceanic basement. This oceanic basement is intruded by Early Jurassic dikes that are coeval with hypabyssal and plutonic rocks within the Smartville and Slate Creek complexes. These dikes have geochemical characteristics reflecting a depleted and metasomatized source, as commonly observed in modern fore-arc settings and incipient volcanic arcs, and are interpreted to be the conduits for the Early Jurassic arc volcanism, which was built on and across the disrupted oceanic basement. Late Jurassic sheeted dikes intruding the Smartville complex have basaltic compositions compatible with an intra-arc or back-arc origin and indicate that a spreading event occurred within the arc in early Late Jurassic time. These interpretations support models for a complex multistage evolution via episodic magmatism and deformation within a singly ensimatic Jurassic arc terrane west of the North American continent.

Dilek, Y.; Moores, E.M. (Univ. of California, Davis (USA)); Thy, P. (NASA, Houston, TX (USA))

1991-02-01

300

Prolific Overton field gas reservoirs within large transverse oolite shoals, Upper Jurassic Haynesville, Eastern Margin East Texas basin  

Microsoft Academic Search

Late Triassic rifting along a northeast-southwest spreading center in east Texas resulted in basement highs along the eastern margin of the East Texas basin that became sites of extensive ooid shoal deposition during Late Jurassic time. Reservoirs within oolite facies at Overton field contain over 1 tcf of natural gas. These large shoals, each approximately 15 mi (24 km) long

T. E. Covington; R. G. Lighty; W. M. Ahr

1985-01-01

301

The Jurassic-early Cretaceous Ilo batholith of southern coastal Peru: geology, geochronology and geochemistry  

Microsoft Academic Search

The Ilo batholith (17°00 - 18°30 S) crops out in an area of about 20 by 100 km, along the coast of southern Peru. This batholith is emplaced into the `Chocolate` Formation of late Permian to middle Jurassic age, which consists of more than 1000 m of basaltic and andesitic lavas, with interbedded volcanic agglomerates and breccias. The Ilo Batholith

Flora Boekhout; Thierry Sempere; Richard Spikings; Urs Schaltegger

2010-01-01

302

Response to Comment on "A Jurassic ornithischian dinosaur from Siberia with both feathers and scales".  

PubMed

Lingham-Soliar questions our interpretation of integumentary structures in the Middle-Late Jurassic ornithischian dinosaur Kulindadromeus as feather-like appendages and alternatively proposes that the compound structures observed around the humerus and femur of Kulindadromeus are support fibers associated with badly degraded scales. We consider this hypothesis highly unlikely because of the taphonomy and morphology of the preserved structures. PMID:25342796

Godefroit, Pascal; Sinitsa, Sofia M; Dhouailly, Danielle; Bolotsky, Yuri L; Sizov, Alexander V; McNamara, Maria E; Benton, Michael J; Spagna, Paul

2014-10-24

303

Fossils 1: Fossils and Dinosaurs  

NSDL National Science Digital Library

In this lesson, students will understand what can be learned from fossils and in doing so, realize the difference between fact and theory. This lesson is the first of a two-part series on fossils. These lessons will go beyond naming dinosaurs and give students a broad understanding of how we know about the great beasts. They will start to acquire knowledge of the fossil record in preparation for learning about evolution and natural selection, concepts they will study in high school. This particular lesson focuses on what we have learned and can learn from fossils. In the first part, students will discuss what we know about horses. They will then do the same for a Stegosaurus. Another part of the lesson briefly covers how fossils are formed.

304

The evolution of Iberia during the Jurassic from palaeomagnetic data  

NASA Astrophysics Data System (ADS)

A revision of Jurassic palaeomagnetic data from Iberia has been carried out in order to investigate the consistency between the palaeomagnetic information and the tectonic models proposed for the western Mediterranean. Due to the presence of a widespread (but partial) remagnetization which affected most Jurassic sediments in Iberia, selection criteria have been designed to avoid completely remagnetized sites. A total of 72 sites have been considered for the palaeomagnetic discussion (35 sites from the Messejana-Plasencia dolerite dyke, 14 sedimentary sites from the Iberian Range and 23 sites from the Betic Cordillera). Three palaeopoles for Iberia have been selected (from the Iberian Massif and from the Iberian Range) for the period around 200 Ma, the Toarcian-Aalenian and the Oxfordian. Data from the Subbetic Zone (Betic Cordillera) are used to constrain the palaeolatitude of the Iberian microplate. Iberian data are in general agreement with the BC02 master curve and the reconstruction parameters used to transfer the Iberian data to Europe, but lower palaeolatitudes than predicted by BC02 master curve are observed in Iberia for the Late Jurassic. Iberia reached a maximum in palaeolatitude during the Toarcian-Aalenian (the reference point of Madrid was at about 37°), and since then, the palaeolatitude decreased (Madrid was at 22° by the Kimmeridgian). Tectonic reference models for the Western Mediterranean (Stampfli and Borel, 2002, 2004) do not fit the Iberian declinations and palaeolatitudes. New palaeogeographic reconstructions are proposed for the Hettangian-Sinemurian, the Toarcian-Aalenian and the Oxfordian.

Osete, María-Luisa; Gómez, Juan J.; Pavón-Carrasco, Fco. Javier; Villalaín, Juan J.; Palencia-Ortas, Alicia; Ruiz-Martínez, Vicente. C.; Heller, Friedrich

2011-04-01

305

Upper Jurassic depositional systems and hydrocarbon potential of southeast Mississippi  

SciTech Connect

Upper Jurassic sedimentation in southeast Mississippi was controlled by eustatic sea level fluctuations and locally modified by salt tectonism and basement structure. This study, using conventional core data and geophysical logs, indicates that a stable carbonate platform developed along the updip margin of the Mississippi interior salt basin. The basin was partially barred from the main Gulf of Mexico water mass by the Wiggins uplift, and became evaporitic during the Late Jurassic. Moldic, intercrystalline, and vuggy dolomite porosity is developed on the crests of intermediate and high-amplitude salt highs and on the Wiggins uplift. Jurassic source rocks are lower Smackover laminated lime mudstones. Migration into adjacent reservoirs postdated formation of porosity and the growth of salt anticlines, the most common trap type. A large potential Norphlet-Smackover gas play extends along the southern flank of the Wiggins uplift. Salt anticlines within the interior basin remain viable targets. Small oil discoveries should continue in stratigraphic traps, subtle salt structures, and basement blocks on the platform.

Meendsen, F.C.; Moore, C.H.; Heydari, E.; Sassen, R.

1987-09-01

306

Middle Jurassic sand reservoirs of Tazovskoe field (West Siberia)  

NASA Astrophysics Data System (ADS)

Perspectives of Tazovskoe field Jurassic strata development are associated with lithological and mineralogical characteristics of reservoirs, which are the main reserve of the region, because of the high rate of depletion of the most prolific Cenomanian gas pools. Tazovskoye field is multibedded and is unique in terms of hydrocarbon reserves. Middle Jurassic strata occur everywhere and are represented by rocks of the Tyumenskaya formation, comprising layers J2 - J5. The producing horizons are composed of sandstones, sandy siltstones, cemented by shaly-carbonate cement mass. According to laboratory data, the Jurassic reservoirs are characterized by a wide range of porosity (up to 22.5%) and mainly low permeability (up to 2 mD), except for a few samples of J3 reservoir with permeability up to 100-150 mD. Test objects were the core samples taken from 7 intervals of the well T-83 and logging data from 4 intervals of wells 73, 93 in the Tazovskoye field. Depth and core recovery from T-83 well of the Tazovskoye field are shown in Table 1. Total linear core recovery from the Jurassic strata was 79.4 m. Late Bajocian-Bathonian alluvial-lacustrine strata compose the first regressive cycle of sedimentation in the Tazovskoye field. They are represented by alternating thin sandy, siltstone-sandy, siltstone, shaly-siltstone, siltstone-shaly, and shaly rocks with coal interbeds. They include three main productive formations: J2, J3 and J4. Above in the vertical section, the Upper Jurassic rocks occur, while lower, basal strata of the Callovian stage overlay them with a distinct unconformity. In the Upper Jurassic time, the main transgression phase of the Jurassic period occurred over the whole territory of the Western Siberia. These strata are built by non-uniform alternating sandstones, siltstones and shales with coal interbeds of the continental genesis (alluvial-lacustrine); The reservoirs contain cyclites that as a rule have binary structure, less often - ternary structure: the lower element of cyclites is represented by sandy and siltstone-sandy strata formed in a channel and in a point-bar, the upper element of cyclites is represented by siltstone, siltstone-shaly, shaly, and carbonaceous-shaly strata formed in the floodplain or in lacustrine-boggy sedimentation environment; The producing strata of J2-J4 formations are characterized in general by moderate porosity (11-17%) and low permeability (1 mD); This genetic type of the Middle Jurassic reservoirs is typical throughout the Pur-Taz petroleum region, as well is possible for the Nadym-Pur petroleum region, except for the most eastern areas of Nadym, where these rocks have flysch nature, and therefore one can predict their presence in adjacent fields, where the Jurassic reservoirs are not discovered yet.Core recoveries from T83 well;

Kurasov, I. A.

2012-12-01

307

Sub-fossil beetle assemblages associated with the "mammoth fauna" in the Late Pleistocene localities of the Ural Mountains and West Siberia  

PubMed Central

Abstract The distribution of beetles at the end of the Middle Pleninglacial (=terminal Quaternary) was examined based on sub-fossil material from the Ural Mountains and Western Siberia, Russia. All relevant localities of fossil insects have similar radiocarbon dates, ranging between 33,000 and 22,000 C14 years ago. Being situated across the vast territory from the southern Ural Mountains in the South to the middle Yamal Peninsula in the North, they allow latitudinal changes in beetle assemblages of that time to be traced. These beetles lived simultaneously with mammals of the so-called “mammoth fauna” with mammoth, bison, and wooly rhinoceros, the often co-occurring mega-mammalian bones at some of the sites being evidence of this. The beetle assemblages found between 59° and 57°N appear to be the most interesting. Their bulk is referred to as a “mixed” type, one which includes a characteristic combination of arcto-boreal, boreal, steppe and polyzonal species showing no analogues among recent insect complexes. These peculiar faunas seem to have represented a particular zonal type, which disappeared since the end of the Last Glaciation to arrive here with the extinction of the mammoth biota. In contrast, on the sites lying north of 60°N, the beetle communities were similar to modern sub-arctic and arctic faunas, yet with the participation of some sub-boreal steppe components, such as Poecilus ravus Lutshnik and Carabus sibiricus Fischer-Waldheim. This information, when compared with our knowledge of synchronous insect faunas from other regions of northern Eurasia, suggests that the former distribution of beetles in this region could be accounted for both by palaeo-environmental conditions and the impact of grazing by large ruminant mammals across the so-called “mammoth savannas”. PMID:21738409

Zinovyev, Evgeniy

2011-01-01

308

Fossil Halls  

NSDL National Science Digital Library

The American Museum of Natural History is home to the world's largest collection of vertebrate fossils, totaling nearly one million specimens. This Web site offers visitors a virtual visit to the Museum's famed Fossil Halls. It features sections on Cladistics, Vertebrate Evolution, Exhibit Specimens, a collection of 19 biographies of important people in paleontology and Virtual Tours of four of the halls. There is also an elementary school teacher guide to the museum exhibit.

309

The Early Jurassic to Aalenian paleobiogeography of the Arctic realm: Implication of microbenthos (Foraminifers and Ostracodes)  

Microsoft Academic Search

Stages in evolution of the Early Jurassic to Aalenian foraminifers and ostracodes are established based on the analyzed diversity dynamics of respective microfauna associations. Evolution of foraminifers is divided in two, the Hettangian-initial early Toarcian and the late early Toarcian-Aalenian stages, while the identical first stage in evolution of ostracodes has been followed by the late early Toarcian-Callovian stage. During

B. L. Nikitenko

2008-01-01

310

The Early Jurassic to Aalenian paleobiogeography of the Arctic realm: Implication of microbenthos (Foraminifers and Ostracodes)  

Microsoft Academic Search

Stages in evolution of the Early Jurassic to Aalenian foraminifers and ostracodes are established based on the analyzed diversity\\u000a dynamics of respective microfauna associations. Evolution of foraminifers is divided in two, the Hettangian-initial early\\u000a Toarcian and the late early Toarcian-Aalenian stages, while the identical first stage in evolution of ostracodes has been\\u000a followed by the late early Toarcian-Callovian stage. During

B. L. Nikitenko

2008-01-01

311

Jurassic Park Institute: Dino Lab  

NSDL National Science Digital Library

Created as a "science-based and educationally focused program," the Jurassic Park Institute (JPI) aims to provide "kids, families, educators and scientists with the ultimate resource for dinosaur learning and fun." As would be expected from a project of Universal Studios, the JPI Dino Lab Web site is packed with cool computer animation and other multimedia features. Visitors to this site become virtual dinosaur paleontologists, interpreting discoveries and solving problems along the way. Educators can register for JPI Dino Lab's free Teacher Resources, which includes lesson plans, assessment tools, and teaching strategy tips. This site is best accessed with a high-speed connection.

312

Rulers of the Jurassic Seas  

NSDL National Science Digital Library

Available free from Scientific American's Website, this article takes a thorough and fascinating look at the marine reptiles known as Ichthyosaurs that lived during the Mesozoic Era. The text covers recent discoveries about the evolution of Ichthyosaurs from land dwelling reptiles, including limb adaptations. Highlights of the article are special sections about ichthyosaur eyes and diet, and color illustrations and diagrams. The text contains hyperlinks to related pages (Britannica.com, Tree of Life, American Cetacean Society, etc.). "Rulers of the Jurassic Seas" is a good read for students of paleontology or marine science.

Motani, Ryosuke.

2000-01-01

313

Palynological age determination for Dorcheat and Hosston Formations - Jurassic-Cretaceous boundary in northern Louisiana  

SciTech Connect

Forty-four core samples from three wells drilled into the Dorcheat and Hosston formations in northern Louisiana were examined for fossil palynomorphs. These samples were obtained from the four beds of the Dorcheat formation, and from the lower two beds of the Hosston Formation. A diverse terrestrial and marine palynoflora containing stratigraphically significant species indicates that the cored section of strata spans the Jurassic-Cretaceous boundary.

Rogers, R.

1987-09-01

314

Massive dissociation of gas hydrate during a Jurassic oceanic anoxic event  

Microsoft Academic Search

In the Jurassic period, the Early Toarcian oceanic anoxic event (about 183 million years ago) is associated with exceptionally high rates of organic-carbon burial, high palaeotemperatures and significant mass extinction. Heavy carbon-isotope compositions in rocks and fossils of this age have been linked to the global burial of organic carbon, which is isotopically light. In contrast, examples of light carbon-isotope

Stephen P. Hesselbo; Darren R. Gröcke; Hugh C. Jenkyns; Christian J. Bjerrum; Paul Farrimond; Helen S. Morgans Bell; Owen R. Green

2000-01-01

315

Two new species of Trichoceridae from the Middle Jurassic Jiulongshan Formation of Inner Mongolia, China.  

PubMed

Two new species, Eotrichocera (Archaeotrichocera) longensis sp. n. and Eotrichocera (Archaeotrichocera) amabilis sp. n. of Trichoceridae are described based on a combination of the following characters: Sc ending proximad of the forking of R2, shape of d cell and A2 rather short and bending sharply toward posterior margin. These fossil specimens were collected from the Middle Jurassic Jiulongshan Formation of Daohugou in Inner Mongolia, China. PMID:24899858

Dong, Fei; Shih, Chungkun; Ren, Dong

2014-01-01

316

A remarkable new genus of Tettigarctidae (Insecta, Hemiptera, Cicadoidea) from the Middle Jurassic of northeastern China.  

PubMed

Tianyuprosbole zhengi, a remarkable new genus and species of Tettigarctidae (Insecta, Hemiptera, Cicadoidea), is described based on a whole-bodied fossil from the Middle Jurassic of Daohugou, northeastern China. The new species possesses a tegmen similar to that of Cicadoprosbole, the type genus of Cicadoprosbolinae, and has an exceedingly expanded pronotum as the extant genus Tettigarcta. This specimen provides new insights in the evolution and taxonomy of tettigarctids. PMID:24870657

Chen, Jun; Wang, Bo; Zhang, Haichun; Wang, Xiaoli

2014-01-01

317

Upper Jurassic of east Texas, a stratigraphic sedimentologic reevaluation  

SciTech Connect

The Smackover-Haynesville of east Texas has long been modeled as a simple progradational carbonate-evaporite ramp. Recent data indicate that the conventional ramp model for this sequence should be abandoned in favor of an evolving rimmed shelf to platform model, forming in response to changes in rate of relative sea level rise during the Late Jurassic. Evidence for Smackover-Haynesville shelves include: (1) thick high-energy carbonates along the basin margin in the Smackover and throughout the Haynesville, (2) low-energy pellet-dominated lagoonal carbonates, evaporites, and evaporitic siliciclastics occurring landward of, and interfingering with, the Smackover and Haynesville basin-margin carbonate barriers, (3) deeper water, open-marine low-energy limestones with black shales seaward of the basin-margin barriers (Smackover-Gilmer undifferentiated), and (4) the Gilmer shale forms a siliciclastic wedge seaward of the Haynesville basin margin and its zero isopach defines the Kimmeridgian shelf margin. The Smackover and Haynesville seem to represent 2 distinct sedimentologic cycles, with each cycle reflecting an initial relative sea level rise during which a rimmed shelf and lagoon are developed, and a terminal sea level standstill during which the shelf evolved into a high-energy platform. Although these sedimentologic patterns seem compatible with accepted Jurassic sea level curves, they may also reflect differential basin-margin subsidence combined with variable carbonate production rates. Finally, the shelf-platform model more clearly defines future exploration strategies for Smackover-Haynesville targets in east Texas and perhaps across the Gulf of Mexico, if eustatic sea level changes were the dominant causative factor for shelf development in the Late Jurassic.

Moore, C.H.; McGillis, K.; Stewart, S.; Wilkinson, S.; Harwood, G.

1985-02-01

318

Strategies for assessing EarlyMiddle (PliensbachianAalenian) Jurassic  

E-print Network

Strategies for assessing Early�Middle (Pliensbachian�Aalenian) Jurassic cyclochronologies By Linda cyclostratigraphy of the Jurassic Period. First, Jurassic geochronology is not well constrained, due to a general in stratigraphic constraints. These problems are particularly troublesome in the Early to Middle Jurassic cyclic

319

Diversity dynamics and mass extinctions of the Early–Middle Jurassic foraminifers: A record from the Northwestern Caucasus  

Microsoft Academic Search

The Early–Middle Jurassic foraminiferal assemblages of the Northwestern Caucasus, including a total of 315 species and 68 genera, were analysed to establish the principal diversity patterns at substage level of resolution. An overall conclusion is that the number of species varied significantly in contrast to the number of genera. The most diversified were Late Sinemurian–Pliensbachian, Late Toarcian–Early Aalenian, and Late

Dmitry A. Ruban; Jaros?aw Tyszka

2005-01-01

320

The Early Eukaryotic Fossil Record  

Microsoft Academic Search

The Precambrian era records the evolution of the domain Eucarya. Although the taxonomy of fossils is often impossible to resolve\\u000a beyond the level of domain, their morphology and chemistry indicate the evolution of major biological innovations. The late\\u000a Archean record for eukaryotes is limited to trace amounts of biomarkers. Morphological evidence appears in late Paleoproterozoic\\u000a and early Mesoproterozoic (1800–1300 Ma)

Emmanuelle J. Javaux

321

Increased fire activity at the Triassic/Jurassic boundary in Greenland due to climate-driven floral change  

NASA Astrophysics Data System (ADS)

One of the largest mass extinctions of the past 600 million years (Myr) occurred 200Myr ago, at the Triassic/Jurassic boundary. The major floral and faunal turnovers have been linked to a marked increase in atmospheric carbon dioxide levels, probably resulting from massive volcanism in the Central Atlantic Magmatic Province. Future climate change predictions suggest that fire activity may increase, in part because higher global temperatures are thought to increase storminess. Here we use palaeontological reconstructions of the fossil flora from East Greenland to assess forest flammability along with records of fossil charcoal preserved in the rocks to show that fire activity increased markedly across the Triassic/Jurassic boundary. We find a fivefold increase in the abundance of fossil charcoal in the earliest Jurassic, which we attribute to a climate-driven shift from a prevalence of broad-leaved taxa to a predominantly narrow-leaved assemblage. Our fire calorimetry experiments show that narrow leaf morphologies are more flammable than broad-leaved morphologies. We suggest that the warming associated with increased atmospheric carbon dioxide levels favoured a dominance of narrow-leaved plants, which, coupled with more frequent lightening strikes, led to an increase in fire activity at the Triassic/Jurassic boundary.

Belcher, Claire M.; Mander, Luke; Rein, Guillermo; Jervis, Freddy X.; Haworth, Matthew; Hesselbo, Stephen P.; Glasspool, Ian J.; McElwain, Jennifer C.

2010-06-01

322

Plutonic rocks of Jurassic age in the Alaska-Aleutian Range batholith: chemical variation and polarity.  

USGS Publications Warehouse

Plutonic rocks of Jurassic age exposed on the Pacific side of this batholith form a compositionally continuous calc-alkaline suite that ranges from hornblende gabbro to quartz monzonite. Tonalite and quartz diorite are the dominant rock types. Trend-surface analysis of 102 samples indicates that the direction of slope of the trend is approximately normal to the Jurassic magmatic arc. K2O and SiO2 increase towards the E-SE and the other oxides towards the W-NW. If the chemical trends reflect the approximate geometry of a palaeo-subduction zone, the polarity of the Jurassic magmatic arc is to the NW, i.e. subduction was directed towards the SE. Thus the palaeo-subduction zone is on the opposite side of the arc from the position that has generally been assumed, indicating that the Jurassic plutonic rocks were not generated in response to classical Andean-type convergent plate margins. The magmatic arc may have been formed in an intra-ocean environment and subsequently has been rafted northwards and accreted to this part of the N Pacific rim during the late Mesozoic. Middle and Upper Jurassic clastics underlying Cook Inlet to the SE and derived from the magmatic arc are classified as back-arc deposits, rather than as an arc-trench gap sequence.-L.C.H.

Reed, B.I.; Miesch, A.T.; Lanphere, M.A.

1983-01-01

323

Pump-Probe Microscopic Imaging of Jurassic-Aged Eumelanin  

PubMed Central

Melanins are biological pigments found throughout the animal kingdom that have many diverse functions. Pump-probe imaging can differentiate the two kinds of melanins found in human skin, eumelanin and pheomelanin, the distributions of which are relevant to the diagnosis of melanoma. The long-term stability of the melanin pump-probe signal is central to using this technology to analyze melanin distributions in archived tissue samples to improve diagnostic procedures. This report shows that most of the pump-probe signal from eumelanin derived from a Jurassic cephalopod is essentially identical to that of eumelanin extracted from its modern counterpart, Sepia officinalis. However, additional classes of eumelanin signals found in the fossil reveal that the pump-probe signature is sensitive to iron content, which could be a valuable tool for pathologists who cannot otherwise know the microscopic distributions of iron in melanins. PMID:23847720

Simpson, Mary Jane; Glass, Keely E.; Wilson, Jesse W.; Wilby, Philip R.; Simon, John D.

2013-01-01

324

Evolution of the biosphere and fossil fuels  

Microsoft Academic Search

The effect of fundamental events in biological evolution on the scale of fossil-fuel accumulation from the historical aspect is considered. Four main stages in the establishment of the ancient biospheres are recognized: pro-, proto-, neoto-, and acmeobiospheres. The hypothesis is based on especially favorable conditions for the formation of oil and fossil fuels during late Archean and early Proterozoic time.

N. V. Lopatin

1980-01-01

325

56 SCIENCE SCOPE Fossil sharks: Learning  

E-print Network

, that particular area was cov- ered with water. Plate tectonics Scientific evidence indicates that the positions of continents have changed over geologic time as a result of plate tectonics. These Earth move- ments have Fossils tell important stories about plate tectonics. Re- lated fossils are often discovered at varied

Bermingham, Eldredge

326

Constraints on Phanerozoic paleotemperature and seawater oxygen isotope evolution from the carbonate clumped isotope compositions of Late Paleozoic marine fossils (Invited)  

NASA Astrophysics Data System (ADS)

A long-standing geoscience controversy has been the interpretation of the observed several per mil increase in the oxygen isotope compositions of marine calcites over the Phanerozoic Eon. Explanations for this trend have included decreasing seawater paleotemperatures, increasing seawater oxygen isotope values, and post-depositional calcite alteration. Carbonate clumped isotope paleothermometry is a useful geochemical tool to test these hypotheses because of its lack of dependence on the bulk isotopic composition of the water from which carbonate precipitated. This technique is increasingly applied to ancient marine invertebrate shells, which can be screened for diagenesis using chemical and microstructural approaches. After several years of clumped isotope analysis of these marine carbonates in a handful of laboratories, a long-term temperature and isotopic trend is emerging, with the results pointing to relatively invariant seawater ?18O and generally decreasing seawater temperatures through the Phanerozoic. Uncertainties remain, however, including the effects of reordering of primary clumped isotope compositions via solid-state diffusion of C and O through the mineral lattice at elevated burial temperatures over hundred million year timescales. To develop a quantitative understanding of such reordering, we present data from laboratory heating experiments of late Paleozoic brachiopod calcite. When combined with kinetic models of the reordering reaction, the results of these experiments suggest that burial temperatures less than ~120 °C allow for preservation of primary brachiopod clumped isotope compositions over geological timescales. Analyses of well-preserved Carboniferous and Permian brachiopods reinforce these results by showing that shells with apparent clumped isotope temperatures of ~150 °C are associated with deep sedimentary burial (>5 km), whereas those with putatively primary paleotemperatures in the 10-30 °C range experienced no more than ~1.5 km of burial. Consideration of the thermal history of samples is essential for identifying the possibility of clumped isotope alteration via C-O bond reordering. Our experimental results further suggest that even nascent reordering (<5-10%) is enough to measurably bias reconstructed paleotemperatures (and calculated seawater oxygen isotope compositions) to higher values. We also investigate the use of electron backscatter diffraction (EBSD), which resolves crystallographic orientation at high spatial resolution, as an alternative method for identifying sub-microstructural diagenesis in calcite. Preliminary results of EBSD on the experimental and natural Paleozoic brachiopod shells will be presented and discussed with respect to their clumped isotope compositions and the Phanerozoic record.

Henkes, G. A.; Passey, B. H.; Grossman, E. L.; Pérez-Huerta, A.; Shenton, B.; Yancey, T. E.

2013-12-01

327

Jurassic exploration trends of East Texas  

Microsoft Academic Search

This article deals with exploration and production from the Jurassic reservoirs of East Texas. The paper discussed the trapping mechanisms, structural configurations, lithologies and stratigraphic relationships. The major formations presented are the Smackover and the Haynesville (Cotton Valley).

M. W. Presly; C. H. Reed

1984-01-01

328

Jurassic exploration trends of East Texas  

SciTech Connect

This article deals with exploration and production from the Jurassic reservoirs of East Texas. The paper discussed the trapping mechanisms, structural configurations, lithologies and stratigraphic relationships. The major formations presented are the Smackover and the Haynesville (Cotton Valley).

Presly, M.W.; Reed, C.H.

1984-09-01

329

Jurassic-Neocomian biostratigraphy, North Slope, Alaska  

SciTech Connect

The foraminiferal and palynological biostratigraphy of subsurface Jurassic and Neocomian (Early Cretaceous) age strata from the North Slope were investigated to better define biostratigraphic zone boundaries and to help clarify the correlation of the stratigraphic units in the National Petroleum Reserve in Alaska (NPRA). Through use of micropaleontologic data, eight principal biostratigraphic units have been identified. The Neocomian and Jurassic strata have each been subdivided into four main units.

Mickey, M.B.; Haga, H.

1985-04-01

330

World petroleum systems with Jurassic source rocks  

SciTech Connect

Fourteen petroleum systems with Upper Jurassic source rocks contain one quarter of the world's discovered oil and gas. Eleven other systems with Lower and Middle Jurassic source rocks presently have a minor but significant amount of discovered oil and gas. The purpose of this article is to review the systems geologically, describe their location in space and time on a continental scale, estimate their relative petroleum system recovery efficiencies, and outline the effect their essential elements and processes have on their petroleum plumbing.

Klemme, H.D. (Geo Basins Ltd., Bondville, VT (United States))

1993-11-08

331

Fossil Fuels  

NSDL National Science Digital Library

The Department of Energy Web site Fossil Fuels is billed as an energy education site mainly for older kids, but can be enjoyed by adult kids as well. The site gives an introduction to energy, and then a more detailed look at the acquisition and uses of coal, oil, and gas. The good descriptions, illustrations, and animations, along with the frequent questions page and glossary of related terms, combine to give a clear and enlightening overview of the subject.

332

The Jurassic-early Cretaceous Ilo batholith of southern coastal Peru: geology, geochronology and geochemistry  

NASA Astrophysics Data System (ADS)

The Ilo batholith (17°00 - 18°30 S) crops out in an area of about 20 by 100 km, along the coast of southern Peru. This batholith is emplaced into the ‘Chocolate‘ Formation of late Permian to middle Jurassic age, which consists of more than 1000 m of basaltic and andesitic lavas, with interbedded volcanic agglomerates and breccias. The Ilo Batholith is considered to be a rarely exposed fragment of the Jurassic arc in Peru. Our aim is to reconstruct the magmatic evolution of this batholith, and place it within the context of long-lasting magma genesis along the active Andean margin since the Paleozoic. Sampling for dating and geochemical analyses was carried out along several cross sections through the batholith that were exposed by post-intrusion eastward tilting of 20-30°. Sparse previous work postulates early to middle Jurassic and partially early Cretaceous emplacement, on the basis of conventional K/Ar and 40Ar/39Ar dating methods in the Ilo area. Twenty new U-Pb zircon ages (LA-ICP-MS and CA-ID-TIMS) accompanied by geochemical data suggests the Ilo batholith formed via the amalgamation of middle Jurassic and early Cretaceous, subduction-related plutons. Preliminary Hf isotope studies reveal a primitive mantle source for middle Jurassic intrusions. Additional Sr, Nd and Hf isotope analyses are planned to further resolve the source regions of different pulses of plutonic activity. We strongly suggest that batholith emplacement was at least partly coeval with the emplacement of the late Permian to middle Jurassic Chocolate Formation, which was deposited in an extensional tectonic regime. Our age results and geochemical signature fit into the scheme of episodic emplacement of huge amounts of subduction related magmatism that is observed throughout the whole Andean event, particularly during the middle Jurassic onset of the first Andean cycle (southern Peru, northern Chile and southern Argentina). Although the exact geodynamic setting remains to be precisely defined, these events can be linked to extensional episodes during the breakup of Pangea, which commenced at 230-220 Ma along the western South American margin, with a period of rifting, and culminated in the Jurassic with arc and back-arc extension.

Boekhout, Flora; Sempere, Thierry; Spikings, Richard; Schaltegger, Urs

2010-05-01

333

Faunal turnover of marine tetrapods during the Jurassic-Cretaceous transition.  

PubMed

Marine and terrestrial animals show a mosaic of lineage extinctions and diversifications during the Jurassic-Cretaceous transition. However, despite its potential importance in shaping animal evolution, few palaeontological studies have focussed on this interval and the possible climate and biotic drivers of its faunal turnover. In consequence evolutionary patterns in most groups are poorly understood. We use a new, large morphological dataset to examine patterns of lineage diversity and disparity (variety of form) in the marine tetrapod clade Plesiosauria, and compare these patterns with those of other organisms. Although seven plesiosaurian lineages have been hypothesised as crossing the Jurassic-Cretaceous boundary, our most parsimonious topology suggests the number was only three. The robust recovery of a novel group including most Cretaceous plesiosauroids (Xenopsaria, new clade) is instrumental in this result. Substantial plesiosaurian turnover occurred during the Jurassic-Cretaceous boundary interval, including the loss of substantial pliosaurid, and cryptoclidid diversity and disparity, followed by the radiation of Xenopsaria during the Early Cretaceous. Possible physical drivers of this turnover include climatic fluctuations that influenced oceanic productivity and diversity: Late Jurassic climates were characterised by widespread global monsoonal conditions and increased nutrient flux into the opening Atlantic-Tethys, resulting in eutrophication and a highly productive, but taxonomically depauperate, plankton. Latest Jurassic and Early Cretaceous climates were more arid, resulting in oligotrophic ocean conditions and high taxonomic diversity of radiolarians, calcareous nannoplankton and possibly ammonoids. However, the observation of discordant extinction patterns in other marine tetrapod groups such as ichthyosaurs and marine crocodylomorphs suggests that clade-specific factors may have been more important than overarching extrinsic drivers of faunal turnover during the Jurassic-Cretaceous boundary interval. PMID:23581455

Benson, Roger B J; Druckenmiller, Patrick S

2014-02-01

334

Mud fossils  

USGS Publications Warehouse

At the close of the 18th century, the haze of fantasy and mysticism that tended to obscure the true nature of the Earth was being swept away. Careful studies by scientists showed that rocks had diverse origins. Some rock layers, containing clearly identifiable fossil remains of fish and other forms of aquatic animal and plant life, originally formed in the ocean. Other layers, consisting of sand grains winnowed clean by the pounding surf, obviously formed as beach deposits that marked the shorelines of ancient seas.

1997-01-01

335

Isotopic constraints on the petrogenesis of jurassic plutons, Southeastern California  

USGS Publications Warehouse

The 165 Ma Eagle Mountain intrusion is a heterogeneous, enclave-bearing, metaluminous remnant of the Cordilleran Jurassic arc that cuts regionally metamorphosed pre-Mesozoic rocks in the southeastern Mojave Desert of California. The main phase of the intrusion consists of granodiorite to tonalite host facies, diorite mixed facies, and homogeneous monzogranite facies. The host facies contains microdiorite enclaves interpreted as intermingled masses of mafic magma. Late-phase leucogranite stocks cut the main phase. Mineral equilibria indicate emplacement at ???6.5 km depth, with solidus temperatures ranging from 760??C for diorite to 700??C for felsic granodiorite. Although uniform radiogenic-isotope compositions (Sri = 0.7085, ???Ndi = -9.4) suggest derivation from a single source, no known source has the composition required. A hybrid source is proposed, consisting of various proportions of juvenile mantle and recycled lower crust. Calculations indicate that the source of the Eagle Mountain intrusion comprised >60% juvenile mantle and <40% recycled crust. On the basis of their isotopic compositions, other mafic Jurassic plutons in the region were derived from sources containing different proportions of mantle and crustal components.

Mayo, D. P.; Anderson, J. L.; Wooden, J. L.

1998-01-01

336

Mineralization of soft-part anatomy and invading microbes in the horseshoe crab Mesolimulus from the Upper Jurassic Lagerstätte of Nusplingen, Germany  

PubMed Central

A remarkable specimen of Mesolimulus from the Upper Jurassic (Kimmeridgian) of Nusplingen, Germany, preserves the musculature of the prosoma and associated microbes in three dimensions in calcium phosphate (apatite). The musculature of Mesolimulus conforms closely to that of modern horseshoe crabs. Associated with the muscles are patches of mineralized biofilm with spiral and coccoid forms. This discovery emphasizes the potential of soft-bodied fossils as a source for increasing our knowledge of the diversity of fossil microbes in particular settings. PMID:15817437

Briggs, Derek E.G; Moore, Rachel A; Shultz, Jeffrey W; Schweigert, Günter

2005-01-01

337

Dictyodoru and associated trace fossils from the Palaeozoic of Thuringia  

E-print Network

Carboniferous Bordenschiefer. Trace fossils of the Late Ordovician Hauptquarzit The Hauptquarzit is datedDictyodoru and associated trace fossils from the Palaeozoic of Thuringia MICHAEL J. BENTON Bcnton. 15, pp. 115-132. Oslo. ISSN 00?4-1164. Dicryudora occurs in the Huupryuurrif (Late Ordovician; D

Benton, Michael

338

The girdles of the oldest fossil turtle, Proterochersis robusta, and the age of the turtle crown  

PubMed Central

Background Proterochersis robusta from the Late Triassic (Middle Norian) of Germany is the oldest known fossil turtle (i.e. amniote with a fully formed turtle shell), but little is known about its anatomy. A newly prepared, historic specimen provides novel insights into the morphology of the girdles and vertebral column of this taxon and the opportunity to reassess its phylogenetic position. Results The anatomy of the pectoral girdle of P. robusta is similar to that of other primitive turtles, including the Late Triassic (Carnian) Proganochelys quenstedti, in having a vertically oriented scapula, a large coracoid foramen, a short acromion process, and bony ridges that connect the acromion process with the dorsal process, glenoid, and coracoid, and by being able to rotate along a vertical axis. The pelvic elements are expanded distally and suturally attached to the shell, but in contrast to modern pleurodiran turtles the pelvis is associated with the sacral ribs. Conclusions The primary homology of the character “sutured pelvis” is unproblematic between P. robusta and extant pleurodires. However, integration of all new observations into the most complete phylogenetic analysis that support the pleurodiran nature of P. robusta reveals that this taxon is more parsimoniously placed along the phylogenetic stem of crown Testudines. All current phylogenetic hypotheses therefore support the basal placement of this taxon, imply that the sutured pelvis of this taxon developed independently from that of pleurodires, and conclude that the age of the turtle crown is Middle Jurassic. PMID:24314094

2013-01-01

339

Parasites in the Fossil Record: A Cretaceous Fauna with Isopod-Infested Decapod Crustaceans, Infestation Patterns through Time, and a New Ichnotaxon  

PubMed Central

Parasites are common in modern ecosystems and are also known from the fossil record. One of the best preserved and easily recognisable examples of parasitism in the fossil record concerns isopod-induced swellings in the branchial chamber of marine decapod crustaceans. However, very limited quantitative data on the variability of infestation percentages at the species, genus, and family levels are available. Here we provide this type of data for a mid-Cretaceous (upper Lower Cretaceous, upper Albian) reef setting at Koskobilo, northern Spain, on the basis of 874 specimens of anomurans and brachyurans. Thirty-seven specimens (4.2%), arranged in ten species, are infested. Anomurans are more heavily infested than brachyurans, variability can be high within genera, and a relationship may exist between the number of specimens and infestation percentage per taxon, possibly suggesting host-specificity. We have also investigated quantitative patterns of infestation through geological time based on 88 infested species (25 anomurans, 55 brachyurans, seven lobsters, and one shrimp), to show that the highest number of infested species can be found in the Late Jurassic, also when corrected for the unequal duration of epochs. The same Late Jurassic peak is observed for the percentage of infested decapod species per epoch. This acme is caused entirely by infested anomurans and brachyurans. Biases (taphonomic and otherwise) and causes of variability with regard to the Koskobilo assemblage and infestation patterns through time are discussed. Finally, a new ichnogenus and -species, Kanthyloma crusta, are erected to accommodate such swellings or embedment structures (bioclaustrations). PMID:24667587

Klompmaker, Adiel A.; Artal, Pedro; van Bakel, Barry W. M.; Fraaije, Rene H. B.; Jagt, John W. M.

2014-01-01

340

Parasites in the fossil record: a Cretaceous fauna with isopod-infested decapod crustaceans, infestation patterns through time, and a new ichnotaxon.  

PubMed

Parasites are common in modern ecosystems and are also known from the fossil record. One of the best preserved and easily recognisable examples of parasitism in the fossil record concerns isopod-induced swellings in the branchial chamber of marine decapod crustaceans. However, very limited quantitative data on the variability of infestation percentages at the species, genus, and family levels are available. Here we provide this type of data for a mid-Cretaceous (upper Lower Cretaceous, upper Albian) reef setting at Koskobilo, northern Spain, on the basis of 874 specimens of anomurans and brachyurans. Thirty-seven specimens (4.2%), arranged in ten species, are infested. Anomurans are more heavily infested than brachyurans, variability can be high within genera, and a relationship may exist between the number of specimens and infestation percentage per taxon, possibly suggesting host-specificity. We have also investigated quantitative patterns of infestation through geological time based on 88 infested species (25 anomurans, 55 brachyurans, seven lobsters, and one shrimp), to show that the highest number of infested species can be found in the Late Jurassic, also when corrected for the unequal duration of epochs. The same Late Jurassic peak is observed for the percentage of infested decapod species per epoch. This acme is caused entirely by infested anomurans and brachyurans. Biases (taphonomic and otherwise) and causes of variability with regard to the Koskobilo assemblage and infestation patterns through time are discussed. Finally, a new ichnogenus and -species, Kanthyloma crusta, are erected to accommodate such swellings or embedment structures (bioclaustrations). PMID:24667587

Klompmaker, Adiël A; Artal, Pedro; van Bakel, Barry W M; Fraaije, René H B; Jagt, John W M

2014-01-01

341

Chronostratigraphy and hydrocarbon habitat associated with the Jurassic carbonates of Abu Dhabi, United Arab Emirates  

SciTech Connect

Deposition of Jurassic epeiric shelf carbonates and evaporates were controlled by epeirogenic movement and sea level fluctuations which formed an excellent combination of source rocks, reservoirs and seats in Abu Dhabi. At the end of the Triassic, a relative drop in sea level, caused by eustatic sea level lowering in conjunction with minor tectonic uplift, resulted in non-deposition or erosion. In the Toarcian, deposition of carbonates and terrigenous, clastics produced the Marrat Formation. In the mid-Aalenian, a drop in sea level eroded much of the Marrat and some of the Triassic in offshore U.A.E. The deposition of the Hamlah Formation followed, under neritic, well-oxygenated conditions. The Middle Jurassic was characterized by widespread, normal marine shelf carbonates which formed the cyclic Izhara and Araej formations (reservoirs). In the Upper Jurassic, the carbonate shelf became differentiated into a broad shelf with a kerogen-rich intrashelf basin, formed in response to a eustatic rise coupled with epeirogenic downwarping and marine flooding. The intrashelf basin fill of muddy carbonate sediments constitutes the Diyab Formation and its onshore equivalent, the Dukhan Formation (source rocks). In the late Upper Jurassic, the climate became more arid and cyclic deposition of carbonates and evaporates prevailed, forming alternating peritidal anhydrite, dolomite and limestone in the Arab Formation (reservoir). Arid conditions continued into the Tithonian, fostering the extensive anhydrite of the Hith Formation (seal) in a sabkha/lagoonal setting on the shallow peritidal platform, the final regressive supratidal stage of this major depositional cycle.

Alsharahan, A.S.; Whittle, G.L.

1995-08-01

342

TriassicJurassic boundary events: Problems, progress, possibilities 1. Problems  

E-print Network

As for most geological period boundaries, the Triassic­Jurassic (T­J) transition, 200 million years agoEditorial Triassic­Jurassic boundary events: Problems, progress, possibilities 1. Problems to reconstruct past events, a physical record of their passing is essential. Here again the Triassic­Jurassic

McRoberts, Christopher A.

343

Early Jurassic Insects from the Newark Supergroup, Northeastern  

E-print Network

13 Early Jurassic Insects from the Newark Supergroup, Northeastern United States Phillip Huber, Nicholas G. McDonald, and Paul E. Olsen F ossil insects from the Early Jurassic (Hettan- gian Jurassic (Callovian) Todilto Formation of the southwestern United States, the fauna described

Olsen, Paul E.

344

JURASSIC CYCLOSTRATIGRAPHY AND PALEONTOLOGY OF THE HARTFORD BASIN  

E-print Network

A4-1 JURASSIC CYCLOSTRATIGRAPHY AND PALEONTOLOGY OF THE HARTFORD BASIN by Paul E. Olsen and Jessica, Minnesota State University, Mankato, MN 56001 INTRODUCTION Jurassic age lacustrine strata of the Hartford and interpret the cyclicity and biofacies through most of the major Jurassic intervals in the south

Olsen, Paul E.

345

Jurassic carbonate reservoirs of the Amu Darya Basin, Uzbekistan and Turkmenistan  

SciTech Connect

The Amu Darya Basin is a world class hydrocarbon province. Current reserves estimates are 220 TCF of gas and 800 MMbbl of oil and condensate, 50% of which is reservoired in Late Jurassic carbonates. Exploration opportunities still exist in large parts of the basin which are relatively undrilled. Within the 100-600m thick carbonate sequence, reservoir facies include reefs, shelf grainstones and turbidite fares. The major seal are Kimmeridgian - Tithonian evaporates which are up to 1600m thick in the basin centre. Stratigraphic trapping is common and often enhanced by structural modifications. The reservoirs are in communication with a major gas-prone Early-Middle Jurassic source rock. Oil-prone source rocks are thought to occur in basinal sediments which are coeval with the Late Jurassic reservoirs. Carbonate sedimentation commenced during the Late Jurassic with the development of a ramp complex. This evolved into a rimmed shelf with barrier and pinnacle reefs. Several cycles of relative sea-level change (largely eustatic?) influence the carbonate ramp/shelf systems and effect the distribution of reservoir facies. Numerous empirical observations by VNIGNI scientists on carbonate successions have enabled them to develop mathematically calculated indices for facies and reservoir prediction, which have been applied successfully in the Amu Darya Basin. Reservoir quality in the limestones is strongly controlled by primary facies. Reefs and shelf grainstones display the best reservoir characteristics. Whilst many facies have good total porosity, it is only the reef and grainstone belts where connected porosity (with pore throats greater than 10um) becomes effective. Burial cements are rare. Freshwater solution and cementation has often improved or preserved primary porosity.

Shein, V.S.; Fortunatova, N.K. [VNIGNI, Moscow (Russian Federation); Neilson, J.E. [Carbonate Reservoirs Ltd., Aberdeen (United Kingdom)] [and others

1995-08-01

346

Highly specialized mammalian skulls from the Late Cretaceous of South America.  

PubMed

Dryolestoids are an extinct mammalian group belonging to the lineage leading to modern marsupials and placentals. Dryolestoids are known by teeth and jaws from the Jurassic period of North America and Europe, but they thrived in South America up to the end of the Mesozoic era and survived to the beginnings of the Cenozoic. Isolated teeth and jaws from the latest Cretaceous of South America provide mounting evidence that, at least in western Gondwana, dryolestoids developed into strongly endemic groups by the Late Cretaceous. However, the lack of pre-Late Cretaceous dryolestoid remains made study of their origin and early diversification intractable. Here we describe the first mammalian remains from the early Late Cretaceous of South America, including two partial skulls and jaws of a derived dryolestoid showing dental and cranial features unknown among any other group of Mesozoic mammals, such as single-rooted molars preceded by double-rooted premolars, combined with a very long muzzle, exceedingly long canines and evidence of highly specialized masticatory musculature. On one hand, the new mammal shares derived features of dryolestoids with forms from the Jurassic of Laurasia, whereas on the other hand, it is very specialized and highlights the endemic, diverse dryolestoid fauna from the Cretaceous of South America. Our specimens include only the second mammalian skull known for the Cretaceous of Gondwana, bridging a previous 60-million-year gap in the fossil record, and document the whole cranial morphology of a dryolestoid, revealing an unsuspected morphological and ecological diversity for non-tribosphenic mammals. PMID:22051679

Rougier, Guillermo W; Apesteguía, Sebastián; Gaetano, Leandro C

2011-11-01

347

NEW METHODS TO DOCUMENT FOSSILS FROM LITHOGRAPHIC LIMESTONES OF SOUTHERN GERMANY AND LEBANON  

Microsoft Academic Search

We present different documentation methods tested on fossil specimens from Solnhofen-type lithographic limestones (Upper Jurassic, southern Germany) and from the related deposits from the Upper Cretaceous of Lebanon. One of the principles is composite imaging. This combines image fusion, i.e., coalescing several images of the same area but at different focal planes, resulting in a single image of high depth

Carolin Haug; Joachim T. Haug; Dieter Waloszek; Andreas Maas; Roger Frattigiani; Stefan Liebau

348

Trace Fossils Paleontology  

E-print Network

Trace Fossils Paleontology Geology 331 #12;Freshwater Hardgrounds and Firmgrounds and Shoreface abundant trace fossils, Cruziana Ichnofacies, Ordovician of Wyoming #12;Zoophycos, Miss., KY. Zoophycos clues: Skolithos burrows in Aladdin Sandstone, Black Hills, SD #12;Skolithos trace fossils

Kammer, Thomas

349

Fossil energy review  

SciTech Connect

The Fossil Energy Review provides an update of key events in the Department of Energy's Fossil Energy Program. This issue contains topics relating to: clean coal technology; fossil energy research; and petroleum reserves. (JEF)

Not Available

1989-01-01

350

Paleoclimatology indicators of the Salt Wash member of the Upper Jurassic Morrison Formation near Jensen, Utah  

SciTech Connect

The Upper Jurassic Morrison Formation has yielded one of the richest floras of the so-called transitional conifers'' of the Middle Mesozoic. Recently, a silicified axis of one of these conifers was collected from the Salt Wash member in essentially the same horizon as a previously reported partial Stegosaurus skeleton. In addition, two other axes of conifers were collected in the same immediate vicinity. Paleoecological considerations are extrapolated from the coniferous flora, vertebrate fauna and associated lithologies. Techniques of paleodendrology and relationships of extant/extinct environments are compared. The paleoclimatic conditions of the transitional conifers and associated dinosaurian fossils are postulated.

Medlyn, D.A. (Utah State Univ., Logan, UT (United States). Dept. of Geology); Bilbey, S.A. (Utah Field House of Natural History State Park, Vernal, UT (United States))

1993-04-01

351

What Is a Fossil?  

NSDL National Science Digital Library

In this classroom activity, young students explore the differences between bone and trace fossils. The activity opens with background information for teachers about fossils. After describing what a fossil is in their own words, students learn that a fossil is "any evidence of life that is at least 10,000 years old." They then explore the differences between trace and bone fossils by examining pictures. The activity concludes with a student worksheet that challenges them to identify trace and bone fossils.

352

Jurassic stratigraphy of the Wiggins Arch, Mississippi  

SciTech Connect

Mobil and Shell jointly explored the Wiggins arch area in southern Mississippi from 1985 to 1991. The effort concentrated on the Jurassic Norphlet and Smackover formations. Two wells were drilled into Paleozoic crystalline rocks and one well into the Pine Hill formation. Two of these wells were located on the southern side of the Wiggins arch and provide significant data for interpreting Jurassic stratigraphy. The Mobil No. 1 U.S.A. well encountered a complete Jurassic section, but with some significantly different facies than those encountered by wells to the north. A granite wash section is the equivalent to the Frisco City formation previously only found 100 mi to the north-northeast. All 300 ft of Smackover is crystalline dolomite. The Norphlet section is entirely granite wash. The Pine Hill anhydrite is unusually thick and interpreted to be equivalent to the Louann Salt. Correlations to other wells on the Wiggins arch, particularly the Conoco No. 1 Higgins, indicate that the Jurassic can be divided into three transgressive events separated by the Norphlet/Pine Hill and Frisco City/Buckner regressive events.

Rhodes, J.A.; Maxwell, G.B. (Mobil Oil Company, Houston, TX (United States))

1993-09-01

353

Discovering the "-Ologies" on the Jurassic Coast  

ERIC Educational Resources Information Center

The Jurassic Coast is Britain's only natural World Heritage site, a tangible time-line that takes one through 185 million years of history in 95 miles of coast. It provides individuals with a world-famous educational resource and an unrivalled outdoor classroom that has played a key role in the study of earth sciences. The author is keen to ignite…

Peacock, Alan

2007-01-01

354

Jurassic evolution of the Tien-Shan  

SciTech Connect

Complex studies led to identification of three stages in Jurassic deposits. The stages reflect development periods of the studied deposits. Each stage is represented by a paleogeographic map that indicates the evolution of ancient landforms in the Tien-Shan region in time and space.

Bebeshev, I.I. [Geological Institute, Moscow (Russian Federation)

1994-09-01

355

Stratigraphic and Tectonic Evolution of the Jurassic Hazelton Trough-Bowser Basin, Northwest British Columbia, Canada  

NASA Astrophysics Data System (ADS)

The Hazelton trough--Bowser basin is a large sedimentary basin that developed on volcanic arc rocks of the Stikine terrane in northern British Columbia, Canada. Its fill mostly consists of the Lower to Middle Jurassic Hazelton Group and the Middle Jurassic to Lower Cretaceous Bowser Lake Group. Regional correlations indicate that the Hazelton Group can be divided in two distinct lithostratigraphic intervals separated in most places by an unconformity. The lower Hazelton Group (LHG) is dominated by arc-related volcanic rocks, whereas the upper Hazelton Group (UHG) contains mainly fine-grained clastic rocks and lesser bimodal rift-related volcanic rocks. Lowermost coarse-grained strata of the UHG, including the bioturbated and fossiliferous units of the Smithers Formation and the Spatisizi River Formation, record a transgressive trend consistent with thermal subsidence and relative sea-level rise. Transgression of the Stikine arc culminated with the establishment of deep-water conditions in the Late Toarcian-Early Aalenian, and deposition of the Quock Formation. Interbedded siliceous mudstone and rusty-weathered tuff of the Quock Formation are correlated throughout most of the basin, except in the Iskut River area on the northwestern margin of the basin, where contemporaneous strata of the Iskut River Formation are dominated by rift-related volcanic rocks and conglomerates. Inception of rifting in the Iskut River area constitutes an independent extensional event on Stikinia, and could be related to reorganization of tectonic plates during a protracted period of terrane accretion in the Middle Jurassic. Obduction of the Cache Creek terrane over Stikinia in early Middle Jurassic provided a new source of sediment, which led to accumulation of the Bowser Lake Group. The second pulse of subsidence observed at Todagin Mountain can be explained by sediment loading of the accommodation previously generated during extension of the Hazelton trough in Early Jurassic time.

Gagnon, Jean-Francois

356

Latest Jurassic ammonoid provinces: Paleoecological implications using a general circulation model  

SciTech Connect

The Lake Permian-early Mesozoic megacontinent Pangea was progressively fragmented by two rift systems that propagated westward out of the Tethys Sea and a third more persistent rift system that connected the Boreal and Tethys seas. By the late Tithonian, these major rift systems produced interconnected oceanic seaways that divided Pangea into four continental segments: North America, Eur-Asia, and northern and southern Gondwana. Increased rates of sea-floor spreading during the Jurassic reduced the volumetric capacity of ocean basins and produced a sea level rise through the period that culminated in the Lake Jurassic. The extensive marine shelf margins and epeiric seas hosted a widely distributed and diverse ammonoid fauna. By the early Tithonian, faunal communication existed between the northwestern Tethys Sea and the eastern Panthalassa Ocean through the proto-Gulf of Mexico. By the late Tithonian, faunal similarities indicate the opening of the proto-Indian Ocean so that northern and southern Gondwana had become separate continents. A region of the equatorial Tethys that includes most of the present Arabian Peninsular contains neuritic platform facies but lacks ammonoids. In high northern latitudes, cool to cold water faunas formed a Boreal Realm which extended westward across northern North America, Europe, and Siberia during middle and late Tithonian. Late Kimmeridgian and Tithonian ammonoid distributions when compared with Late Jurassic paleoclimate simulations show likely causal relationships with sea surface water temperatures and upwelling, and possibly shed light on the temperature limitations of ammonoids. Results from modeled seasonal sea surface temperature, sea ice distribution, precipitation-evaporation, and wind-driven upwelling permit the evaluation and quantification of paleoenvironmental factors favorable as well as pernicious for ammonoid distribution.

Ross, C.A. (Chevron, Houston, TX (United States)); Moore, G.T.; Hayashida, D.N. (Chevron Oil Field Research Co., La Habra, CA (United States))

1992-01-01

357

Lower limits of ornithischian dinosaur body size inferred from a new Upper Jurassic heterodontosaurid from North America  

PubMed Central

The extremes of dinosaur body size have long fascinated scientists. The smallest (<1 m length) known dinosaurs are carnivorous saurischian theropods, and similarly diminutive herbivorous or omnivorous ornithischians (the other major group of dinosaurs) are unknown. We report a new ornithischian dinosaur, Fruitadens haagarorum, from the Late Jurassic of western North America that rivals the smallest theropods in size. The largest specimens of Fruitadens represent young adults in their fifth year of development and are estimated at just 65–75 cm in total body length and 0.5–0.75 kg body mass. They are thus the smallest known ornithischians. Fruitadens is a late-surviving member of the basal dinosaur clade Heterodontosauridae, and is the first member of this clade to be described from North America. The craniodental anatomy and diminutive body size of Fruitadens suggest that this taxon was an ecological generalist with an omnivorous diet, thus providing new insights into morphological and palaeoecological diversity within Dinosauria. Late-surviving (Late Jurassic and Early Cretaceous) heterodontosaurids are smaller and less ecologically specialized than Early (Late Triassic and Early Jurassic) heterodontosaurids, and this ecological generalization may account in part for the remarkable 100-million-year-long longevity of the clade. PMID:19846460

Butler, Richard J.; Galton, Peter M.; Porro, Laura B.; Chiappe, Luis M.; Henderson, Donald M.; Erickson, Gregory M.

2010-01-01

358

Mechanisms for high-frequency cyclicity in the Upper Jurassic limestone of northeastern Mexico  

SciTech Connect

The 520 m of Upper Jurassic Zuloaga Limestone exposed in the Sierra de Bunuelos in southern Coahuila comprise 118 cycles of peritidal carbonate rock deposited on a gently dipping ramp. Field studies with Fischer plots and time-series analysis suggest that a Milankovitchian glacioeustasy mechanism is inadequate to describe the Zuloaga cycles. Autocyclic progradation may have been the major influence on depositional cyclicity. Depositional cycles in the Zuloaga Formation typically are a few meters thick and asymmetric with subtidal wackestone and packstone grading upward into subtidal grainstone or into intertidal stromatolites. Width of the carbonate ramp is estimated to have been about 150 km. Sedimentation rates for these peritidal carbonate environments apparently exceeded subsidence rates inasmuch as most of the carbonate platform remained near sea level during Zuloaga deposition. The area was tectonically quiescent during the late Jurassic. Autocyclic shoreline progradation is a feasible mechanism for producing the high-frequency cycles, as suggested by (1) poor correlation with predicted Milankovitch periodicity shown by time-series analysis, (2) little evidence of subaerial exposure, (3) development of complete peritidal cycles, (4) general progradational sequences within each third-order unit, and (5) absence of polar glaciation during Late Jurassic.

Johnson, C.R.; Ward, W.C. (Univ. of New Orleans, LA (United States)); Goldhammer, R.K. (Exxon Production Research, Houston, TX (United States))

1991-03-01

359

Upper Jurassic and Lower Cretaceous sedimentary sequence, Baltimore Canyon trough, US Atlantic margin  

SciTech Connect

The extent and character of Upper Jurassic and Lower Cretaceous rock units in the Baltimore Canyon Trough are revealed by geologic data from 29 exploratory wells. These data, released to the public in 1982, have been used previously to define regional rock-stratigraphic units. In this study, four detailed stratigraphic cross sections were constructed to show rock-unit correlations based on lithology and electric logs. Thin-section photomicrographs document the mineralogic composition of these units. Most of the Upper Jurassic section consists primarily of Mic Mac gray shale and siltstone with minor amounts of very fine to medium-grained quartzarenite, red-brown shale, and lignite. This interval also contains some anomalously thick sandstones and siltstones, which are generally limited to the north and have been tentatively assigned to the Mohawk unit. These sandstones are mostly medium to coarse-grained, calcite-cemented quartzarenites. Upper Jurassic Abenaki limestone as much as 2210 ft (675 m) thick was penetrated by most of the eastern wells. The limestone is mostly wackestone to grainstone, with varying amounts of oolites and fossils. Thick-bedded sandstones characterize the Lower Cretaceous Mississauga unit. These sandstones are mostly fine to medium-grained, calcite-cemented quartzarenites. The overlying Naskapi unit consists of calcareous shale. Thick sandstone beds dominate the uppermost Logan Canyon unit, which consists mostly of fine to coarse-grained, calcite-cemented quartz arenite.

Libby-French, J.

1984-12-01

360

A specialized new species of Ashicaulis (Osmundaceae, Filicales) from the Jurassic of Liaoning, NE China.  

PubMed

A new species of structurally preserved fern rhizome, Ashicaulis plumites (Osmundaceae, Filicales), is described from the Middle Jurassic Tiaojishan Formation in western Liaoning Province, NE China. The new species is characterized by a peculiar sclerenchyma mass in the petiolar vascular bundle concavity. This sclerenchyma mass varies from a linear-shape to a mushroom-like shape with a remarkable outward protuberance, which distinguishes the present new species from other Ashicaulis species. Such a protuberance is very rare among osmundaceous ferns, and should represent a unique type for sclerenchymatous tissue in the osmundaceous vascular bundle concavity. Recognition of the peculiar structure of this new fossil species enriches anatomical diversity of permineralized osmundaceous ferns, indicating that the family Osmundaceae might have experienced a remarkable diversification during the Middle Jurassic in NE China. The new species show anatomical similarities to Osmunda pluma Miller from the Palaeocene of North America. The occurrence of A. plumites in the Middle Jurassic of China provides a new clue for understanding the evolution of some members of the living subgenus Osmunda. PMID:24317753

Tian, Ning; Wang, Yong-Dong; Philippe, Marc; Zhang, Wu; Jiang, Zi-Kun; Li, Li-Qin

2014-03-01

361

ANEWSPECIES OFHEMIAUCHENIA(ARTIODACTYLA, CAMELIDAE) FROMTHE LATE BLANCAN OF FLORIDA  

E-print Network

A. Meachen1 A new species of lamine, Hemiauchenia gracilis n. sp., is present at six late Blancan fossil lamine fossils, represented by the genus Pleiolama, oc- curred in the Great Plains of North America by a lack of lamine fossils from Central America. The discovery of this new fossil lamine species helps

Meachen-Samuels, Julie

362

Petromagnetic and paleomagnetic study of Jurassic sedimentary rocks of the southeast of Russia  

NASA Astrophysics Data System (ADS)

In the present paper the new petro- and paleomagnetic data on the Jurassic terrigenous complexes of the Mesozoic sedimentary basins of the Amur River region, Trans Baikal region, and Yakutia are presented. The magnetic properties of the sedimentary rocks of coastal-marine (paleo-shelf) and lake genesis are investigated in the contemporary intracontinental riftogenic Mesozoic superimposed troughs of the Siberian and Amur plates: the Chulmansk, the Unda-Dainsk, the Sredne-Amur, the Amuro-Zeisk, and the Verkhne-Bureinsk troughs. The statistically significant differences in the magnetic (anisotropic) characteristics of continental and marine deposits were inferred. The correlation of the scalar and tensor characteristics of magnetic susceptibility anisotropy and the parameters of its linearity, which depend indirectly on the intensity of the folding, is established. The preferential directions of regional stress during the fold formation are determined based on the analysis of the distribution of the axes of the tensor ellipsoid of the magnetic susceptibility anisotropy. The Jurassic positions of the paleomagnetic pole, which are close to the Mesozoic section of the trajectory of its apparent motion for the North Chinese plate and which differ from the Jurassic poles of the Siberian plate, are defined more accurately. The intraplate rotations of geoblocks within the limits of the amalgamated to the end of the Jurassic-to the beginning of the Cretaceous terrains as a part of the Amur tectonic plate are inferred. The calculated coordinates of the paleomagnetic pole indicate the larger than the present-day difference of the latitudinal positions of the southern part of the Siberian plate, and also of the Amur and North Chinese plates in the Early-Middle Jurassic time. This can be indicative of the fact that the total width of the shallow residual basins of the Paleo-Asian Ocean, which separated the geoblocks indicated in the Early-Middle Jurassic, attained the first thousands of kilometers, and/or such a difference in the paleolatitudes reflects the total value of the shortening (crowding) of the crust during the accretion and the fold formation. The time of the completion of the accretion of the terrains of the Amur and the North-Chinese plates and their attachment to the Siberian plate is not earlier than the end of the Late Jurassic-the beginning of the Cretaceous.

Bretshtein, Yu. S.

2009-06-01

363

Correlation of the Jurassic through Oligocene Stratigraphic Units of Trinidad and Northeastern Venezuela  

SciTech Connect

The Jurassic through Oligocene stratigraphies of Trinidad and the Serrenia del Interior of eastern Venezuela exhibit many similarities because of their proximity on the passive continental margins of northeastern South America. A slightly later subsidence in eastern Venezuela, and the generally deeper-water sedimentation in Trinidad, is interpreted to be the result of a serration of the original rift margin, producing an eastern Venezuela promontory and Trinidadian re-entrant. We interpret these serrations to be the result of oblique (NW-SE) spreading of North and South America during Middle and late Jurassic time. The stratigraphies of northeastern Venezuela and Trinidad contrast in the Hauterivan-Albian interval, with dynamic shallow shelf environments prevailing in the Serrenia del Interior and deeper marine submarine-fan deposition in Trinidad. Both areas develop middle to Upper Cretaceous source rocks during a time of eustatic sea level high and widespread oceanic anoxia. 15 refs., 4 fig.

Algar, S. [Enterprise Oil, London (United Kingdom); Erikson, J.P. [Univ. of California, Davis, CA (United States)

1995-04-01

364

Deductions from Fossil Preservtion  

NSDL National Science Digital Library

Students will view fossils, sometimes with supporting illustrations, and answer questions about them via deductive reasoning. The exercise is highly interactive, with the instructor providing hints and helpful questions. The questions concern ways in which fossil preservation reveals information about things like what kind of organism the fossil represents, how that organism lived, and how the fossil came into being.

Stanley, Steven

365

Fossils, Rocks, and Time  

NSDL National Science Digital Library

This on-line book, published by the United States Geological Survey (USGS), discusses the use of fossils in determining the age of rocks. The publication covers how to place events in correct temporal order, a description of the geologic time scale, the use of fossils to indicate rock ages, the law of fossil succession, index fossils, and radioactive dating.

Edwards, Lucy E.; Pojeta Jr., John

1997-06-26

366

Bennettitales from the Grisethorpe Bed (Middle Jurassic) at Cayton Bay, Yorkshire, UK.  

PubMed

Middle Jurassic fossil plants from the Grisethorpe Bed at Cayton Bay and Grisethorpe Bay, Yorkshire, UK, are preserved in a soft claystone, and plant mesofossils recovered by sieving reveal excellent details of external structure. Studies of these mesofossils complement previous work on macrofossils from the Grisethorpe Bed and allow the plant fossils in this classic flora to be studied in a similar way to those preserved in Cretaceous mesofloras. Bennettitales, a key group in discussions of how angiosperms may be related to other seed plants, are especially well represented among mesofossils from the Grisethorpe Bed. Abundant bennettitalean leaves, scale leaves, and fragments of pollen and ovulate organs provide new information on these extinct plants. In particular, a specimen of Williamsoniella coronata (presumed aborted) shows only weak differentiation between interseminal scales and ovules and provides further evidence of homology between these structures. PMID:21628189

Crane, Peter R; Herendeen, Patrick S

2009-01-01

367

Deep burial dolomitization driven by plate collision: Evidence from strontium-isotopes of Jurassic Arab IV dolomites from offshore Qatar  

SciTech Connect

The use of strontium-isotope ratios of dolomites to constrain timing and mechanism of diagenesis has been investigated on Jurassic Arab IV dolomites from offshore Qatar. Reservoir quality is determined by two types of dolomites, which were differentiated geochemically (cathodoluminescence, fluid inclusions, and carbon and oxygen stable isotopes): (1) stratigraphically concordant sucrosic dolomites with high porosity formed during early near-surface diagenesis (Jurassic) and (2) stratigraphically discordant cylindrical bodies of massive, porosity-destroying dolomites formed late during deep burial diagenesis (Eocene-Pliocene). Detailed Sr-isotope analysis of dolomites from the Arab IV confirms an Early Jurassic age of the sucrosic, high porosity dolomites ({sup 87}Sr/{sup 86}SR = 0.70707 for NBS 987 = 0.71024) with magnesium and strontium being derived from Jurassic seawater. Late Tertiary compressional orogeny of the Zagros belt to the north is proposed to have caused large-scale squeezing of fluids from the pore system of sedimentary rocks. A regional deep fluid flow system developed dissolving infra-Cambrian evaporites upflow and causing large-scale deep burial dolomitization downflow.

Vahrenkamp, V.C.; Taylor, S.R. (Shell Research, Rijswijk (Netherlands))

1991-03-01

368

Multifractal and white noise evolutionary dynamics in Jurassic Cretaceous Ammonoidea  

NASA Astrophysics Data System (ADS)

For more than a decade there has been interdisciplinary debate on whether fossil origination and extinction time series show evidence of self-organized criticality (SOC) or some other, more complex hierarchical structure. Analyses of a new data set of Jurassic and Cretaceous ammonoid genera demonstrate that these taxonomic subgroups do not reproduce the patterns seen in larger data sets that pool disparate taxa. Rather, originations and extinctions in these ammonoids show no evidence of SOC, limited evidence for a hierarchical multifractal pattern, and, at least within the suborder Ammonitina, evidence consistent with a white noise signal. Although a white noise pattern has been identified previously in an ammonoid family diversity time series, the significance of such a result for ammonoid genus originations and extinctions is discussed here for the first time. This white noise pattern indicates that processes acting on short time scales (less than a few million years) dominate the Ammonitina origination and extinction records, producing a nonhierarchical diversity dynamic. Because origination events in one interval do not appear to trigger originations in subsequent intervals, ammonite evolutionary radiations were likely to be extremely rapid and driven by physical rather than biological opportunities for diversification.

Yacobucci, Margaret M.

2005-02-01

369

Extreme adaptations for aquatic ectoparasitism in a Jurassic fly larva  

PubMed Central

The reconstruction of ancient insect ectoparasitism is challenging, mostly because of the extreme scarcity of fossils with obvious ectoparasitic features such as sucking-piercing mouthparts and specialized attachment organs. Here we describe a bizarre fly larva (Diptera), Qiyia jurassica gen. et sp. nov., from the Jurassic of China, that represents a stem group of the tabanomorph family Athericidae. Q. jurassica exhibits adaptations to an aquatic habitat. More importantly, it preserves an unusual combination of features including a thoracic sucker with six radial ridges, unique in insects, piercing-sucking mouthparts for fluid feeding, and crocheted ventral prolegs with upward directed bristles for anchoring and movement while submerged. We demonstrate that Q. jurassica was an aquatic ectoparasitic insect, probably feeding on the blood of salamanders. The finding reveals an extreme morphological specialization of fly larvae, and broadens our understanding of the diversity of ectoparasitism in Mesozoic insects. DOI: http://dx.doi.org/10.7554/eLife.02844.001 PMID:24963142

Chen, Jun; Wang, Bo; Engel, Michael S; Wappler, Torsten; Jarzembowski, Edmund A; Zhang, Haichun; Wang, Xiaoli; Zheng, Xiaoting; Rust, Jes

2014-01-01

370

Extreme adaptations for aquatic ectoparasitism in a Jurassic fly larva.  

PubMed

The reconstruction of ancient insect ectoparasitism is challenging, mostly because of the extreme scarcity of fossils with obvious ectoparasitic features such as sucking-piercing mouthparts and specialized attachment organs. Here we describe a bizarre fly larva (Diptera), Qiyia jurassica gen. et sp. nov., from the Jurassic of China, that represents a stem group of the tabanomorph family Athericidae. Q. jurassica exhibits adaptations to an aquatic habitat. More importantly, it preserves an unusual combination of features including a thoracic sucker with six radial ridges, unique in insects, piercing-sucking mouthparts for fluid feeding, and crocheted ventral prolegs with upward directed bristles for anchoring and movement while submerged. We demonstrate that Q. jurassica was an aquatic ectoparasitic insect, probably feeding on the blood of salamanders. The finding reveals an extreme morphological specialization of fly larvae, and broadens our understanding of the diversity of ectoparasitism in Mesozoic insects.DOI: http://dx.doi.org/10.7554/eLife.02844.001. PMID:24963142

Chen, Jun; Wang, Bo; Engel, Michael S; Wappler, Torsten; Jarzembowski, Edmund A; Zhang, Haichun; Wang, Xiaoli; Zheng, Xiaoting; Rust, Jes

2014-01-01

371

Major adaptive radiation in neritopsine gastropods estimated from 28S rRNA sequences and fossil records.  

PubMed Central

A well-supported phylogeny of the Neritopsina, a gastropod superorder archaic in origin, radiated ecologically and diverse in morphology, is reconstructed based on partial 28S rRNA sequences. The result (Neritopsidae (Hydrocenidae (Helicinidae + Neritiliidae) (Neritidae + Phenacolepadidae))) is highly congruent with the fossil records and the character distribution of reproductive tracts in extant taxa. We suggest that the Neritopsina originated in subtidal shallow waters, invaded the land and became fully terrestrial at least three times in different clades, by the extinct Dawsonellidae in the Late Palaeozoic and by the Helicinidae and Hydrocenidae in the Mesozoic. Invasion of fresh- and brackish waters is prevalent among the Neritopsina as the Jurassic and freshwater ancestory is most probable for helicinids. The Phenacolepadidae, a group exclusively inhabiting dysoxic environments, colonized deep-sea hydrothermal vents and seeps in the Late Cretaceous or Early Cenozoic. Submarine caves have served as refuges for the archaic Neritopsidae since the Early to Middle Cenozoic, and the marine neritopsine slug Titiscania represents a highly specialized but relatively recent offshoot of this family. The Neritiliidae is another clade to be found utilizing submarine caves as shelter by the Oligocene; once adapted to the completely dark environment, but some neritiliids have immigrated to surface freshwater habitats. PMID:12495489

Kano, Yasunori; Chiba, Satoshi; Kase, Tomoki

2002-01-01

372

24/01/13 21:04New dinosaur fossil challenges bird evolution theory Page 1 of 2http://www.sciencedaily.com/releases/2013/01/130124091532.htm  

E-print Network

Pterosaur Jan. 24, 2013 -- The discovery of a new bird-like dinosaur from the Jurassic period challenges ago. Recent discoveries of feathered dinosaurs from the older Middle-Late Jurassic period have of dinosaurs called theropods from the Early Cretaceous period of Earth's history, around 120-130 million years

Claeys, Philippe

373

Jurassic Cordilleran dike swarm-shear zones: Implications for the Nevadan orogeny and North American plate motion  

SciTech Connect

A cogenetic and coeval tonalitic and mafic dike swarm has been identified within a southern fragment (the Owens Mountain area) of the western Foothills terrane (California). The dikes were mylonitized and transposed (rotated into subparallel orientation) during emplacement, from 155 to 148 Ma (U-Pb zircon data), which coincides in time with the Nevadan orogeny. Steeply southeast-plunging fold axes and S-fold geometries indicate a sinistral-sense of shear, possibly with some dip-slip motion as well. This shear zone may be the southern and possibly deeper extension of the Bear Mountains fault zone. This and other Late Jurassic Cordilleran dike swarms record a complex pattern of sinistral-sense transtension-transpression that developed at the apparent-polar-wander J2 cusp ([approximately] 150 Ma) and during subsequent, rapid, northwestward acceleration of North America. The Late Jurassic Nevadan orogeny is a manifestation of these dramatic changes in magnitude and direction of North American motion.

Wolf, M.B.; Saleeby, J.B. (California Inst. of Technology, Pasadena, CA (United States))

1992-08-01

374

A New Sauropodomorph Dinosaur from the Early Jurassic of Patagonia and the Origin and Evolution of the Sauropod-type Sacrum  

Microsoft Academic Search

BackgroundThe origin of sauropod dinosaurs is one of the major landmarks of dinosaur evolution but is still poorly understood. This drastic transformation involved major skeletal modifications, including a shift from the small and gracile condition of primitive sauropodomorphs to the gigantic and quadrupedal condition of sauropods. Recent findings in the Late Triassic–Early Jurassic of Gondwana provide critical evidence to understand

Diego Pol; Alberto Garrido; Ignacio A. Cerda; Andrew Allen Farke

2011-01-01

375

Preliminary interpretations of syn- and posttectonic palaeomagnetism of Jurassic sediments from Velebit Mts (Karst Dinarides, Croatia)  

NASA Astrophysics Data System (ADS)

Velebit Mts, a part of the Adria Microplate, belonged to a NE margin of Gondwana during the Carboniferous and Permian. While Permian is characterised by clastics, post-Permian sedimentation is dominated by a thick sequence of carbonate rocks. Today, the entire sequence, representing a stratigraphic range from Carboniferous to Recent, is in places more than 10,000 m thick. The Early to Late Jurrasic deposits (limestones in seven sites, reduction spots' limestones in one site and mudstones in one site) along the transect in Mali Halan in the southern part of the Velebit Mt. were studied using palaeomagnetic and rock magnetic measurements. Strata in the whole transect dips moderately to SW. Magnetic susceptibility of diamagnetic carbonates is not affected by heating up to 400-500°C. SIRM(T) experiments revealed low temperature (Tub<400°C) Ti poor magnetite and some hematite phase in fresh samples. Heating in air results in excessive growth of new magnetite phase above 600°C. Thermal and AF treatment were performed and were more successful for the Lower Jurassic sites with stronger NRM. It resulted in separation of two ChRM components: "L" with Tub up to 200-250°C and "M" with Tub up to 400-475°C or two coercivity spectra (very soft and harder) in most successfully demagnetized samples. In some samples only soft/LT component was recorded. "M" component for the Lower and Middle Jurassic sites (345/30 in situ) correlates well with results of Marton (2008) for Early Jurassic grainstones in the same area. The tilt corrected data for "M" component fall close to Middle Jurassic segment for APWP for Africa. However site means for " M" component are distributed along the small circle with subhorizontal WNW trending axis. That may be interpreted as pre- to syntectonic remenance recorded during the regional folding. Such mechanism is consistent with paleomagnetic results for remagnetized Permian clastic sediments in Velebit Mts. (Crne Grede and Kosna localities, Lewandowski et al., 2012, AGU Fall Meeting, GP21A-1136). "L" component (of lower accuracy) for Lower/Middle Jurassic sites (in situ) falls close to the Tertiary segment of APWP for Africa as well indicating its post-tectonic secondary origin. For Upper Jurassic sites with lower NRM intensity "L" component seems to be post-tectonic but results for "M" component need to be yet discussed. AMS results for sites are not consistent between sites due to varying contribution of ferro- and diamagnetic phases to magnetic susceptibility in each site.

Werner, Tomasz; Lewandowski, Marek; Vlahovi?, Igor; Veli?, Ivo; Sidorczuk, Magdalena

2013-04-01

376

Upper Jurassic carbonate/evaporite shelf, south Alabama and west Florida  

SciTech Connect

The association of Upper Jurassic carbonates and evaporites in south Alabama and west Florida defines a brining upward and inward sequence that is indicative of deposition on an increasingly evaporitic marine shelf. Structural features that bound this evaporitic shelf were the Pensacola arch, the South Mississippi platform, and the State Line flexure. Paleo-drainage of the surrounding highlands also affected shelf salinities as fresh waters were funneled into the Covington and Manila Embayments. During the Late Jurassic, marine carbonates and evaporites of the Smackover and Lower Haynesville (Buckner) Formations were deposited over Middle Jurassic Norphlet clastics that accumulated in arid continental and marginal-marine environments. Initially, Smackover carbonate deposition was pervasive across the shallow shelf. Later, as a result of increasing water salinities, contemporaneous precipitation of central-shelf evaporites and basin-edge carbonates occurred. Maximum restriction of the basin and the culmination of subaqueous deposition resulted in the formation of a basin-wide lower Haynesville salt unit. The overlying upper Haynesville strata represents a shift to subaerial environments. Application of a shelf-basin evaporite model explains the spatial and temporal lithologic relationships observed within the study area. Onlap of evaporites over porous carbonates, due to brining-upward processes, suggest that large-scale stratigraphic traps exist within the Smackover Formation in a sparsely explored part of the basin.

Moore, B.R.

1986-05-01

377

Subsidence and sedimentation on Jurassic passive continental margin, southern Alps, Italy  

SciTech Connect

The southern Alps of Italy preserve a tectonically intact array of Jurassic facies that record the evolution of a part of the margin of the Apulian plate from its ancestrial beginnings in a complex of Permian and Triassic rifted continental basins through the initial stages of breakup and stepwise foundering of a carbonate platform. Breakup was accompanied first by the rapid accumulation of thick prisms of carbonate turbidites in newly formed fault troughs. Then, as the new Ligurian oceanic basin began to open farther west and, as subsidence gradually slowed, accumulation of a succession of slowly deposited biogenous pelagic sediments recorded not only the increasing depths of the seafloor but also fluctuations in oceanographic conditions of fertility, carbonate dissolution levels, and the strength of bottom currents. Estimates of the history of seafloor depths, based on a simple subsidence law of the form Subsidence = K(Age) /sup 1/2/, provide a basis for the construction of a set of curves showing the changing depths of significant carbonate dissolution surfaces during the Jurassic in this region. The rapid 1-km deepening of the compensation depth for calcite during the Late Jurassic may be due to a change in regional oceanic vertical circulation patterns from upwelling (fertile, silica-rich, carbonate dissolving) to downwelling (less fertile, silica-poor, carbonate preserving).

Winterer, E.L. (Scripps Institution of Oceanography, La Jolla, CA); Bosellini, A.

1981-03-01

378

Jurassic through Oligocene pre-basin stratigraphy in the Santa Maria basin area, California  

SciTech Connect

Compilation from published records of 30 pre-Miocene stratigraphic columns in the Santa Maria basin area of California (west of the Sur-Nacimiento fault and north of the Santa Ynez fault) reveals two basement units and 22 overlying sedimentary units. This article displays the stratigraphic columns and includes descriptions and environmental interpretations of the 24 rock units. The basement rocks include an Upper Jurassic ophiolite sequence and the Lower Jurassic through Upper Cretaceous Franciscan Complex. Most of the 22 sedimentary units were deposited along a subduction-type margin prior to development of the late Tertiary Santa Maria basin. Overlying and generally in fault contact with the basement rocks are four Upper Jurassic through Lower Cretaceous units that were deposited in basin plain and out continental margin environments. Unconformably overlying these units are eight Upper Cretaceous units that were deposited in a wide range of environments that ranged from trench, slope, and submarine fan up through shelf and nonmarine fluvial environments. Lower Tertiary units onlap unconformably onto the Cretaceous rocks and were deposited only in the southernmost part of the area. These rocks include lower Eocene basin plain and outer submarine fan deposits; middle Eocene mid-fan and slope deposits; upper Eocene inner fan, shelf, shoreface, and foreshore deposits; and Oligocene shoreface, foreshore, and nonmarine fluvial deposits.

Fritsche, A.E. (California State Univ., Northridge, CA (United States)); Yamashiro, D.A. (Groundwater Technology, Inc., Tempe, AZ (United States))

1991-02-01

379

Reconstruction of Jurassic paleogeography of part of southwestern North America: Some relevant factors  

SciTech Connect

A tectonic restoration has been initiated with the objective of reconstructing the paleogeography of the middle Jurassic volcanic and plutonic belt in part of southwestern North America west and southwest of the Colorado Plateau. Consideration of displacements of stratigraphic or tectonostratigraphic elements related to a structure or a system of structures include: (1) strike-slip translation along faults of the San Andreas system, especially those affecting rocks of the western Mojave desert region; (2) tertiary extensions west of the perimeter of the Colorado Plateau; (3) cretaceous contraction recorded by supracrustal rocks; (4) cretaceous lateral displacement, specifically as recorded by the Mojave-Snowy Lake fault; and (5) Late Jurassic lateral displacement along the Mojave-Sonora megashear. Cretaceous and Jurassic magmatic rocks are assumed to have formed about zones of subduction near the margins of converging plates. These rocks generally form crudely linear bands which may be used to monitor regional translations. Other linear elements useful in recording regional strain are facies lines and terrane boundaries, especially those related to steep lateral faults.

Anderson, T.H.; Kohn, M. (Univ. of Pittsburgh, PA (United States). Dept. of Geology and Planetary Science)

1993-04-01

380

Position of the Triassic-Jurassic boundary and timing of the end-Triassic extinctions on land: Data from the Moenave Formation on the southern Colorado Plateau, USA  

USGS Publications Warehouse

Strata of the Moenave Formation on and adjacent to the southern Colorado Plateau in Utah-Arizona, U.S.A., represent one of the best known and most stratigraphically continuous, complete and fossiliferous terrestrial sections across the Triassic-Jurassic boundary. We present a synthesis of new biostratigraphic and magnetostratigraphic data collected from across the Moenave Formation outcrop belt, which extends from the St. George area in southwestern Utah to the Tuba City area in northern Arizona. These data include palynomorphs, conchostracans and vertebrate fossils (including footprints) and a composite polarity record based on four overlapping magnetostratigraphic sections. Placement of the Triassic-Jurassic boundary in strata of the Moenave Formation has long been imprecise and debatable, but these new data (especially the conchostracans) allow us to place the Triassic-Jurassic boundary relatively precisely in the middle part of the Whitmore Point Member of the Moenave Formation, stratigraphically well above the highest occurrence of crurotarsan body fossils or footprints. Correlation to marine sections based on this placement indicates that major terrestrial vertebrate extinctions preceded marine extinctions across the Triassic-Jurassic boundary and therefore were likely unrelated to the Central Atlantic Magmatic Province (CAMP) volcanism. ?? 2011 Elsevier B.V.

Lucas, S. G.; Tanner, L. H.; Donohoo-Hurley, L. L.; Geissman, J. W.; Kozur, H. W.; Heckert, A. B.; Weems, R. E.

2011-01-01

381

Jurassic thrust burial in the Funeral Mountains of the Sevier retroarc: Linking P-T paths and Lu-Hf garnet geochronology  

NASA Astrophysics Data System (ADS)

Late Jurassic to early Cenozoic eastward subduction of the Farallon plate beneath the western margin of the North American plate led to development of the classic elements of the noncollisional two-sided Cordilleran orogen of the western US. These include from west to east, the Franciscan accretionary complex, Great Valley forearc basin, Sierran magmatic arc, and the retroarc Sevier orogenic wedge, including its metamorphic hinterland. Crustal shortening and mountain building during this noncollisional orogeny are thought to have resulted from coupling at the interface between the eastward underflowing Farallon plate and the westward moving North America plate. While the timing of Sierran arc magmatism, Great Valley forearc basin sedimentation, and Franciscan trench sedimentation and subduction metamorphism are increasingly well understood, our understanding of the timing of episodic contractional deformation in the retroarc region remains incomplete, in particular for the metamorphic hinterland. This has limited our ability to link forearc, arc, and retroarc processes, and to differentiate retroarc deformation events related to noncollisional orogenesis from shortening due to older collisional events in the late Middle to early Late Jurassic. The influence of collisional events in the forearc region -- including collision of exotic and/or fringing arcs, ridge collision, or subduction termination and inception -- on deformation in the retroarc region may be under appreciated. Lu-Hf dating and P-T path determination of prograde garnet growth, from the hinterland of the Sevier orogen in the Funeral Mountains of southeastern California, document late Middle to early Late Jurassic thrust burial; importantly, this shortening predates development of the Franciscan accretionary wedge and sedimentation in the Great Valley forearc basin. Lu-Hf garnet geochronology of middle greenschist facies pelitic schist of the Johnnie Formation of the southeastern Funeral Mountains core complex yields a 5-point garnet and whole rock isochron age of 162.1 ± 5.8 Ma (2?). Composite PT paths determined from growth-zoned garnets from the same sample show a nearly isothermal pressure increase of ~2 kbar at ~490°C, suggesting thrust burial at 162.1 ± 5.8 Ma. Subjacent chloritoid schist and marble yield muscovite argon-argon plateau ages of 152.6 ± 1.4 Ma and 146.0 ±1.1 Ma, respectively, documenting post-burial cooling in the Late Jurassic. Recognition of Late Jurassic tectonic burial in the Death Valley region suggests that the spatial distinction between "Sevier" and western older Jurassic deformation provinces becomes obscured to the south as the magmatic arc and the miogeoclinal hinge line converge. Furthermore, collision-driven shortening may be more important than currently recognized for the Jurassic tectonics of western North America, raising caution in assigning deformation to the noncollisional Sevier orogeny.

Wells, M. L.; Hoisch, T. D.; Beyene, M.; Vervoort, J. D.

2011-12-01

382

Transitional Tetrapod Fossil  

NSDL National Science Digital Library

In this video segment from NOVA: Judgment Day: Intelligent Design on Trial, learn about the discovery of a well-preserved transitional fossil and how such transitional fossils support the theory of evolution.

Foundation, Wgbh E.

2007-11-01

383

Mass Extinctions in the Marine Fossil Record  

Microsoft Academic Search

A new compilation of fossil data on invertebrate and vertebrate families indicates that four mass extinctions in the marine realm are statistically distinct from background extinction levels. These four occurred late in the Ordovician, Permian, Triassic, and Cretaceous periods. A fifth extinction event in the Devonian stands out from the background but is not statistically significant in these data. Background

David M. Raup; J. John Sepkoski

1982-01-01

384

Fun with Fossils  

NSDL National Science Digital Library

Fossils provide a valuable record of the plant and animal life and environmental conditions from millions, even billions of years ago. In this lesson, students create their own fossils, and then use multimedia resources to learn how real fossils form and what scientists can learn from them. They should understand that fossils provide evidence of plants and animals that lived long ago, as well as the environmental conditions at that time. Instructions, a materials list, and links to multimedia resources are provided.

2005-01-01

385

Adaptations for marine habitat and the effect of Triassic and Jurassic predator pressure on development of decompression syndrome in ichthyosaurs  

NASA Astrophysics Data System (ADS)

Decompression syndrome (caisson disease or the "the bends") resulting in avascular necrosis has been documented in mosasaurs, sauropterygians, ichthyosaurs, and turtles from the Middle Jurassic to Late Cretaceous, but it was unclear that this disease occurred as far back as the Triassic. We have examined a large Triassic sample of ichthyosaurs and compared it with an equally large post-Triassic sample. Avascular necrosis was observed in over 15 % of Late Middle Jurassic to Cretaceous ichthyosaurs with the highest occurrence (18 %) in the Early Cretaceous, but was rare or absent in geologically older specimens. Triassic reptiles that dive were either physiologically protected, or rapid changes of their position in the water column rare and insignificant enough to prevent being recorded in the skeleton. Emergency surfacing due to a threat from an underwater predator may be the most important cause of avascular necrosis for air-breathing divers, with relative frequency of such events documented in the skeleton. Diving in the Triassic appears to have been a "leisurely" behavior until the evolution of large predators in the Late Jurassic that forced sudden depth alterations contributed to a higher occurrence of bends.

Rothschild, B. M.; Xiaoting, Z.; Martin, L. D.

2012-06-01

386

Face-to-Fossil  

NSDL National Science Digital Library

This Web article is part of OLogy, where kids can collect virtual trading cards and create projects with them. Here they meet Deena Soris, who interviews the fossil of a Protoceratops. The more-than-20 questions answered by this dinosaur fossil cover topics such as what were you like when you were alive and how did you become a fossil.

387

The Primate Fossil Record  

Microsoft Academic Search

The Primate Fossil Record is a profusely illustrated, up-to-date, and comprehensive treatment of primate paleontology that captures the complete history of the discovery and interpretation of primate fossils. Each chapter emphasizes three key components of the record of primate evolution: history of discovery, taxonomy of the fossils, and evolution of the adaptive radiations they represent. The volume objectively summarizes the

Walter Carl Hartwig

2002-01-01

388

Is It a Fossil?  

NSDL National Science Digital Library

This formative assessment item is used to uncover students' ideas about fossils before a lesson has begun. Students will determine whether examples are fossils, and what sort of inferences can be made about prior environments because of fossils. This probe is aligned with the National Science Education Standards. Resources are provided along with instructional suggestions.

Fries-Gaither, Jessica

389

Picture Matching Fossils  

NSDL National Science Digital Library

Teaching the students how to picture match fossils and to use the Treatise to find more information. Students are given a wide range of fossils to look at and appropriate material to match their fossil to an image which gives the genus and species name. With that information, the students turn to the Treatise of Invertebrate Paleontology to find upper level taxonomic names.

Rhenberg, Elizabeth

390

Evolution of the biosphere and fossil fuels  

SciTech Connect

The effect of fundamental events in biological evolution on the scale of fossil-fuel accumulation from the historical aspect is considered. Four main stages in the establishment of the ancient biospheres are recognized: pro-, proto-, neoto-, and acmeobiospheres. The hypothesis is based on especially favorable conditions for the formation of oil and fossil fuels during late Archean and early Proterozoic time. Their composition did not vary appreciably. During the Phanerozoic Eon, when the development of a mature biosphere reached its apogee, the explosion-like increase in complexity of the organic world changed the relationships of a number of fossil fuels and their evolutionary history in a radical way. This led to manifold differentiation within each type of fossil fuel.

Lopatin, N.V.

1980-10-01

391

Living-fossil coccolithophore survivors of the Cretaceous-Paleogene mass extinction  

NASA Astrophysics Data System (ADS)

Calcareous nannofossils (coccolithophores and other associated fossils), diversified greatly through the middle-late Mesozoic, but around 90% of these species became extinct at the K/Pg event. Although the specific cause of this mass extinction is still uncertain, the record of extinction and survivorship of nannoplankton has informed our understanding of the rates of extinction and recovery, and nature of survivorship in the plankton ecosystem. Recently we found living cells of a coccolithophore, which morphologically and structurally resembles the Mesozoic genus Cyclagelosphaera, from coastal-neritic waters of Tottori, Japan and of Rovinj, Croatia. Cyclagelosphaera is a characteristic Mesozoic genus that appeared in the middle Jurassic. It survived the K/Pg event, briefly flourished in post K/Pg oceans, with other K/Pg survivors, but disappeared from the fossil record in the Eocene. Bibliographic study has revealed that our specimens correspond to a living species Tergestiella adriatica, which was discovered from offshore Rovinji in 1934 but has never since been reported. Molecular phylogenetic studies of T. adriatica based on SSU rDNA sequences show that T. adriatica branched from the base of the clade of other living coccolithophores. This result suggests that T. adriatica diverged from the ancestor of other coccolithophores before the diversification of other taxa and supports the inference that T. adriatica is a direct descendent of Mesozoic Cyclagelosphaera rather than a homoeomorph. Floristic studies of living coccolithophores show that T. adriatica coexists with Braarudosphaera bigelowii, another K/Pg survivor, in the coastal area of Tottori, Japan. In both Mesozoic and Cenozoic oceans, calcareous nannoplankton are typically open-ocean dwellers, but a few taxa are confined to coastal waters. Curiously, all three extant coccolithophores with Mesozoic fossil records are coastal, meanwhile the other extant taxa with Cenozoic fossil records are oceanic. Our observation of T. adriatica and B. bigelowii from coastal environments provides evidence that coastal coccolithophores survived the K/Pg event selectively, and reinforces the hypothesis that calcareous plankton were almost completely eliminated from oceanic environments. The clearance of Mesozoic oceanic taxa likely allowed the temporary flourishing of coastal survivors in open ocean until the evolution of new specialist open ocean taxa. This selectivity may indicate that ocean acidification was a contributory factor in the K/Pg extinctions.

Hagino, K.; Young, J. R.; Bown, P. R.; Godrijan, J.; Kogame, K.; Kulhanek, D. K.; Horiguchi, T.

2012-12-01

392

Jurassic Deformation in and Around the Ordos Basin, North China  

Microsoft Academic Search

The Jurassic era was an important period for tectonic development of the East Asia continent in general, and can be divided into two different deformation stages around the Ordos basin in particular. It was under weak extension during the Early to Middle Jurassic, with the stretching direction in N-S to NNE-SSW, and the stretching deformation mainly occurred in zones surrounding

Yueqiao ZHANG; Changzhen LIAO; Wei SHI; Tian ZHANG; Fangang GUO

2007-01-01

393

Architectural studies of Jurassic-Cretaceous fluvial units, Colorado Plateau  

SciTech Connect

A sixfold hierarchy of architectural elements and bounding surfaces evolved from outcrop studies of three fluvial units: Westwater Canyon member (WCM), Morrison Formation, Upper Jurassic; Torrivio sandstone member (TSM), Gallup Sandstone, Upper Cretaceous, northwestern New Mexico; and Kayenta Formation (KF), Lower Jurassic, southwestern Colorado. This hierarchy is discussed.

Miall, A.D.; Bromley, M.H.; Cowan, E.J.; Turner-Peterson, C.E.

1989-03-01

394

Upper Jurassic tidal flat megatracksites of Germany—coastal dinosaur migration highways between European islands, and a review of the dinosaur footprints  

Microsoft Academic Search

Dinosaur tracks occur at three vertebrate tracksites in north-western Germany, in the acanthicum\\/mutabilis ammonoid biozone of the basal Upper Kimmeridgian (Upper Jurassic, KIM 3-4 cycle, 152.70-152.10 Ma). The trackbeds are mud-cracked,\\u000a siliciclastic, tidal sand flat biolaminates, overlain by paleosol beds. Channels contain rare fossils of sauropod, ornithopod\\u000a and pterosaur bones as well as shark and plant remains. Large sauropod tracks of

Cajus Diedrich

2011-01-01

395

Neuroanatomy of the Marine Jurassic Turtle Plesiochelys etalloni (Testudinata, Plesiochelyidae)  

PubMed Central

Turtles are one of the least explored clades regarding endocranial anatomy with few available descriptions of the brain and inner ear of extant representatives. In addition, the paleoneurology of extinct turtles is poorly known and based on only a few natural cranial endocasts. The main goal of this study is to provide for the first time a detailed description of the neuroanatomy of an extinct turtle, the Late Jurassic Plesiochelysetalloni, including internal carotid circulation, cranial endocast and inner ear, based on the first digital 3D reconstruction using micro CT scans. The general shape of the cranial endocast of P. etalloni is tubular, with poorly marked cephalic and pontine flexures. Anteriorly, the olfactory bulbs are clearly differentiated suggesting larger bulbs than in any other described extinct or extant turtle, and indicating a higher capacity of olfaction in this taxon. The morphology of the inner ear of P. etalloni is comparable to that of extant turtles and resembles those of slow-moving terrestrial vertebrates, with markedly low, short and robust semicircular canals, and a reduced lagena. In P. etalloni the arterial pattern is similar to that found in extant cryptodires, where all the internal carotid branches are protected by bone. As the knowledge of paleoneurology in turtles is scarce and the application of modern techniques such as 3D reconstructions based on CT scans is almost unexplored in this clade, we hope this paper will trigger similar investigations of this type in other turtle taxa. PMID:23844257

Carabajal, Ariana Paulina; Sterli, Juliana; Muller, Johannes; Hilger, Andre

2013-01-01

396

Ecological succession of a Jurassic shallow-water ichthyosaur fall  

PubMed Central

After the discovery of whale fall communities in modern oceans, it has been hypothesized that during the Mesozoic the carcasses of marine reptiles created similar habitats supporting long-lived and specialized animal communities. Here, we report a fully documented ichthyosaur fall community, from a Late Jurassic shelf setting, and reconstruct the ecological succession of its micro- and macrofauna. The early ‘mobile-scavenger’ and ‘enrichment-opportunist’ stages were not succeeded by a ‘sulphophilic stage’ characterized by chemosynthetic molluscs, but instead the bones were colonized by microbial mats that attracted echinoids and other mat-grazing invertebrates. Abundant cemented suspension feeders indicate a well-developed ‘reef stage’ with prolonged exposure and colonization of the bones prior to final burial, unlike in modern whale falls where organisms such as the ubiquitous bone-eating worm Osedax rapidly destroy the skeleton. Shallow-water ichthyosaur falls thus fulfilled similar ecological roles to shallow whale falls, and did not support specialized chemosynthetic communities. PMID:25205249

Danise, Silvia; Twitchett, Richard J.; Matts, Katie

2014-01-01

397

Ecological succession of a Jurassic shallow-water ichthyosaur fall.  

PubMed

After the discovery of whale fall communities in modern oceans, it has been hypothesized that during the Mesozoic the carcasses of marine reptiles created similar habitats supporting long-lived and specialized animal communities. Here, we report a fully documented ichthyosaur fall community, from a Late Jurassic shelf setting, and reconstruct the ecological succession of its micro- and macrofauna. The early 'mobile-scavenger' and 'enrichment-opportunist' stages were not succeeded by a 'sulphophilic stage' characterized by chemosynthetic molluscs, but instead the bones were colonized by microbial mats that attracted echinoids and other mat-grazing invertebrates. Abundant cemented suspension feeders indicate a well-developed 'reef stage' with prolonged exposure and colonization of the bones prior to final burial, unlike in modern whale falls where organisms such as the ubiquitous bone-eating worm Osedax rapidly destroy the skeleton. Shallow-water ichthyosaur falls thus fulfilled similar ecological roles to shallow whale falls, and did not support specialized chemosynthetic communities. PMID:25205249

Danise, Silvia; Twitchett, Richard J; Matts, Katie

2014-01-01

398

Fossil-energy program  

NASA Astrophysics Data System (ADS)

The increased utilization of coal and other fossil fuel alternatives as sources of clean energy is reported. The projects reported include: coal conversion development, chemical research and development, materials technology, component development and process evaluation, technical support to major liquefaction, process analysis and engineering evaluations, fossil energy environmental analysis, environmental control technology, coal preparation waste utilization, atmospheric fluidized bed coal combustor for cogeneration, TVA FBC demonstration plant program technical support, PFBC systems analysis, FBC char utilization improvement, fossil fuel applications assessments, performance assurance system support for fossil energy projects, international energy technology, generalized equilibrium models for liquid and gaseous fuel supplies, instrumentations and controls and fossil energy information center.

McNeese, L. E.

1982-01-01

399

Fossils of Kentucky  

NSDL National Science Digital Library

Information on Kentucky fossils is organized by type, age, and region. General fossil facts are given, and there are out-of-print technical reports available at this site. A fossil identification key helps users identify unknown fossils by shape or by descriptive terms. A Geologic and Paleontologic Cookbook offers directions for creating edible models that illustrate prehistoric and other Earth Science concepts (such as trilobite cookies and layer-cake geology). There are links to more K-12 activities and other fossil websites.

400

A fossil flora from the Frontier formation of southwestern Wyoming  

USGS Publications Warehouse

This paper deals with a small but important fossil flora, now known to be of Colorado age, from the vicinity of Cumberland, Lincoln County, Wyo. It was for many years thought to be of Jurassic age, and only within the last decade has its stratigraphic position been established. Although small in number of species, this flora offers information bearing on the physical and climatic conditions that prevailed during early Upper Cretaceous time in this region, and, moreover, it furnishes a series of stratigraphic marks that may be used in the recognition of this horizon elsewhere.

Knowlton, F.H.

1917-01-01

401

Adaptation, plant evolution, and the fossil record  

NASA Technical Reports Server (NTRS)

The importance of adaptation in determining patterns of evolution has become an important focus of debate in evolutionary biology. As it pertains to paleobotany, the issue is whether or not adaptive evolution mediated by natural selection is sufficient to explain the stratigraphic distributions of taxa and character states observed in the plant fossil record. One means of addressing this question is the functional evaluation of stratigraphic series of plant organs set in the context of paleoenvironmental change and temporal patterns of floral composition within environments. For certain organ systems, quantitative estimates of biophysical performance can be made on the basis of structures preserved in the fossil record. Performance estimates for plants separated in time or space can be compared directly. Implicit in different hypotheses of the forces that shape the evolutionary record (e.g. adaptation, mass extinction, rapid environmental change, chance) are predictions about stratigraphic and paleoenvironmental trends in the efficacy of functional performance. Existing data suggest that following the evolution of a significant structural innovation, adaptation for improved functional performance can be a major determinant of evolutionary changes in plants; however, there are structural and development limits to functional improvement, and once these are reached, the structure in question may no longer figure strongly in selection until and unless a new innovation evolves. The Silurian-Devonian paleobotanical record is consistent with the hypothesis that the succession of lowland floodplain dominants preserved in the fossil record of this interval was determined principally by the repeated evolution of new taxa that rose to ecological importance because of competitive advantages conferred by improved biophysical performance. This does not seem to be equally true for Carboniferous-Jurassic dominants of swamp and lowland floodplain environments. In these cases, environmental disruption appears to have been a major factor in shaping the fossil record. This does not mean that continuing adaptation was not important during this interval, but it may indicate that adaptive evolution was strongest in environments other than those best represented in the paleobotanical record.

Knoll, A. H.; Niklas, K. J.

1987-01-01

402

Jurassic plume-origin ophiolites in Japan: accreted fragments of oceanic plateaus  

NASA Astrophysics Data System (ADS)

The Mikabu and Sorachi-Yezo belts comprise Jurassic ophiolitic complexes in Japan, where abundant basaltic to picritic rocks occur as lavas and hyaloclastite blocks. In the studied northern Hamamatsu and Dodaira areas of the Mikabu belt, these rocks are divided into two geochemical types, namely depleted (D-) and enriched (E-) types. In addition, highly enriched (HE-) type has been reported from other areas in literature. The D-type picrites contain highly magnesian relic olivine phenocrysts up to Fo93.5, and their Fo-NiO trend indicates fractional crystallization from a high-MgO primary magma. The MgO content is calculated as high as 25 wt%, indicating mantle melting at unusually high potential temperature ( T p) up to 1,650 °C. The E-type rocks represent the enrichment in Fe and LREE and the depletion in Mg, Al and HREE relative to the D-type rocks. These chemical characteristics are in good accordance with those of melts from garnet pyroxenite melting. Volcanics in the Sorachi-Yezo belts can be divided into the same types as the Mikabu belt, and the D-type picrites with magnesian olivines also show lines of evidence for production from high T p mantle. Evidence for the high T p mantle and geochemical similarities with high-Mg picrites and komatiites from oceanic and continental large igneous provinces (LIPs) indicate that the Mikabu and Sorachi-Yezo belts are accreted oceanic LIPs that were formed from hot large mantle plumes in the Late Jurassic Pacific Ocean. The E- and D-type rocks were formed as magmas generated by garnet pyroxenite melting at an early stage of LIP magmatism and by depleted peridotite melting at the later stage, respectively. The Mikabu belt characteristically bears abundant ultramafic cumulates, which could have been formed by crystal accumulation from a primary magma generated from Fe-rich peridotite mantle source, and the HE-type magma were produced by low degrees partial melting of garnet pyroxenite source. They should have been formed later and in lower temperatures than the E- and D-type rocks. The Mikabu and Sorachi Plateaus were formed in a low-latitude region of the Late Jurassic Pacific Ocean possibly near a subduction zone, partially experienced high P/ T metamorphism during subduction, and then uplifted in association with (or without, in case of Mikabu) the supra-subduction zone ophiolite. The Mikabu and Sorachi Plateaus may be the Late Jurassic oceanic LIPs that could have been formed in brotherhood with the Shatsky Rise.

Ichiyama, Yuji; Ishiwatari, Akira; Kimura, Jun-Ichi; Senda, Ryoko; Miyamoto, Tsuyoshi

2014-07-01

403

Late pleistocene passerine birds from Sonora, Mexico  

Microsoft Academic Search

Songbirds (Passeriformes) have a very limited fossil record in spite of making up more than one-half of the world's 10,000 living species of birds. From the late Pleistocene fossil site of Térapa in east-central Sonora, Mexico, the identifiable fossils of songbirds consist exclusively of species of Icteridae. The seven extant species (Red-winged Blackbird Agelaius phoeniceus, Yellow-headed Blackbird Xanthocephalus xanthocephalus, Brewer's

Jessica A. Oswald; David W. Steadman

2011-01-01

404

Fossil Mapping of Utah  

NSDL National Science Digital Library

Fossils are evidence of living organisms from the past and are usually preserved in sedimentary rocks. A fossil may be an impression left in sediments, the preserved remains of an organism, or a trace mark showing that an organism once existed. Fossils are usually made from the hard parts of an organism because soft parts decay quickly. Fossils provide clues to Earth's history. They provide evidence that can be used to make inferences about past environments. Fossils can be compared to one another, to living organisms, and to organisms that lived long ago. Students will understand how fossils are formed, where they may be found in Utah, and how they can be used to make inferences. Research locations where fossils are found in Utah and construct a simple fossil map. 4th Grade Utah Core Curriculum, Science Benchmark, Standard 4, Objective 1, UEN TASK Congratulations. You have all become Paleontologists. You study fossils and it is your job to map the fossils of Utah for the State. Students will be divided into 4 groups. Each group will be given a Utah County Map. Each group will focus on one category ...

Ramsey

2009-11-18

405

Gondwana to Asia: Plate tectonics, paleogeography and the biological connectivity of the Indian sub-continent from the Middle Jurassic through latest Eocene (166 35 Ma)  

NASA Astrophysics Data System (ADS)

Using the most up-to-the-date information available, we present a considerably revised plate tectonic and paleogeographic model for the Indian Ocean bordering continents, from Gondwana's Middle Jurassic break-up through to India's collision with Asia in the middle Cenozoic. The landmass framework is then used to explore the sometimes complex and occasionally counter-intuitive patterns that have been observed in the fossil and extant biological records of India, Madagascar, Africa and eastern Eurasia, as well those of the more distal continents. Although the paleogeographic model confirms the traditional view that India became progressively more isolated from the major landmasses during the Cretaceous and Paleocene, it is likely that at various times minor physiographic features (principally ocean islands) provided causeways and/or stepping-stone trails along which land animals could have migrated to/from the sub-continent. Aside from a likely link (albeit broken by several marine gaps) to Africa for much of this time (it is notable, that the present-day/recent biota of Madagascar indicates that the ancestors of five land-mammal orders, plus bats, crossed the > 400-km-wide Mozambique Channel at different times in the Cenozoic), it is possible that the Kerguelen Plateau connected India and Australia-Antarctica in the mid-Cretaceous (approximately 115-90 Ma). Later, the Seychelles-Mascarene Plateau and nearby elevated sea-floor areas could have allowed faunas to pass between southern India and Madagascar in the Late Cretaceous, from around 85-65 Ma, with an early Cenozoic extension to this path forming as a result of the Reunion hot-spot trace islands growing on the ocean floor to the SSW of India. The modelling also suggests that India's northward passage towards Asia, with eventual collision at 35 Ma, involved the NE corner of the sub-continent making a glancing contact with Sumatra, followed by Burma from ~ 57 Ma (late Paleocene) onwards, a scenario which is compatible with the fossil record indicating that India-Asia faunal exchanges began occurring at about this time. Finally, we contend that a number of biologically-based direct terrestrial migration routes that have been proposed for last 15 m.y. of the Cretaceous (Asia to India; Antarctica to Madagascar and/or India) can probably be dismissed because the marine barriers, likely varying from > 1000 up to 2500 km, were simply too wide.

Ali, Jason R.; Aitchison, Jonathan C.

2008-06-01

406

Post-Jurassic tectonic evolution of Southeast Asia  

NASA Astrophysics Data System (ADS)

The accretionary growth of Asia, linked to long-term convergence between Eurasia, Gondwana-derived blocks and the Pacific, resulted in a mosaic of terranes for which conflicting tectonic interpretations exist. Here, we propose solutions to a number of controversies related to the evolution of Sundaland through a synthesis of published geological data and plate reconstructions that reconcile both geological and geophysical constraints with plate driving forces. We propose that West Sulawesi, East Java and easternmost Borneo rifted from northern Gondwana in the latest Jurassic, collided with an intra-oceanic arc at ~115 Ma and subsequently sutured to Sundaland by 80 Ma. Although recent models argue that the Southwest Borneo core accreted to Sundaland at this time, we use volcanic and biogeographic constraints to show that the core of Borneo was on the Asian margin since at least the mid Jurassic. This northward transfer of Gondwana-derived continental fragments required a convergent plate boundary in the easternmost Tethys that we propose gave rise to the Philippine Archipelago based on the formation of latest Jurassic-Early Cretaceous supra-subduction zone ophiolites on Halmahera, Obi Island and Luzon. The Late Cretaceous marks the shift from Andean-style subduction to back-arc opening on the east Asian margin. Arc volcanism along South China ceased by ~60 Ma due to the rollback of the Izanagi slab, leading to the oceanward migration of the volcanic arc and the opening of the Proto South China Sea (PSCS). We use the Apennines-Tyrrhenian system in the Mediterranean as an analogue to model this back-arc. Continued rollback detaches South Palawan, Mindoro and the Semitau continental blocks from the stable east Asian margin and transfers them onto Sundaland in the Eocene to produce the Sarawak Orogeny. The extrusion of Indochina and subduction polarity reversal along northern Borneo opens the South China Sea and transfers the Dangerous Grounds-Reed Bank southward to terminate PSCS south-dipping subduction and culminates in the Sarawak Orogeny on Borneo and ophiolite obduction on Palawan. We account for the regional plate reorganizations related to the initiation of Pacific subduction along the Izu-Bonin-Mariana Arc, the extrusion tectonics resulting from the India-Eurasia collision, and the shift from basin extension to inversion on Sundaland as an indicator of collision between the Australian continent and the active Asian margin. We generate continuously closing and evolving plate boundaries, seafloor age-grids and global plate velocity fields using the open-source and cross-platform GPlates plate reconstruction software. We link our plate motions to numerical mantle flow models in order to predict mantle structure at present-day that can be qualitatively compared to P- and S- wave seismic tomography models. This method allows us to analyse the evolution of the mantle related to Tethyan and Pacific subduction and to test alternative plate reconstructions. This iterative approach can be used to improve plate reconstructions in the absence of preserved seafloor and conjugate passive margins of continental blocks, which may have been destroyed or highly deformed by multiple episodes of accretion along the Asian margins.

Zahirovic, Sabin; Seton, Maria; Dietmar Müller, R.; Flament, Nicolas

2014-05-01

407

The first Lower Jurassic dinosaur from Scotland: limb bone of a ceratosaur theropod from Skye  

E-print Network

The first Lower Jurassic dinosaur from Scotland: limb bone of a ceratosaur theropod from Skye M. J right tibia of a carnivorous dinosaur is reported from the Lower Jurassic Broadford Beds Formation widespread during the Early Jurassic. This tibia, and a partial sauropod tibia from the Middle Jurassic

Benton, Michael

408

Following votes by the Pliensbachian Working Group, the Jurassic Subcommission and the International Commis-  

E-print Network

Following votes by the Pliensbachian Working Group, the Jurassic Subcommission and Point (GSSP) for the base of the Pliensbachian Stage (Lower Jurassic) at the base of bed 73b in the Wine. Foreword The Pliensbachian is the third Stage of the Jurassic System, and the fourth Jurassic Stage

409

A Jurassic avialan dinosaur from China resolves the early phylogenetic history of birds.  

PubMed

The recent discovery of small paravian theropod dinosaurs with well-preserved feathers in the Middle-Late Jurassic Tiaojishan Formation of Liaoning Province (northeastern China) has challenged the pivotal position of Archaeopteryx, regarded from its discovery to be the most basal bird. Removing Archaeopteryx from the base of Avialae to nest within Deinonychosauria implies that typical bird flight, powered by the forelimbs only, either evolved at least twice, or was subsequently lost or modified in some deinonychosaurians. Here we describe the complete skeleton of a new paravian from the Tiaojishan Formation of Liaoning Province, China. Including this new taxon in a comprehensive phylogenetic analysis for basal Paraves does the following: (1) it recovers it as the basal-most avialan; (2) it confirms the avialan status of Archaeopteryx; (3) it places Troodontidae as the sister-group to Avialae; (4) it supports a single origin of powered flight within Paraves; and (5) it implies that the early diversification of Paraves and Avialae took place in the Middle-Late Jurassic period. PMID:23719374

Godefroit, Pascal; Cau, Andrea; Dong-Yu, Hu; Escuillié, François; Wenhao, Wu; Dyke, Gareth

2013-06-20

410

Evolution of Cambrian to Ordovician trace fossils in pelagic deep-sea chert, Australia  

Microsoft Academic Search

Cambrian to Ordovician pelagic radiolarian cherts in the Lachlan Fold Belt in southeastern Australia contain trace fossils demonstrating the faunal diversification that occurred during the Ordovician on the deep-sea floor. The Cambro-Ordovician Howqua Chert has a very low degree of bioturbation, and the trace fossils are small and shallow. In contrast, the late Middle to Late Ordovician cherts are strongly

Y. Kakuwa; J. Webb

2010-01-01

411

A giant spider from the Jurassic of China reveals greater diversity of the orbicularian stem group  

NASA Astrophysics Data System (ADS)

A large female spider, Nephila jurassica, was described from Middle Jurassic strata of north-east China and placed in the modern genus Nephila (family Nephilidae) on the basis of many morphological similarities, but, as with many ancient fossils, the single specimen lacked synapomorphies of the family (Selden et al. 2011). In order to test the placement within the nephilid phylogenetic tree, Kuntner et al. (2013) calibrated the molecular phylogeny using N. jurassica in three different scenarios based on inferred mitochondrial substitution rates. They concluded that N. jurassica fitted better as a stem orbicularian than a nephilid. Now, a giant male spider has been discovered at the same locality that yielded N. jurassica. The two sexes are considered conspecific based on their similar morphological features, size, and provenance. The male cannot be accommodated in Nephilidae because of its pedipalp morphology, so the new genus Mongolarachne and family Mongolarachnidae are erected for the species. Comparison with possibly related families show that Mongolarachnidae is most likely on the orbicularian stem, close to other cribellate orbicularians (e.g., Deinopoidea), which suggests a greater diversity of cribellate orbicularians during the Middle Jurassic.

Selden, Paul A.; Shih, ChungKun; Ren, Dong

2013-12-01

412

Jurassic-Early Cretaceous Gondwanan homoxylous woods: a nomenclatural revision of the genera with taxonomic notes.  

PubMed

The homoxylous fossil woods occurring in the Gondwanan continents of South America, Australia, Africa, India and Antarctica during the Jurassic and Early Cretaceous period are considered here. Original descriptions of the genera and wherever possible, the type material, have been consulted. Applying the rules of the International Code of Botanical Nomenclature, the generic names of the homoxylous woods have been revised from a nomenclatural point of view. According to this review, out of 31 generic names used for woods from the given time interval and area, 6 are illegitimate later nomenclatural synonyms, 1 is a later homonym, and 5 can be considered as taxonomical synonyms. Moreover, 9 genera have been used erroneously. We propose one new generic name (Protaxodioxylon n. gen.) and elsewhere we will propose for conservation, with a conserved type one of the illegitimate names and one of the taxonomic synonyms. As a result, we consider that there are only eighteen generic names correctly quoted for the Jurassic-Early Cretaceous of Gondwana, and we provide a taxonomic key for the corresponding genera. This revision is the first step in systematically comparing northern and southern hemisphere woods. PMID:11179718

Bamford, M K.; Philippe, M

2001-04-01

413

A giant spider from the Jurassic of China reveals greater diversity of the orbicularian stem group.  

PubMed

A large female spider, Nephila jurassica, was described from Middle Jurassic strata of north-east China and placed in the modern genus Nephila (family Nephilidae) on the basis of many morphological similarities, but, as with many ancient fossils, the single specimen lacked synapomorphies of the family (Selden et al. 2011). In order to test the placement within the nephilid phylogenetic tree, Kuntner et al. (2013) calibrated the molecular phylogeny using N. jurassica in three different scenarios based on inferred mitochondrial substitution rates. They concluded that N. jurassica fitted better as a stem orbicularian than a nephilid. Now, a giant male spider has been discovered at the same locality that yielded N. jurassica. The two sexes are considered conspecific based on their similar morphological features, size, and provenance. The male cannot be accommodated in Nephilidae because of its pedipalp morphology, so the new genus Mongolarachne and family Mongolarachnidae are erected for the species. Comparison with possibly related families show that Mongolarachnidae is most likely on the orbicularian stem, close to other cribellate orbicularians (e.g., Deinopoidea), which suggests a greater diversity of cribellate orbicularians during the Middle Jurassic. PMID:24317464

Selden, Paul A; Shih, Chungkun; Ren, Dong

2013-12-01

414

Bird-like anatomy, posture, and behavior revealed by an early jurassic theropod dinosaur resting trace  

USGS Publications Warehouse

Background: Fossil tracks made by non-avian theropod dinosaurs commonly reflect the habitual bipedal stance retained in living birds. Only rarely-captured behaviors, such as crouching, might create impressions made by the hands. Such tracks provide valuable information concerning the often poorly understood functional morphology of the early theropod forelimb. Methodology/Principal Findings: Here we describe a well-preserved theropod trackway in a Lower Jurassic (???198 millionyear- old) lacustrine beach sandstone in the Whitmore Point Member of the Moenave Formation in southwestern Utah. The trackway consists of prints of typical morphology, intermittent tail drags and, unusually, traces made by the animal resting on the substrate in a posture very similar to modern birds. The resting trace includes symmetrical pes impressions and well-defined impressions made by both hands, the tail, and the ischial callosity. Conclusions/Significance: The manus impressions corroborate that early theropods, like later birds, held their palms facing medially, in contrast to manus prints previously attributed to theropods that have forward-pointing digits. Both the symmetrical resting posture and the medially-facing palms therefore evolved by the Early Jurassic, much earlier in the theropod lineage than previously recognized, and may characterize all theropods.

Milner, A. R. C.; Harris, J. D.; Lockley, M. G.; Kirkland, J. I.; Matthews, N. A.

2009-01-01

415

Tiny Fossil Sheds Light on Mammalian Evolution  

NSDL National Science Digital Library

In the most recent issue of Science, a team of American and Chinese scientists announced the discovery of the fossil of a tiny shrew-like creature that lived 195 million years ago, 45 million years before previously discovered mammals. Found in 1985 in Yunnan province, China, the fossil was originally believed to be merely a bone fragment because of its small size. It has now been named Hadrocodium wui, ("Fullhead"), and could possibly be the direct ancestor of all living mammals. Hadrocodium was an insectivore, eating worms and small insects. Though it weighed only two grams (the weight of a paper clip), Hadrocodium had a considerably larger brain than most known mammals from the early Jurassic period. The tiny skull also possesses three other key traits that are characteristic of the transition from mammal-like animals to true mammals: a three-bone middle ear separated from the jaw, matching upper and lower teeth, and a powerful jaw hinge. Readers can begin learning more about this discovery with the Science article. Additional coverage is provided by Discovery news, the BBC, National Geographic, ABC News, and CNN.

De Nie, Michael W.

2001-01-01

416

Does the Great Valley Group contain Jurassic strata? Reevaluation of the age and early evolution of a classic forearc basin  

USGS Publications Warehouse

The presence of Cretaceous detrital zircon in Upper Jurassic strata of the Great Valley Group may require revision of the lower Great Valley Group chronostratigraphy, with significant implications for the Late Jurassic-Cretaceous evolution of the continental margin. Samples (n = 7) collected from 100 km along strike in the purported Tithonian strata of the Great Valley Group contain 20 Cretaceous detrital zircon grains, based on sensitive high-resolution ion microprobe age determinations. These results suggest that Great Valley Group deposition was largely Cretaceous, creating a discrepancy between biostratigraphy based on Buchia zones and chronostratigraphy based on radiometric age dates. These results extend the duration of the Great Valley Group basal unconformity, providing temporal separation between Great Valley forearc deposition and creation of the Coast Range Ophiolite. If Great Valley forearc deposition began in Cretaceous time, then sediment by passed the developing forearc in the Late Jurassic, or the Franciscan subduction system did not fully develop until Cretaceous time. In addition to these constraints on the timing of deposition, pre-Mesozoic detrital zircon age signatures indicate that the Great Valley Group was linked to North America from its inception. ?? 2006 Geological Society of America.

Surpless, K. D.; Graham, S. A.; Covault, J. A.; Wooden, J. L.

2006-01-01

417

Fossil Energy Website  

NSDL National Science Digital Library

This site serves as a gathering point for US Department of Energy (USDOE) materials related to fossil energy. Well-organized and easily navigated, the Fossil Energy Website hosts a wealth of resources, including fossil energy news, related USDOE budget information, an events calendar, in-depth explorations of selected issues, speeches and testimony, technical reports, statistics, and an overview of fossil energy-related global activities, among others. Additional resources include regulatory information, a news headlines ticker, a free email update service, related links, and professional notices.

418

Plant Fossil Record  

NSDL National Science Digital Library

The International Organization of Palaeobotany (IOP) manages the Plant Fossil Record (PFR) database. The recently released version of the database, PFR2.2, offers descriptive details of most plant fossil genera and modern genera with fossil species. Based on "the scientific literature ... or museum collections," the database is organized into five sections: Genera (references for plant fossil genera published mostly before 1985), Descriptions (containing descriptive details of "the type specimens of more than 10,000 extinct plant genera"), Taxonomy (an "informal system of vascular plant classification" based on published schemes), Occurrences (distribution information and references), and Palaeo Maps.

419

Geology, fossil fuel potential and environmental concerns of the Caspian Sea  

Microsoft Academic Search

The fossil fuel producing areas of the Caspian region consists primarily of two basins, the Precaspian and South Caspian basins, both containing sediments in excess of 20km. The South Caspian Basin, a remnant of Tethys, was formed commencing in the Early-Middle Jurassic as a result of opening of back-arc basins behind volcanic arcs. The PreCaspian Basin extends onshore onto Kazakhstan

P. Rabinowitz; M. Yusifov; J. Arnoldi

2003-01-01

420

Middle Jurassic stratigraphy in the southwestern part of the Republic of Tatarstan  

NASA Astrophysics Data System (ADS)

Data on the structure of the Middle Jurassic marine deposits in the vicinity of Ulyanovsk (sections of the Tarkhanovskaya Pristan-Dolinovka profile) are generalized with due regard for ammonites, bivalves, and microfossils occurring in sediments. Outcrops of the Tarkhanovskaya Pristan site represent the northernmost Bajocian section of the Russian Platform, where ammonites of Tethyan origin are identified. As is established, the pre-Callovian sand-clay sequence formerly attributed to the Bathonian includes the Garantiana beds of the upper Bajocian in its middle part. The multidisciplinary biostratigraphic-sedimentological research showed that downwarping of the Ulyanovsk-Saratov basin and origin of the Simbirsk Bay of the Tethyan marginal sea commenced in the Bajocian Age. The identified fossils of the upper Bajocian and lower and upper Callovian are cited in paleontological plates of this work.

Mitta, V. V.; Kostyleva, V. V.; Glinskikh, L. A.; Shurygin, B. N.; Starodubtseva, I. A.

2014-01-01

421

Ichnofabric mapping and interpretation of Jurassic reservoir rocks of the Norwegian North Sea  

SciTech Connect

Recurrent sediment fabric and trace fossil associations in the Norwegian offshore Jurassic sequences have been interpreted by the ichnofabric concept. In the Sognefjord Formation (Oxfordian-Kimmeridgian) of the Troll Field five basic ichnofabrics were recognized and named after the dominant ichnogenus present, respectively: Helminthoida, Anconichnus, Palaeophycus, Ophiomorpha and Skolithos. These ichnofabrics developed in sediments deposited in marine environments ranging from quiescent offshore to high energy, shallow water nearshore situations. When sequence patterns of ichnofabrics were mapped within five chronostratigraphic reservoir zones of the Troll Field it was possible to recognize both how the frequency of a given ichnofabric may change in time in a restricted area or may change in its areal distribution in a restricted time interval. Such maps have been integrated with lithofacies maps and dip-meter studies in cored sequence to produce quantitative base maps for computerized reservoir models. The maps can also be used as a powerful tool for facies predictions.

Bockelie, J.F. (Norsk Hydro Exploration, Stabekk (Norway))

1991-06-01

422

Grazing trails formed by soldier fly larvae (Diptera: Stratiomyidae) and their paleoenvironmental and paleoecological implications for the fossil record  

USGS Publications Warehouse

Recent trails formed by soldier fly larvae (Diptera: Stratiomyidae) were examined in a shallow pond in the floodplain of a braided river in Jujuy Province, northwestern Argentina. Collected specimens were identified as Stratiomys convexa van der Wulp. Simple, irregularly meandering trails were produced across the surface of a muddy-silty substrate. Since soldier fly larvae extend their caudal respiratory tube to the water-air interface, they are restricted to extremely shallow water. The presence of benthic algal remains within the mouthparts of the larvae suggests a feeding habit of algal grazing. If preserved, these trails would be included in the ichnogenus Helminthopsis, a common element in ancient freshwater ichnofaunas. Helminthopsis preserved in pond and lacustrine margin deposits younger than Late Jurassic is regarded as one possible trace fossil analogue of the trails documented herein. Additionally, it is suggested that larvae of many aquatic Diptera with similar ecologic restrictions are potential tracemakers of Helminthopsis and other simple trails in these environments, particularly in post-Paleozoic deposits. Studies of modern shallow aquatic habitats and reexamination of the ichnologic record stress the importance of fly larvae as tracemakers in lake margin and pond ecosystems. Ecologic requirements of soldier fly larvae make them inappropriate analogues of Helminthopsis tracemakers in deeper water, lacustrine settings. ?? 1996 OPA (Overseas Publishers Association) Amsterdam B.V. Published in The Netherlands by Harwood Academic Publishers GmbH.

Mangano, M. G.; Buatois, L. A.; Claps, G. L.

1996-01-01

423

Late Mesozoic–Cenozoic sedimentary basins of active continental margin of Southeast Russia: paleogeography, tectonics, and coal–oil–gas presence  

Microsoft Academic Search

Various settings took place during the Late Mesozoic: divergent, convergent, collisional, and transform. After mid-Jurassic collision of the Siberian and Chinese cratons, a latitudinal system of post-collision troughs developed along the Mongol-Okhotsk suture (the Uda, Torom basins and others), filled with terrigenous coal-bearing molasse.The dispersion of Pangea, creation of oceans during the Late Jurassic are correlated to the emergence of

Galina L Kirillova

2003-01-01

424

Evidence of Evolution I. Fossils and the fossil record  

E-print Network

1 Evidence of Evolution I. Fossils and the fossil record · "First and foremost among the databases deposited in those Eras. #12;2 Why is the fossil record incomplete? · fossilization - "lucky accidents · conditions needed for fossilization ­ Rapid burial ­ Hard parts ­ Process unlikely in tropical regions http://www.pbs.org/wgbh/evolution

Dever, Jennifer A.

425

Evidence of Evolution I. Fossils and the fossil record  

E-print Network

Evidence of Evolution #12;I. Fossils and the fossil record � "First and foremost among in the rocks deposited in those Eras. #12;#12;Why is the fossil record incomplete? � fossilization - "lucky the step-by-step transition to becoming a tetrapod Origin of higher taxa recorded in the fossil record: 1

Dever, Jennifer A.

426

The change from rifting to thrusting in the Northern Calcareous Alps as recorded in Jurassic sediments  

Microsoft Academic Search

Facies analysis, fossil dating, and the study of the metamorphism in the Late Triassic to Early Cretaceous sedimentary successions in the central part of the Northern Calcareous Alps allow to reconstruct the tectonic evolution in the area between the South Penninic Ocean in the northwest and the Tethys Ocean with the Hallstatt Zone in the southeast. The Triassic as well

H.-J. Gawlick; A. Vecsei; T. Steiger; W. Frisch

1999-01-01

427

Fossilized nuclei and chromosomes reveal 180 million years of genomic stasis in royal ferns.  

PubMed

Rapidly permineralized fossils can provide exceptional insights into the evolution of life over geological time. Here, we present an exquisitely preserved, calcified stem of a royal fern (Osmundaceae) from Early Jurassic lahar deposits of Sweden in which authigenic mineral precipitation from hydrothermal brines occurred so rapidly that it preserved cytoplasm, cytosol granules, nuclei, and even chromosomes in various stages of cell division. Morphometric parameters of interphase nuclei match those of extant Osmundaceae, indicating that the genome size of these reputed "living fossils" has remained unchanged over at least 180 million years-a paramount example of evolutionary stasis. PMID:24653037

Bomfleur, Benjamin; McLoughlin, Stephen; Vajda, Vivi

2014-03-21

428

Restoring Fossil Creek  

ERIC Educational Resources Information Center

Fossil Creek had been dammed for the past 90 years, and plans were underway to restore the stream. The creek runs through Central Arizona and flows from the high plateaus to the desert, cutting through the same formations that form the Grand Canyon. This article discusses the Fossil Creek monitoring project. In this project, students and teachers…

Flaccus, Kathleen; Vlieg, Julie; Marks, Jane C.; LeRoy, Carri J.

2004-01-01

429

"It's Alive!" Fossil Activity  

NSDL National Science Digital Library

The first lab activity for the course is called "PaleontologyâPast, Present, and Future". In addition to discussing several documents related to present and future research directions in the field, students review a brief timeline of the historical development of paleontology as a science. Then they get their first opportunity to work directly with fossils. Students are presented with a set of fossil specimens in boxes (with no identifying labels). Each student selects one fossil of their own. They are asked to make and record very close, detailed observations of the specimen, and to sketch the fossil. Then they are told to "think like it's 1600." Someone has brought this object, taken out of the local rocks, for the student to investigate. The student must write a "proof" that this fossil was obviously once alive, and is not just an interesting mineral or rock formation. They can use their observations, compare the specimen to other objects with which they're familiar, resort to pure logic, or apply any other avenue of argumentation they think will help make their case. Note: In the next lab, on fossil preservation and taphonomy, the students revisit their fossil specimen, and determine its mode of preservation. Indeed, the student's "pet fossil" could be used throughout the course to illustrate various components of the course content.

Yacobucci, Peg

430

Becoming a Fossil  

NSDL National Science Digital Library

This text and accompanying video provide an overview of how fossils are formed and preserved. A video clip from the NOVA television program, 'In Search of Human Origins', shows how the famous early hominid 'Lucy' might have died and been fossiliized, and points out the rare set of circumstances that must occur for an organism to be fossilized. Questions for discussion are included.

2005-01-01

431

Sustainable Fossil Fuels  

Microsoft Academic Search

More and more people believe we must quickly wean ourselves from fossil fuels - oil, natural gas and coal - to save the planet from environmental catastrophe, wars and economic collapse. Professor Jaccard argues that this view is misguided. We have the technological capability to use fossil fuels without emitting climate-threatening greenhouse gases or other pollutants. The transition from conventional

Mark Jaccard