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1

Getting to Know Homo erectus  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required. Europe and Asia have yielded a number of hominid fossils from the period 1 to 0.5 million years ago, but few hominid fossils from this era have been found in Africa. In his Perspective, Schwartz discusses a new hominid fossil find at Olorgesailie in Kenya, and whether it belongs to the species Homo erectus.

Jeffrey H. Schwartz (University of Pittsburgh;)

2004-07-02

2

Grandmothering and the evolution of homo erectus.  

PubMed

Despite recent, compelling challenge, the evolution of Homo erectus is still commonly attributed to big game hunting and/or scavenging and family provisioning by men. Here we use a version of the "grandmother" hypothesis to develop an alternative scenario, that climate-driven adjustments in female foraging and food sharing practices, possibly involving tubers, favored significant changes in ancestral life history, morphology, and ecology leading to the appearance, spread and persistence of H. erectus. Available paleoclimatic, environmental, fossil and archaeological data are consistent with this proposition; avenues for further critical research are readily identified. This argument has important implications for widely-held ideas about the recent evolution of long human lifespans, the prevalence of male philopatry among ancestral hominids, and the catalytic role of big game hunting and scavenging in early human evolution. PMID:10222165

O'connell, J F; Hawkes, K; Blurton Jones, N G

1999-05-01

3

Latest Homo erectus of Java: Potential Contemporaneity with Homo sapiens in Southeast Asia  

Microsoft Academic Search

Hominid fossils from Ngandong and Sambungmacan, Central Java, are considered the most morphologically advanced representatives of Homo erectus. Electron spin resonance (ESR) and mass spectrometric U-series dating of fossil bovid teeth collected from the hominid-bearing levels at these sites gave mean ages of 27 ± 2 to 53.3 ± 4 thousand years ago; the range in ages reflects uncertainties in

C. C. Swisher III; W. J. Rink; S. C. Anton; H. P. Schwarcz; G. H. Curtis; A. Suprijo; Widiasmoro

1996-01-01

4

African Homo erectus: Old Radiometric Ages and Young Oldowan Assemblages in the Middle Awash Valley, Ethiopia  

Microsoft Academic Search

Fossils and artifacts recovered from the middle Awash Valley of Ethiopia's Afar depression sample the Middle Pleistocene transition from Homo erectus to Homo sapiens. Ar\\/Ar ages, biostratigraphy, and tephrachronology from this area indicate that the Pleistocene Bodo hominid cranium and newer specimens are approximately 0.6 million years old. Only Oldowan chopper and flake assemblages are present in the lower stratigraphic

J. D. Clark; J. de Heinzelin; K. D. Schick; W. K. Hart; T. D. White; G. Woldegabriel; R. C. Walter; G. Suwa; B. Asfaw; E. Vrba; Y. H.-Selassie

1994-01-01

5

Remains of Homo erectus from Bouri, Middle Awash, Ethiopia  

Microsoft Academic Search

The genesis, evolution and fate of Homo erectus have been explored palaeontologically since the taxon's recognition in the late nineteenth century. Current debate is focused on whether early representatives from Kenya and Georgia should be classified as a separate ancestral species (`H. ergaster'), and whether H. erectus was an exclusively Asian species lineage that went extinct. Lack of resolution of

Berhane Asfaw; W. Henry Gilbert; Yonas Beyene; William K. Hart; Paul R. Renne; Giday WoldeGabriel; Elisabeth S. Vrba; Tim D. White

2002-01-01

6

New 1.5 million-year-old Homo erectus maxilla from Sangiran (Central Java, Indonesia).  

PubMed

Sangiran (Solo Basin, Central Java, Indonesia) is the singular Homo erectus fossil locale for Early Pleistocene Southeast Asia. Sangiran is the source for more than 80 specimens in deposits with (40)Ar/(39)Ar ages of 1.51-0.9 Ma. In April 2001, we recovered a H. erectus left maxilla fragment (preserving P(3)- M(2)) from the Sangiran site of Bapang. The find spot lies at the base of the Bapang Formation type section in cemented gravelly sands traditionally called the Grenzbank Zone. Two meters above the find spot, pumice hornblende has produced an (40)Ar/(39)Ar age of 1.51 ± 0.08 Ma. With the addition of Bpg 2001.04, Sangiran now has five H. erectus maxillae. We compare the new maxilla with homologs representing Sangiran H. erectus, Zhoukoudian H. erectus, Western H. erectus (pooled African and Georgian specimens), and Homo habilis. Greatest contrast is with the Zhoukoudian maxillae, which appear to exhibit a derived pattern of premolar-molar relationships compared to Western and Sangiran H. erectus. The dental patterns suggest distinct demic origins for the earlier H. erectus populations represented at Sangiran and the later population represented at Zhoukoudian. These two east Asian populations, separated by 5000 km and nearly 800 k.yr., may have had separate origins from different African/west Eurasian populations. PMID:21783226

Zaim, Yahdi; Ciochon, Russell L; Polanski, Joshua M; Grine, Frederick E; Bettis, E Arthur; Rizal, Yan; Franciscus, Robert G; Larick, Roy R; Heizler, Matthew; Aswan; Eaves, K Lindsay; Marsh, Hannah E

2011-10-01

7

Gamma-ray spectrometric dating of late Homo erectus skulls from Ngandong and Sambungmacan, Central Java, Indonesia.  

PubMed

Hominid fossils from Ngandong and Sambungmacan, Central Java, Indonesia, are considered to be the most anatomically derived and youngest representatives of Homo erectus. Nondestructive gamma-ray spectrometric dating of three of these Homo erectus skulls showed that all samples underwent uranium leaching. Nevertheless, we could establish minimum age estimates of around 40ka, with an upper age limit of around 60 to 70ka. This means that the Homo erectus of Java very likely survived the Toba eruption and may have been contemporaneous with the earliest Homo sapiens in Southeast Asia and Australasia. PMID:18479734

Yokoyama, Yuji; Falguères, Christophe; Sémah, François; Jacob, Teuku; Grün, Rainer

2008-08-01

8

Thickened cranial vault and parasagittal keeling: correlated traits and autapomorphies of Homo erectus?  

PubMed

Homo erectus sensu lato (s.l.) is a key species in the hominin fossil record for the study of human evolution, being one of the first species discovered and perhaps the most documented, but also because of its long temporal range and having dispersed out of Africa earlier than any other human species. Here I test two proposed autapomorphic traits of H. erectus, namely the increased thickness of the upper cranial vault and parasagittal keeling. The definition of these two anatomical features and their expression and variation among hominids are discussed. The results of this study indicate that the upper vault in Asian H. erectus is not absolutely thicker compared with fossil anatomically modern Homo sapiens, whereas Broken Hill and Petralona have values above the range of variation of H. erectus. Moreover, this anatomical region in Asian H. erectus is not significantly thicker compared with Pan paniscus. In addition, these results demonstrate that cranial vault thickness should not be used to make hypotheses regarding sexual attribution of fossil hominin specimens. I also show that the relation between relief on the external surface of the upper vault, parasagittal keeling and bregmatic eminence, and bone thickness is complex. In this context, the autapomorphic status of the two analysed traits in H. erectus may be rejected. Nevertheless, different patterns in the distribution of bone thickness on the upper vault were identified. Some individual variations are visible, but specificities are observable in samples of different species. The pattern of bone thickness distribution observed in Asian H. erectus, P. paniscus, possibly australopiths, and early Homo or Homo ergaster/erectus appears to be shared by these different species and would be a plesiomorphic trait among hominids. In contrast, two apomorphic states for this feature were identified for Neandertals and H. sapiens. PMID:23541383

Balzeau, Antoine

2013-06-01

9

Taxonomic differences in deciduous upper second molar crown outlines of Homo sapiens, Homo neanderthalensis and Homo erectus.  

PubMed

A significant number of Middle to Late Pleistocene sites contain primarily (and sometimes only) deciduous teeth (e.g., Grotta del Cavallo, Mezmaiskaya, Blombos). Not surprisingly, there has been a recent renewed interest in deciduous dental variation, especially in the context of distinguishing Homo neanderthalensis and Homo sapiens. Most studies of the deciduous dentition of fossil hominins have focused on standard metrical variation but morphological (non-metric and morphometric) variation also promises to shed light on long standing taxonomic questions. This study examines the taxonomic significance of the crown outline of the deciduous upper second molar through principal components analysis and linear discriminant analysis. We examine whether or not the crown shape of the upper deciduous second molar separates H. neanderthalensis from H. sapiens and explore whether it can be used to correctly assign individuals to taxa. It builds on previous studies by focusing on crown rather than cervical outline and by including a large sample of geographically diverse recent human populations. Our samples include 17 H. neanderthalensis, five early H. sapiens, and 12 Upper Paleolithic H. sapiens. In addition, we include two Homo erectus specimens in order to evaluate the polarity of crown shape differences observed between H. neanderthalensis and H. sapiens. Our results show that crown outline shape discriminates H. sapiens and H. neanderthalensis quite well, but does not do well at distinguishing H. erectus from H. sapiens. We conclude that the crown outline shape observed in H. sapiens is a primitive retention and that the skewed shape observed in H. neanderthalensis is a derived condition. Finally, we explore the phylogenetic implications of the results for the H. erectus molars. PMID:24703186

Bailey, Shara E; Benazzi, Stefano; Souday, Caroline; Astorino, Claudia; Paul, Kathleen; Hublin, Jean-Jacques

2014-07-01

10

Early Homo erectus skeleton from west Lake Turkana, Kenya  

Microsoft Academic Search

The most complete early hominid skeleton ever found was discovered at Nariokotome III, west Lake Turkana, Kenya, and excavated in situ in sediments dated close to 1.6 Myr. The specimen, KNM-WT 15000, is a male Homo erectus that died at 12 +\\/- 1 years of age, as judged by human standards, but was already 1.68 m tall. Although human-like in

Frank Brown; John Harris; Richard Leakey; Alan Walker

1985-01-01

11

African Homo erectus: Old radiometric ages and young Oldowan assemblages in the middle Awash Valley, Ethiopia  

SciTech Connect

Fossils and artifacts recovered from the middle Awash Valley of Ethiopia's Afar depression sample the Middle Pleistocene transition from Homo erectus to Homo sapiens. Ar/Ar ages, biostratigraphy, and tephrachronology from this area indicate that the Pleistocene Bodo hominid cranium and newer specimens are approximately 0.6 million years old. Only Oldowan chopper and flake assemblages are present in the lower stratigraphic units but Acheulean bifacial artifacts are consistently prevalent and widespread in directly overlying deposits. This technological transition is related to a shift in sedimentary regime, supporting the hypothesis that Middle Pleistocene Oldowan assemblages represent a behavioral facies of the Acheulean industrial complex.

Clark, J.D.; White, T.D.; Selassie, Y.H. (Univ. of California, Berkeley, CA (United States)); Heinzelin, J. de (Institut Royal des Sciences Naturelles de Belgique, Brussels (Belgium)); Schick, K.D. (Indiana Univ., Bloomington, IN (United States)); Hart, W.K. (Miami Univ., Oxford, OH (United States)); WoldeGabriel, G. (Los Alamos National Lab., NM (United States)); Walter, R.C. (Institute of Human Origins, Berkeley, CA (United States)); Suwa, G. (Univ. of Tokyo (Japan)); Asfaw, B. (Addis Ababa (Ethiopia)) (and others)

1994-06-24

12

Solo man in question: Convergent views to split Indonesian Homo erectus in two categories  

Microsoft Academic Search

Between the famous Man of Java and the new star of paleoanthropology id est the Man of Flores, embedded in the bank of the river Solo or in the shadow of the volcanoes of Sangiran, Homo erectus remains apart. Driven from evolved Homo erectus to archaic Homo sapiens, for a long time Solo man did not find a real place

Valery Zeitoun; Florent Détroit; Dominique Grimaud-Hervé; Harry Widianto

2010-01-01

13

A new Homo erectus (Zhoukoudian V) brain endocast from China.  

PubMed

A new Homo erectus endocast, Zhoukoudian (ZKD) V, is assessed by comparing it with ZKD II, ZKD III, ZKD X, ZKD XI, ZKD XII, Hexian, Trinil II, Sambungmacan (Sm) 3, Sangiran 2, Sangiran 17, KNM-ER 3733, KNM-WT 15 000, Kabwe, Liujiang and 31 modern Chinese. The endocast of ZKD V has an estimated endocranial volume of 1140 ml. As the geological age of ZKD V is younger than the other ZKD H. erectus, evolutionary changes in brain morphology are evaluated. The brain size of the ZKD specimens increases slightly over time. Compared with the other ZKD endocasts, ZKD V shows important differences, including broader frontal and occipital lobes, some indication of fuller parietal lobes, and relatively large brain size that reflect significant trends documented in later hominin brain evolution. Bivariate and principal component analyses indicate that geographical variation does not characterize the ZKD, African and other Asian specimens. The ZKD endocasts share some common morphological and morphometric features with other H. erectus endocasts that distinguish them from Homo sapiens. PMID:19403532

Wu, Xiujie; Schepartz, Lynne A; Liu, Wu

2010-01-22

14

Paleoanthropology: Homo erectus and the limits of a paleontological species.  

PubMed

The bushy nature of the human evolutionary tree in the past 3 million years is widely accepted. Yet, a spectacular new fossil of early Homo has prompted some paleoanthropologists to prune our family tree. PMID:24456983

Hublin, Jean-Jacques

2014-01-20

15

Ecospaces occupied by Homo erectus and Homo sapiens in insular Southeast Asia in the Pleistocene  

NASA Astrophysics Data System (ADS)

Hominins migrated to the islands of the Sunda Shelf multiple times. At least two immigration events are evident, an early immigration of Homo erectus in the late Early Pleistocene and a second immigration of Homo sapiens during the Late Pleistocene. Regional environments changed considerably in the Pleistocene. Expansion patterns among hominins are at least co-determined by their ecologies and environmental change. We examine these expansion patterns on the basis of habitat reconstructions. Mammalian communities provide a geographically extensive record and permit to assess hominin ecospaces. Although chronological resolution is low, they represent the most complete record of habitat changes associated with hominin expansion patterns. In order to reconstruct and compare hominin ecospaces on a quantitative scale, we set up a reference sample consisting of mammalian communities of 117 national parks in South Asia and Sub-Saharan Africa. The diversity of such communities is assessed by ecological profiling of specialized herbivore taxa. Moreover, datasets on climate and vegetation correlate with the diversity structure of such specialized herbivore communities. Reconstructing the diversity structure of communities at key sites in Pleistocene Southeast Asia permits to infer features of the climatic and vegetation framework associated with different hominin taxa. Our results show that Homo erectus and Homo sapiens did not occupy similar ecospaces. The ecospace of Homo erectus is characterized by comparatively low diversity among frugivorous and folivorous taxa, while obligate grazers are part of the assemblages. Specialized herbivore communities with such a diversity structure occur at present in East Africa, while they are absent in Southeast Asia. In the reference sample, this type of ecospace corresponds to seasonal wetlands. Although Homo sapiens still inhabits this type of environment in Southeast Asia, his ecospace is wider. Homo sapiens is associated with specialized herbivore communities dominated by frugivorous and folivorous taxa. Specialized herbivore communities with such a diversity structure occur at present in rainforests on the Sunda Shelf.

Hertler, Christine; Haupt, Susanne; Volmer, Rebekka; Bruch, Angela

2014-05-01

16

Dating the Homo erectus bearing travertine from Kocaba? (Denizli, Turkey) at at least 1.1 Ma  

NASA Astrophysics Data System (ADS)

Since its discovery within a travertine quarry, the fragmentary cranium of the only known Turkish Homo erectus, the Kocaba? hominid, has led to conflicting biochronological estimations. First estimated to be ˜500 ka old, the partial skull presents a combination of archaic and evolved features that puts it as an intermediate specimen between the Dmanisi fossils (Homo georgicus) and the Chinese Zhoukoudian skulls (Homo erectus) respectively dated to 1.8 to ˜0.8 Ma. Here we present a multidisciplinary study combining sedimentological, paleontological and paleoanthropological observations together with cosmogenic nuclide concentration and paleomagnetic measurements to provide an absolute chronological framework for the Upper fossiliferous Travertine unit where the Kocaba? hominid and fauna were discovered. The 26Al/10Be burial ages determined on pebbles from conglomeratic levels framing the Upper fossiliferous Travertine unit, which exhibits an inverse polarity, constrains its deposition to before the Cobb Mountain sub-chron, that is between 1.22 and ˜1.5 Ma. The alternative match of the normal polarity recorded above the travertine with the Jaramillo subchron (lower limit 1.07 Ma) may also be marginally compatible with cosmogenic nuclides interpretation, thus the proposed minimum age of 1.1 Ma for the end of massive travertine deposition. The actual age of the fossils is likely to be in the 1.1-1.3 Ma range. This absolute date is in close agreement with the paleoanthropological conclusions based on morphometric comparisons implying that Kocaba? hominid belongs to the Homo erectus s.l. group that includes Chinese and African fossils, and is different from Middle and Upper Pleistocene specimens. Furthermore, this date is confirmed by the large mammal assemblage, typical of the late Villafranchian. Because it attests to the antiquity of human occupation of the Anatolian Peninsula and one of the waves of settlements out of Africa, this work challenges the current knowledge of the Homo erectus dispersal over Eurasia.

Lebatard, Anne-Elisabeth; Alçiçek, M. Cihat; Rochette, Pierre; Khatib, Samir; Vialet, Amélie; Boulbes, Nicolas; Bourlès, Didier L.; Demory, François; Guipert, Gaspard; Mayda, Serdar; Titov, Vadim V.; Vidal, Laurence; de Lumley, Henry

2014-03-01

17

Mojokerto revisited: evidence for an intermediate pattern of brain growth in Homo erectus.  

PubMed

Brain development in Homo erectus is a subject of great interest, and the infant calvaria from Mojokerto, Indonesia, has featured prominently in these debates. Some researchers have suggested that the pattern of brain development in H. erectus resembled that of non-human apes, while others argue for a more human-like growth pattern. In this study, we retested hypotheses regarding brain ontogeny in H. erectus using new methods (resampling), and data from additional H. erectus crania. Our results reveal that humans achieve 62% (±10%) and chimpanzees 80% (±9%) of their adult endocranial volume by 0.5-1.5 years of age. Using brain mass data, humans achieve on average 65% and chimpanzees 81% of adult size by 0.5-1.5 years. When compared with adult H. erectus crania (n = 9) from Indonesian sites greater than 1.2 million years old, Mojokerto had reached ?70% of its adult cranial capacity. Mojokerto thus falls almost directly between the average growth in humans and chimpanzees, and well within the range of both. We therefore suggest that brain development in H. erectus cannot be dichotomized as either ape-like or human-like; it was H. erectus-like. These data indicate that H. erectus may have had a unique developmental pattern that should be considered as an important step along the continuum of brain ontogeny between apes and humans. PMID:23815827

O'Connell, Caitlin A; DeSilva, Jeremy M

2013-08-01

18

Way out of Africa: Early Pleistocene paleoenvironments inhabited by Homo erectus in Sangiran, Java  

Microsoft Academic Search

A sequence of paleosols in the Solo Basin, Central Java, Indonesia, documents the local and regional environments present when Homo erectus spread through Southeast Asia during the early Pleistocene. The earliest human immigrants encountered a low-relief lake-margin landscape dominated by moist grasslands with open woodlands in the driest landscape positions. By 1.5Ma, large streams filled the lake and the landscape

E. Arthur Bettis; Adrianne K. Milius; Scott J. Carpenter; Roy Larick; Yahdi Zaim; Yan Rizal; Russell L. Ciochon; Stephanie A. Tassier-Surine; Daniel Murray; Suminto; Sutinko Bronto

2009-01-01

19

A calvarium of late Homo erectus from Ceprano, Italy  

Microsoft Academic Search

On 13 March 1994, a fragmented, incomplete and highly fossilized, human calvarium was discoveredin situby one of the authors (I.B.) during excavations for the construction of a highway near Ceprano, a town in southern Latium, situated about 55 miles S.E. from Rome. The remains come from a clay lying below sandy volcaniclastic gravels whose age is estimated by K–Ar to

A. Ascenzi; I. Biddittu; P. F. Cassoli; A. G. Segre; E. Segre-Naldini

1996-01-01

20

Hominid mandibular corpus shape variation and its utility for recognizing species diversity within fossil Homo.  

PubMed

Mandibular corpora are well represented in the hominin fossil record, yet few studies have rigorously assessed the utility of mandibular corpus morphology for species recognition, particularly with respect to the linear dimensions that are most commonly available. In this study, we explored the extent to which commonly preserved mandibular corpus morphology can be used to: (i) discriminate among extant hominid taxa and (ii) support species designations among fossil specimens assigned to the genus Homo. In the first part of the study, discriminant analysis was used to test for significant differences in mandibular corpus shape at different taxonomic levels (genus, species and subspecies) among extant hominid taxa (i.e. Homo, Pan, Gorilla, Pongo). In the second part of the study, we examined shape variation among fossil mandibles assigned to Homo (including H. habilis sensu stricto, H. rudolfensis, early African H. erectus/H. ergaster, late African H. erectus, Asian H. erectus, H. heidelbergensis, H. neanderthalensis and H. sapiens). A novel randomization procedure designed for small samples (and using group 'distinctness values') was used to determine whether shape variation among the fossils is consistent with conventional taxonomy (or alternatively, whether a priori taxonomic groupings are completely random with respect to mandibular morphology). The randomization of 'distinctness values' was also used on the extant samples to assess the ability of the test to recognize known taxa. The discriminant analysis results demonstrated that, even for a relatively modest set of traditional mandibular corpus measurements, we can detect significant differences among extant hominids at the genus and species levels, and, in some cases, also at the subspecies level. Although the randomization of 'distinctness values' test is more conservative than discriminant analysis (based on comparisons with extant specimens), we were able to detect at least four distinct groups among the fossil specimens (i.e. H. sapiens, H. heidelbergensis, Asian H. erectus and a combined 'African Homo' group consisting of H. habilis sensu stricto, H. rudolfensis, early African H. erectus/H. ergaster and late African H. erectus). These four groups appear to be distinct at a level similar to, or greater than, that of modern hominid species. In addition, the mandibular corpora of H. neanderthalensis could be distinguished from those of 'African Homo', although not from those of H. sapiens, H. heidelbergensis, or the Asian H. erectus group. The results suggest that the features most commonly preserved on the hominin mandibular corpus have some taxonomic utility, although they are unlikely to be useful in generating a reliable alpha taxonomy for early African members of the genus Homo. PMID:19094183

Lague, Michael R; Collard, Nicole J; Richmond, Brian G; Wood, Bernard A

2008-12-01

21

Hominid mandibular corpus shape variation and its utility for recognizing species diversity within fossil Homo  

PubMed Central

Mandibular corpora are well represented in the hominin fossil record, yet few studies have rigorously assessed the utility of mandibular corpus morphology for species recognition, particularly with respect to the linear dimensions that are most commonly available. In this study, we explored the extent to which commonly preserved mandibular corpus morphology can be used to: (i) discriminate among extant hominid taxa and (ii) support species designations among fossil specimens assigned to the genus Homo. In the first part of the study, discriminant analysis was used to test for significant differences in mandibular corpus shape at different taxonomic levels (genus, species and subspecies) among extant hominid taxa (i.e. Homo, Pan, Gorilla, Pongo). In the second part of the study, we examined shape variation among fossil mandibles assigned to Homo(including H. habilis sensu stricto, H. rudolfensis, early African H. erectus/H. ergaster, late African H. erectus, Asian H. erectus, H. heidelbergensis, H. neanderthalensis and H. sapiens). A novel randomization procedure designed for small samples (and using group ‘distinctness values’) was used to determine whether shape variation among the fossils is consistent with conventional taxonomy (or alternatively, whether a priori taxonomic groupings are completely random with respect to mandibular morphology). The randomization of ‘distinctness values’ was also used on the extant samples to assess the ability of the test to recognize known taxa. The discriminant analysis results demonstrated that, even for a relatively modest set of traditional mandibular corpus measurements, we can detect significant differences among extant hominids at the genus and species levels, and, in some cases, also at the subspecies level. Although the randomization of ‘distinctness values’ test is more conservative than discriminant analysis (based on comparisons with extant specimens), we were able to detect at least four distinct groups among the fossil specimens (i.e. H. sapiens, H. heidelbergensis, Asian H. erectus and a combined ‘African Homo’ group consisting of H. habilis sensu stricto, H. rudolfensis, early African H. erectus/H. ergaster and late African H. erectus). These four groups appear to be distinct at a level similar to, or greater than, that of modern hominid species. In addition, the mandibular corpora of H. neanderthalensis could be distinguished from those of ‘African Homo’, although not from those of H. sapiens, H. heidelbergensis, or the Asian H. erectus group. The results suggest that the features most commonly preserved on the hominin mandibular corpus have some taxonomic utility, although they are unlikely to be useful in generating a reliable alpha taxonomy for early African members of the genus Homo.

Lague, Michael R; Collard, Nicole J; Richmond, Brian G; Wood, Bernard A

2008-01-01

22

Growth processes in teeth distinguish modern humans from Homo erectus and earlier hominins  

Microsoft Academic Search

A modern human-like sequence of dental development, as a proxy for the pace of life history, is regarded as one of the diagnostic hallmarks of our own genus Homo. Brain size, age at first reproduction, lifespan and other life-history traits correlate tightly with dental development. Here we report differences in enamel growth that show the earliest fossils attributed to Homo

Christopher Dean; Meave G. Leakey; Donald Reid; Friedemann Schrenk; Gary T. Schwartz; Christopher Stringer; Alan Walker

2001-01-01

23

Evolution of the Genus Homo  

Microsoft Academic Search

Definition of the genus Homo is almost as fraught as the definition of Homo sapiens. We look at the evidence for ``early Homo,'' finding little morphological basis for extending our genus to any of the 2.5-1.6-myr-old fossil forms assigned to ``early Homo'' or Homo habilis\\/rudolfensis. We also point to heterogeneity among ``early African Homo erectus,'' and the lack of apomorphies

Ian Tattersall; Jeffrey H. Schwartz

2009-01-01

24

The age of the 20 meter Solo River terrace, Java, Indonesia and the survival of Homo erectus in Asia.  

PubMed

Homo erectus was the first human lineage to disperse widely throughout the Old World, the only hominin in Asia through much of the Pleistocene, and was likely ancestral to H. sapiens. The demise of this taxon remains obscure because of uncertainties regarding the geological age of its youngest populations. In 1996, some of us co-published electron spin resonance (ESR) and uranium series (U-series) results indicating an age as young as 35-50 ka for the late H. erectus sites of Ngandong and Sambungmacan and the faunal site of Jigar (Indonesia). If correct, these ages favor an African origin for recent humans who would overlap with H. erectus in time and space. Here, we report (40)Ar/(39)Ar incremental heating analyses and new ESR/U-series age estimates from the "20 m terrace" at Ngandong and Jigar. Both data sets are internally consistent and provide no evidence for reworking, yet they are inconsistent with one another. The (40)Ar/(39)Ar analyses give an average age of 546±12 ka (sd±5 se) for both sites, the first reliable radiometric indications of a middle Pleistocene component for the terrace. Given the technical accuracy and consistency of the analyses, the argon ages represent either the actual age or the maximum age for the terrace and are significantly older than previous estimates. Most of the ESR/U-series results are older as well, but the oldest that meets all modeling criteria is 143 ka+20/-17. Most samples indicated leaching of uranium and likely represent either the actual or the minimum age of the terrace. Given known sources of error, the U-series results could be consistent with a middle Pleistocene age. However, the ESR and (40)Ar/(39)Ar ages preclude one another. Regardless, the age of the sites and hominins is at least bracketed between these estimates and is older than currently accepted. PMID:21738710

Indriati, Etty; Swisher, Carl C; Lepre, Christopher; Quinn, Rhonda L; Suriyanto, Rusyad A; Hascaryo, Agus T; Grün, Rainer; Feibel, Craig S; Pobiner, Briana L; Aubert, Maxime; Lees, Wendy; Antón, Susan C

2011-01-01

25

The Age of the 20 Meter Solo River Terrace, Java, Indonesia and the Survival of Homo erectus in Asia  

PubMed Central

Homo erectus was the first human lineage to disperse widely throughout the Old World, the only hominin in Asia through much of the Pleistocene, and was likely ancestral to H. sapiens. The demise of this taxon remains obscure because of uncertainties regarding the geological age of its youngest populations. In 1996, some of us co-published electron spin resonance (ESR) and uranium series (U-series) results indicating an age as young as 35–50 ka for the late H. erectus sites of Ngandong and Sambungmacan and the faunal site of Jigar (Indonesia). If correct, these ages favor an African origin for recent humans who would overlap with H. erectus in time and space. Here, we report 40Ar/39Ar incremental heating analyses and new ESR/U-series age estimates from the “20 m terrace" at Ngandong and Jigar. Both data sets are internally consistent and provide no evidence for reworking, yet they are inconsistent with one another. The 40Ar/39Ar analyses give an average age of 546±12 ka (sd±5 se) for both sites, the first reliable radiometric indications of a middle Pleistocene component for the terrace. Given the technical accuracy and consistency of the analyses, the argon ages represent either the actual age or the maximum age for the terrace and are significantly older than previous estimates. Most of the ESR/U-series results are older as well, but the oldest that meets all modeling criteria is 143 ka+20/?17. Most samples indicated leaching of uranium and likely represent either the actual or the minimum age of the terrace. Given known sources of error, the U-series results could be consistent with a middle Pleistocene age. However, the ESR and 40Ar/39Ar ages preclude one another. Regardless, the age of the sites and hominins is at least bracketed between these estimates and is older than currently accepted.

Indriati, Etty; Swisher, Carl C.; Lepre, Christopher; Quinn, Rhonda L.; Suriyanto, Rusyad A.; Hascaryo, Agus T.; Grun, Rainer; Feibel, Craig S.; Pobiner, Briana L.; Aubert, Maxime; Lees, Wendy; Anton, Susan C.

2011-01-01

26

High-resolution record of the Matuyama-Brunhes transition constrains the age of Javanese Homo erectus in the Sangiran dome, Indonesia.  

PubMed

A detailed paleomagnetic study conducted in the Sangiran area, Java, has provided a reliable age constraint on hominid fossil-bearing formations. A reverse-to-normal polarity transition marks a 7-m thick section across the Upper Tuff in the Bapang Formation. The transition has three short reversal episodes and is overlain by a thick normal polarity magnetozone that was fission-track dated to the Brunhes chron. This pattern closely resembles another high-resolution Matuyama-Brunhes (MB) transition record in an Osaka Bay marine core. In the Sangiran sediments, four successive transitional polarity fields lie just below the presumed main MB boundary. Their virtual geomagnetic poles cluster in the western South Pacific, partly overlapping the transitional virtual geomagnetic poles from Hawaiian and Canary Islands' lavas, which have a mean (40)Ar/(39)Ar age of 776 ± 2 ka. Thus, the polarity transition is unambiguously the MB boundary. A revised correlation of tuff layers in the Bapang Formation reveals that the hominid last occurrence and the tektite level in the Sangiran area are nearly coincident, just below the Upper Middle Tuff, which underlies the MB transition. The stratigraphic relationship of the tektite level to the MB transition in the Sangiran area is consistent with deep-sea core data that show that the meteorite impact preceded the MB reversal by about 12 ka. The MB boundary currently defines the uppermost horizon yielding Homo erectus fossils in the Sangiran area. PMID:22106291

Hyodo, Masayuki; Matsu'ura, Shuji; Kamishima, Yuko; Kondo, Megumi; Takeshita, Yoshihiro; Kitaba, Ikuko; Danhara, Tohru; Aziz, Fachroel; Kurniawan, Iwan; Kumai, Hisao

2011-12-01

27

Diagnosing Homo sapiens in the fossil record.  

PubMed

Abstract Background: Diagnosing Homo sapiens is a critical question in the study of human evolution. Although what constitutes living members of our own species is straightforward, in the fossil record this is still a matter of much debate. The issue is complicated by questions of species diagnoses and ideas about the mode by which a new species is born, by the arguments surrounding the behavioural and cognitive separateness of the species, by the increasing appreciation of variation in the early African H. sapiens record and by new DNA evidence of hybridization with extinct species. Methods and results: This study synthesizes thinking on the fossils, archaeology and underlying evolutionary models of the last several decades with recent DNA results from both H. sapiens and fossil species. Conclusion: It is concluded that, although it may not be possible or even desirable to cleanly partition out a homogenous morphological description of recent H. sapiens in the fossil record, there are key, distinguishing morphological traits in the cranium, dentition and pelvis that can be usefully employed to diagnose the H. sapiens lineage. Increasing advances in retrieving and understanding relevant genetic data provide a complementary and perhaps potentially even more fruitful means of characterizing the differences between H. sapiens and its close relatives. PMID:24932746

Stringer, Christopher Brian; Buck, Laura Tabitha

2014-07-01

28

Evolution of the Genus Homo  

NASA Astrophysics Data System (ADS)

Definition of the genus Homo is almost as fraught as the definition of Homo sapiens. We look at the evidence for “early Homo,” finding little morphological basis for extending our genus to any of the 2.5-1.6-myr-old fossil forms assigned to “early Homo” or Homo habilis/rudolfensis. We also point to heterogeneity among “early African Homo erectus,” and the lack of apomorphies linking these fossils to the Asian Homo erectus group, a cohesive regional clade that shows some internal variation, including brain size increase over time. The first truly cosmopolitan Homo species is Homo heidelbergensis, known from Africa, Europe, and China following 600 kyr ago. One species sympatric with it included the >500-kyr-old Sima de los Huesos fossils from Spain, clearly distinct from Homo heidelbergensis and the oldest hominids assignable to the clade additionally containing Homo neanderthalensis. This clade also shows evidence of brain size expansion with time; but although Homo neanderthalensis had a large brain, it left no unequivocal evidence of the symbolic consciousness that makes our species unique. Homo sapiens clearly originated in Africa, where it existed as a physical entity before it began (also in that continent) to show the first stirrings of symbolism. Most likely, the biological underpinnings of symbolic consciousness were exaptively acquired in the radical developmental reorganization that gave rise to the highly characteristic osteological structure of Homo sapiens, but lay fallow for tens of thousands of years before being “discovered” by a cultural stimulus, plausibly the invention of language.

Tattersall, Ian; Schwartz, Jeffrey H.

2009-05-01

29

Origin and evolution of the genus Homo  

Microsoft Academic Search

It is remarkable that the taxonomy and phylogenetic relationships of the earliest known representatives of our own genus, Homo, remain obscure. Advances in techniques for absolute dating and reassessments of the fossils themselves have rendered untenable a simple unilineal model of human evolution, in which Homo habilis succeeded the australopithecines and then evolved via H. erectus into H. sapiens -

Bernard Wood

1992-01-01

30

Implications of new early Homo fossils from Ileret, east of Lake Turkana, Kenya  

Microsoft Academic Search

Sites in eastern Africa have shed light on the emergence and early evolution of the genus Homo. The best known early hominin species, H.habilis and H.erectus, have often been interpreted as time-successive segments of a single anagenetic evolutionary lineage. The case for this was strengthened by the discovery of small early Pleistocene hominin crania from Dmanisi in Georgia that apparently

F. Spoor; M. G. Leakey; P. N. Gathogo; F. H. Brown; S. C. Antón; I. McDougall; C. Kiarie; F. K. Manthi; L. N. Leakey

2007-01-01

31

Man the Fat Hunter: The Demise of Homo erectus and the Emergence of a New Hominin Lineage in the Middle Pleistocene (ca. 400 kyr) Levant  

Microsoft Academic Search

The worldwide association of H. erectus with elephants is well documented and so is the preference of humans for fat as a source of energy. We show that rather than a matter of preference, H. erectus in the Levant was dependent on both elephants and fat for his survival. The disappearance of elephants from the Levant some 400 kyr ago

Miki Ben-Dor; Avi Gopher; Israel Hershkovitz; Ran Barkai

2011-01-01

32

Man the Fat Hunter: The Demise of Homo erectus and the Emergence of a New Hominin Lineage in the Middle Pleistocene (ca. 400 kyr) Levant  

PubMed Central

The worldwide association of H. erectus with elephants is well documented and so is the preference of humans for fat as a source of energy. We show that rather than a matter of preference, H. erectus in the Levant was dependent on both elephants and fat for his survival. The disappearance of elephants from the Levant some 400 kyr ago coincides with the appearance of a new and innovative local cultural complex – the Levantine Acheulo-Yabrudian and, as is evident from teeth recently found in the Acheulo-Yabrudian 400-200 kyr site of Qesem Cave, the replacement of H. erectus by a new hominin. We employ a bio-energetic model to present a hypothesis that the disappearance of the elephants, which created a need to hunt an increased number of smaller and faster animals while maintaining an adequate fat content in the diet, was the evolutionary drive behind the emergence of the lighter, more agile, and cognitively capable hominins. Qesem Cave thus provides a rare opportunity to study the mechanisms that underlie the emergence of our post-erectus ancestors, the fat hunters.

Ben-Dor, Miki; Gopher, Avi; Hershkovitz, Israel; Barkai, Ran

2011-01-01

33

Phenetic Affinities of Plio-Pleistocene Homo Fossils from South Africa: Molar Cusp Proportions  

Microsoft Academic Search

As aptly observed by Aiello et al. (2000), any attempt to reconstruct human evolutionary history depends upon reliable hypotheses\\u000a pertaining to the species groups that are represented in the hominin fossil record. There has been a notable lack of consensus\\u000a regarding the species of Homo that are represented in the Plio-Pleistocene karst cave deposits of South Africa (Howell, 1978; Clarke,

Frederick E. Grine; Heather F. Smith; Christopher P. Heesy; Emma J. Smith

34

The Homo habitat niche: using the avian fossil record to depict ecological characteristics of Palaeolithic Eurasian hominins  

Microsoft Academic Search

Although hardly applied to human palaeoecology, bird fossils offer a unique opportunity for quantitative studies of the hominin habitat. Here we reconstruct the Homo habitat niche across a large area of the Palaearctic, based on a database of avian fauna for Pleistocene sites. Our results reveal a striking association between Homo and habitat mosaics. A mix of open savannah-type woodland,

Clive Finlayson; José Carrión; Kimberly Brown; Geraldine Finlayson; Antonio Sánchez-Marco; Darren Fa; Joaquín Rodríguez-Vidal; Santiago Fernández; Elena Fierro; Marco Bernal-Gómez; Francisco Giles-Pacheco

2011-01-01

35

Homo floresiensis: a cladistic analysis  

Microsoft Academic Search

The announcement of a new species, Homo floresiensis, a primitive hominin that survived until relatively recent times is an enormous challenge to paradigms of human evolution. Until this announcement, the dominant paradigm stipulated that: 1) only more derived hominins had emerged from Africa, and 2) H. sapiens was the only hominin since the demise of Homo erectus and Homo neanderthalensis. Resistance

Debbie Argue; Mike Morwood; Thomas Sutikna; Jatmiko; E. W. Saptomo

2009-01-01

36

Origin of the Genus Homo  

Microsoft Academic Search

The origin of the genus Homo in Africa signals the beginning of the shift from increasingly bipedal apes to primitive, large-brained, stone tool-making,\\u000a meat-eaters that traveled far and wide. This early part of the human genus is represented by three species: Homo habilis, Homo rudolfensis, and Homo erectus. H. habilis is known for retaining primitive features that link it to

Holly M. Dunsworth

2010-01-01

37

Bone strength and athletic ability in hominids: Ardipithecus ramidus to Homo sapiens  

NASA Astrophysics Data System (ADS)

A methodology for the evaluation of the athletic ability of animals based on the strength of their femur and their body mass is developed. The ability of the femur to resist bending stresses is determined by its midlength cross-sectional geometry, its length and the elastic properties of the mineral part of the bone. The animal's athletic ability, determined by a ``bone strength index,'' is limited by this femoral bending strength in relation to the loads on the femur. This analysis is applied to the fossil record for Homo sapiens, Homo neanderthalensis, Homo erectus, Homo habilis, Australopithecus afarensis and Ardipithecus ramidus. Evidence that the femoral bone strength index of modern Homo sapiens has weakened over the last 50,000 years is found.

Lee, Scott

2012-10-01

38

A fossil skull probably of the genus Homo from Sterkfontein, Transvaal.  

PubMed

A skull with numerous Homo features was discovered at Sterkfontein, near Krugersdorp, Transvaal, in August 1976. It stems from member 5 of the Sterkfontein Formation, with stone tools and with fauna pointing to an age of 2.0-1.5 Myr. The underlying member 4 contains Australopithecus africanus, no stone tools, and fauna dated 3.0-2.5 Myr. The new find supports the view that the Sterkfontein toolmaker was not the earlier A. africanus, but a later hominid related to Homo habilis. By a remarkable double coincidence, the first pieces of the new skull, Stw 53, were found on August 9, 1976, 40 years to the day after Robert Broom's first visit to Sterkfontein, while the last part came to light on August 17, the 40th anniversary of Broom's first discovery of a hominid cranium at Sterkfontein. Although most of the fragments were found in a decalcified pocket of cave earth, one large part of the calvaria was still present in the calcified wall of the pocket, thus establishing indisputably the provenance of the specimen. PMID:401951

Hughes, A R; Tobias, P V

1977-01-27

39

Human species and mating systems: Neandertal-Homo sapiens reproductive isolation and the archaeological and fossil records.  

PubMed

The present paper examined the assumption of strong reproductive isolation (RI) between Homo neanderthalensis and Homo sapiens, as well as the question of what form it might have taken, using insights from the parallel case of chimpanzee–bonobo hybridization. RI from hybrid sterility or inviability was thought unlikely based on the short separation-to-introgression timeline. The forms of RI that typically develop in primates have relatively short timelines (especially for partial implementation); they generally preclude mating or influence hybrid survival and reproduction in certain contexts, and they have the potential to skew introgression directionality. These RI barriers are also consistent with some interpretations of the archaeological and fossil records, especially when behavioral, cognitive, morphological, and genetic differences between the two human species are taken into consideration. Differences potentially influencing patterns of survival and reproduction include interspecies violence, Neandertal xenophobia, provisioning behavior, and ontogenetic, morphological, and behavioral differences affecting matters such as kin and mate recognition, infanticide, and sexual selection. These factors may have skewed the occurrence of interbreeding or the survival and reproduction of hybrids in a way that might at least partially explain the pattern of introgression. PMID:24344097

Overmann, Karenleigh; Coolidge, Frederick

2013-01-01

40

Early evidence of the genus Homo in East Asia.  

PubMed

The timing and route of the earliest dispersal from Africa to Eastern Asia are contentious topics in the study of early human evolution because Asian hominin fossil sites with precise age constraints are very limited. Here we report new high-resolution magnetostratigraphic results that place stringent age controls on excavated hominin incisors and stone tools from the Yuanmou Basin, southwest China. The hominin-bearing layer resides in a reverse polarity magnetozone just above the upper boundary of the Olduvai subchron, yielding an estimated age of 1.7Ma. The finding represents the age of the earliest documented presence of Homo, with affinities to Homo erectus, in mainland East Asia. This age estimate is roughly the same as for H. erectus in island Southeast Asia and immediately prior to the oldest archaeological evidence in northeast Asia. Mammalian fauna and pollen obtained directly from the hominin site indicate that the Yuanmou hominins lived in a varied habitat of open vegetation with patches of bushland and forest on an alluvial fan close to a lake or swamp. The age and location are consistent with a rapid southern migration route of initial hominin populations into Eastern Asia. PMID:18842287

Zhu, R X; Potts, R; Pan, Y X; Yao, H T; Lü, L Q; Zhao, X; Gao, X; Chen, L W; Gao, F; Deng, C L

2008-12-01

41

Fossil Skulls from Dmanisi: A Paleodeme Representing Earliest Homo in Eurasia  

Microsoft Academic Search

\\u000a The Plio-Pleistocene site of Dmanisi has yielded much evidence bearing on the morphology and behavior of the earliest hominins\\u000a from western Eurasia. Human remains, animal bones and stone artifacts were deposited at Dmanisi during a brief interval following\\u000a the close of the Olduvai Subchron (1.77 million years ago). The hominin fossils now include an adult braincase (D2280), the\\u000a partial skull

G. Philip Rightmire; David Lordkipanidze

42

Variations and asymmetries in regional brain surface in the genus Homo.  

PubMed

Paleoneurology is an important field of research within human evolution studies. Variations in size and shape of an endocast help to differentiate among fossil hominin species whereas endocranial asymmetries are related to behavior and cognitive function. Here we analyse variations of the surface of the frontal, parieto-temporal and occipital lobes among different species of Homo, including 39 fossil hominins, ten fossil anatomically modern Homo sapiens and 100 endocasts of extant modern humans. We also test for the possible asymmetries of these features in a large sample of modern humans and observe individual particularities in the fossil specimens. This study contributes important new information about the brain evolution in the genus Homo. Our results show that the general pattern of surface asymmetry for the different regional brain surfaces in fossil species of Homo does not seem to be different from the pattern described in a large sample of anatomically modern H. sapiens, i.e., the right hemisphere has a larger surface than the left, as do the right frontal, the right parieto-temporal and the left occipital lobes compared with the contra-lateral side. It also appears that Asian Homo erectus specimens are discriminated from all other samples of Homo, including African and Georgian specimens that are also sometimes included in that taxon. The Asian fossils show a significantly smaller relative size of the parietal and temporal lobes. Neandertals and anatomically modern H. sapiens, who share the largest endocranial volume of all hominins, show differences when considering the relative contribution of the frontal, parieto-temporal and occipital lobes. These results illustrate an original variation in the pattern of brain organization in hominins independent of variations in total size. The globularization of the brain and the enlargement of the parietal lobes could be considered derived features observed uniquely in anatomically modern H. sapiens. PMID:22542169

Balzeau, Antoine; Holloway, Ralph L; Grimaud-Hervé, Dominique

2012-06-01

43

Internal cranial features of the Mojokerto child fossil (East Java, Indonesia).  

PubMed

The island of Java, Indonesia, has produced a remarkable number of fossil hominid remains. One of the earliest specimens was found in Perning and consists of an almost complete calvaria belonging to a juvenile individual, known as the Mojokerto child (Perning I). Using computed tomography, this study details its endocranial features. The specimen is still filled with sediment, but its inner surface is well preserved, and we were able to reconstruct its endocranial features electronically. The Mojokerto endocast is the only cerebral evidence available for such a young Homo erectus individual. We provide an analytical description, make comparisons with endocasts of other fossil hominids and modern humans, and discuss its individual age and taxonomic affinities. The ontogenetic pattern indicated by the Mojokerto child suggests that the growth and development of the Homo erectus brain was different from that of modern humans. The earliest stages of development, as characterized by this individual, correspond to important supero-inferior expansion, and relative rounding of the cerebrum. The following stages differ from that of modern humans by marked antero-posterior flattening of the brain and particularly antero-posterior development of the frontal lobes, resulting in the adult H. erectus morphology. PMID:15927659

Balzeau, Antoine; Grimaud-Hervé, Dominique; Jacob, Teuku

2005-06-01

44

Subnasal morphological variation in fossil hominids: a reassessment based on new observations and recent developmental findings.  

PubMed

Quantitative and qualitative assessments of subnasal morphology in fossil hominids yield distinct patterns which have been used both to sort robust from nonrobust australopithecine taxa and to distinguish individual species. Recently, new developmental models have been applied to hominoid subnasal morphological variation. These studies require that certain features of the fossil hominid subnasal region, in particular the topography of the nasal cavity entrance and details of vomeral morphology, be reevaluated. This study does so for the robust and nonrobust australopithecines, early Homo (H. habilis/H. rudolfensis), and African H. erectus. Results reaffirm an overall similarity of the nonrobust Australopithecus subnasal morphological pattern with that of the chimpanzee. They further indicate that a vomeral insertion above the nasal surface of the premaxilla should be added to the list of traits characteristic of the robust australopithecine subnasal morphological pattern. Finally, reassessment of subnasal morphology in the early Homo and H. erectus samples from Africa suggest that these two taxa share a similar subnasal morphological pattern. This pattern consists of a smooth nasal cavity entrance, a horizontal nasal sill whose anterior edge is demarcated by a strong nasal crest, and a well-developed horizontal spine at the posterior edge of the nasal sill. Although none of the African fossil Homo specimens preserve a vomer, indirect evidence suggests that it would have inserted above the nasal sill. PMID:10813707

McCollum, M A

2000-06-01

45

Age and biostratigraphic significance of the Punung Rainforest Fauna, East Java, Indonesia, and implications for Pongo and Homo.  

PubMed

The Punung Fauna is a key component in the biostratigraphic sequence of Java. It represents the most significant faunal turnover on the island in the last 1.5 million years, when Stegodon and other archaic mammal species characteristic of earlier Faunal stages were replaced by a fully modern fauna that included rainforest-dependent species such as Pongo pygmaeus (orangutan). Here, we report the first numerical ages for the Punung Fauna obtained by luminescence and uranium-series dating of the fossil-bearing deposits and associated flowstones. The Punung Fauna contained in the dated breccia is of early Last Interglacial age (between 128+/-15 and 118+/-3 ka). This result has implications for the age of the preceding Ngandong Fauna, including Homo erectus remains found in the Ngandong Terrace, and for the timing of Homo sapiens arrival in Southeast Asia, in view of claims for a modern human tooth associated with the Punung breccia. PMID:17706269

Westaway, K E; Morwood, M J; Roberts, R G; Rokus, A D; Zhao, J-x; Storm, P; Aziz, F; van den Bergh, G; Hadi, P; Jatmiko; de Vos, J

2007-12-01

46

Evolution of M1 crown size and cusp proportions in the genus Homo.  

PubMed

Previous research into tooth crown dimensions and cusp proportions has proved to be a useful way to identify taxonomic differences in Pliocene and Pleistocene fossil hominins. The present study has identified changes in both M(1) crown size and cusp proportions within the genus Homo, with M(1) overall crown size reduction apparently occurring in two main stages. The first stage (a reduction of ca. 17%) is associated with the emergence of Homo ergaster and Homo erectus sensu stricto. The second stage (a reduction of ca. 10%) occurs in Homo sapiens, but the reduced modern human M(1) tooth crown size was only attained in Upper Paleolithic times. The absolute sizes of the individual cusps are highly positively correlated with overall crown size and dental reduction produces a reduction in the absolute size of each of the cusps. Most of the individual cusps scale isometrically with crown size, but the paracone shows a negative allometric relationship, indicating that the reduction in paracone size is less than in the other M(1) cusps. Thus, the phylogenetically oldest cusp in the upper molars also seems to be the most stable cusp (at least in the M(1)). The most striking change in M(1) cusp proportions is a change in the relative size of the areas of the paracone and metacone. The combination of a small relative paracone and a large relative metacone generally characterizes specimens attributed to early Homo, and the presence of this character state in Australopithecus and Paranthropus suggests it may represent the primitive condition for the later part of the hominin clade. In contrast, nearly all later Homo taxa, with the exception of Homo antecessor, show the opposite condition (i.e. a relatively large paracone and a relatively small metacone). This change in the relationship between the relative sizes of the paracone and metacone is related to an isometric reduction of the absolute size of the metacone. This metacone reduction occurs in the context of relative stability in the paracone as crown size decreases. Among later Homo taxa, both Homo heidelbergensis and Homo neanderthalensis show a further reduction of the metacone and an enlargement of the hypocone. Fossil and contemporary H. sapiens samples show a trend toward increasing the relative size of the protocone and decreasing the relative size of the hypocone. In Europe, modern human M(1) cusp proportions are essentially reached during the Upper Paleolithic. Although some variation was documented among the fossil taxa, we suggest that the relative size of the M(1) paracone and metacone areas may be useful for differentiating the earliest members of our genus from subsequent Homo species. PMID:19438761

Quam, Rolf; Bailey, Shara; Wood, Bernard

2009-05-01

47

8 Defining the Genus Homo  

Microsoft Academic Search

The definition of the genus Homo is an important but under-researched topic. In this chapter, we show that interpretations of Homo have changed greatly over the last 150 years as a result of the incorporation of new fossil species, the discovery of fossil evidence that changed our perceptions of its component species, and reassessments of the functional capabilities of species

Mark Collard; Bernard Wood

48

Systematic assessment of a maxilla of Homo from Hadar, Ethiopia.  

PubMed

The Hadar site in Ethiopia is a prolific source of hominid fossils attributed to the species Australopithecus afarensis, which spans the period 3.4-3.0 million years (myr) in the Sidi Hakoma, Denen Dora and lower Kada Hadar Members of the Hadar Formation. Since 1992 a major focus of field work conducted at Hadar has centered on sediments younger than 3.0 myr, comprising the bulk of the Kada Hadar Member. Witnessing the rise of the "robust" Australopithecus clade(s), the origin of Homo, and the first record of lithic artifacts, the period between 3.0 and 2.0 myr is strategically vital for paleoanthropology. However, in eastern Africa it is a particularly poorly sampled temporal interval. This paper provides a detailed comparative description of a hominid maxilla with partial dentition found at Hadar in 1994. The specimen, A.L. 666-1, derives from a lithic artifact-bearing horizon high in the Kada Hadar Member, 0.8 m below the BKT-3 tephra, dated by the 40Ar/39Ar method to 2.33 +/- 0.07 myr. Our preliminary investigation of the hominid specimen showed unambiguous affinities with early representatives of the Homo clade (Kimbel et al. [1996] J. Hum. Evol. 31:549-561). Further studies on maxillary and dental morphology lead us to attribute A.L. 666-1 to Homo aff. H. habilis. The new Hadar jaw is the first paleontological evidence for the projection of the H. habilis maxillofacial morphotype well back into the Pliocene. It may represent a male of this species, whose maxillary hypodigm consists chiefly of females. A subsidiary finding of our study is that of the three earliest recorded species of Homo (H. habilis, H. rudolfensis, H. erectus), it is H. habilis that exhibits facial morphology closest to that expected in their last common ancestor. PMID:9209580

Kimbel, W H; Johanson, D C; Rak, Y

1997-06-01

49

Dental Evidence for Diets of Early Homo  

Microsoft Academic Search

The evolution of diet in the earliest members of our genus, Homo rudolfensis, H. habilis and H. erectus has received increased attention over the past few years (see Ungar et al., 2006a for review). Many models have been constructed,\\u000a based largely on nutritional studies combined with direct analogy (with living peoples or non-human primates) or on contextual\\u000a evidence, such as

Peter S. Ungar; Robert S. Scott

50

Cladistic analysis of early Homo crania from Swartkrans and Sterkfontein, South Africa  

Microsoft Academic Search

The phylogenetic relationships of early Pleistocene Homo crania from the South African sites of Swartkrans and Sterkfontein were investigated through cladistic analyses of 99 morphological characters. The Swartkrans Member 1 specimen SK 847 and the Stw 53 cranium from Sterkfontein Member 5A were treated as separate operational taxonomic units (OTUs), distinct from the three species of early Homo—H. erectus, H.

Heather F. Smith; Frederick E. Grine

2008-01-01

51

The Origin of Homo  

Microsoft Academic Search

Despite a steady increase in the number and diversity of African Middle Pliocene hominin fossils, paleoanthropolo-gists are\\u000a not now substantially closer to understanding the temporal, geographical or ecological contexts of the origin of the Homo clade than was the case in 1964, when Louis Leakey, Phillip Tobias and John Napier introduced Homo habilis as the earliest species of the human

William H. Kimbel

52

Homo floresiensis: a cladistic analysis.  

PubMed

The announcement of a new species, Homo floresiensis, a primitive hominin that survived until relatively recent times is an enormous challenge to paradigms of human evolution. Until this announcement, the dominant paradigm stipulated that: 1) only more derived hominins had emerged from Africa, and 2) H. sapiens was the only hominin since the demise of Homo erectus and Homo neanderthalensis. Resistance to H. floresiensis has been intense, and debate centers on two sets of competing hypotheses: 1) that it is a primitive hominin, and 2) that it is a modern human, either a pygmoid form or a pathological individual. Despite a range of analytical techniques having been applied to the question, no resolution has been reached. Here, we use cladistic analysis, a tool that has not, until now, been applied to the problem, to establish the phylogenetic position of the species. Our results produce two equally parsimonious phylogenetic trees. The first suggests that H. floresiensis is an early hominin that emerged after Homo rudolfensis (1.86Ma) but before H. habilis (1.66Ma, or after 1.9Ma if the earlier chronology for H. habilis is retained). The second tree indicates H. floresiensis branched after Homo habilis. PMID:19628252

Argue, D; Morwood, M J; Sutikna, T; Jatmiko; Saptomo, E W

2009-11-01

53

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

54

Mandibular shape analysis in fossil hominins: Fourier descriptors in norma lateralis.  

PubMed

Biological shape can be defined as the boundary of a form in 2-space (R(2)). An earlier study (Lestrel et al., 2010, HOMO-J. Comp. Hum. Biol.) of the cranial vault found that there were statistically significant differences between each of the three groups: H. erectus, H. heidelbergensis, and H. neanderthalensis compared with H. sapiens. In contrast, there was no statistically significant difference among the first three groups. These results suggest that these three groups may have formed single evolving lineage while H. sapiens represents a separate evolutionary development. The purpose of the current research was to discern if the mandible reflected a similar pattern as the cranial vault data. This study used lateral jpeg images of the mandible. Five fossil samples were used: A. robustus (n=7), H. erectus (n=12), H. heidelbergensis (n=4), H. neanderthalensis (n=22) and H. sapiens (n=61). Each mandible image was pre-processed with Photoshop Elements. Each image was then submitted to a specially written routine that digitized the 84 points along the mandible boundary. Each mandible was fitted with elliptical Fourier functions (EFFs). Procrustes superimposition was imposed to insure minimum shape differences. The mandible results largely mirrored the earlier cranial vault study with one exception. Statistically significant results were obtained for the mandible between the H. erectus and H. neanderthalensis samples in contrast to the earlier cranial vault data. F-tests disclosed that the statistical significance was limited to the anterior symphysis of the mandible. This mosaic pattern may be explained by the reduction in prognathism with the concomitant if rudimentary development of the chin as seen in H. neanderthalensis compared to H. erectus. PMID:23769600

Lestrel, P E; Wolfe, C A; Bodt, A

2013-08-01

55

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!!

61

A comprehensive morphometric analysis of the frontal and zygomatic bone of the Zuttiyeh fossil from Israel.  

PubMed

The Zuttiyeh hominin craniofacial fossil was discovered in Israel in 1925. Radiometric dates and the archaeological context (Acheulo-Yabrudian) bracket the associated cave layers to between 200 and 500 ka (thousands of years ago), making it one of the earliest cranial fossils discovered in the Near East thus far. Its geographic position, at the corridor between Africa and Eurasia, in combination with its probable Middle Pleistocene date make it a crucial specimen for interpreting later human evolution. Since its discovery, qualitative descriptive and traditional morphometric methods have variously suggested affinities to Homo erectus (Zhoukoudian), Homo neanderthalensis (Tabun), and early Homo sapiens (Skhul and Qafzeh). To better determine the taxonomic affinities of the Zuttiyeh fossil, this study uses 3D semilandmark geometric morphometric techniques and multivariate statistical analyses to quantify the frontal and zygomatic region and compare it with other Middle to Late Pleistocene African and Eurasian hominins. Our results show that the frontal and zygomatic morphology of Zuttiyeh is most similar to Shanidar 5, a Near East Neanderthal, Arago 21, a European Middle Pleistocene hominin, and Skhul 5, an early H. sapiens. The shape differences between archaic hominins (i.e., Homo heidelbergensis and H. neanderthalensis) in this anatomical region are very subtle. We conclude that Zuttiyeh exhibits a generalized frontal and zygomatic morphology, possibly indicative of the population that gave rise to modern humans and Neanderthals. However, given that it most likely postdates the split between these two lineages, Zuttiyeh might also be an early representative of the Neanderthal lineage. Neanderthals largely retained this generalized overall morphology, whereas recent modern humans depart from this presumably ancestral morphology. PMID:22176924

Freidline, S E; Gunz, P; Jankovi?, I; Harvati, K; Hublin, J J

2012-02-01

62

New magnetostratigraphy for the Olduvai Subchron in the Koobi Fora Formation, northwest Kenya, with implications for early Homo  

NASA Astrophysics Data System (ADS)

A problematic magnetostratigraphy for the Koobi Fora Formation has contributed to debates on the evolutionary implications for early hominin fossils. To address this, 50 independent samples distributed over a nearly 63-m-thick interval were collected from the lower-middle KBS Member type section in fossil collection Area 102, northeast Turkana Basin. Characteristic directions obtained by thermal demagnetization define a coherent magnetostratigraphy that is supported by alternating-field studies on 28 sister specimens and the prior tephrochronological framework. Two long polarity intervals were recognized, each 30-40 m in thickness, and interpreted as the upper part of the normal polarity Olduvai Subchron and the overlying reverse polarity Matuyama Chron. The end Olduvai consists of a normal-reverse-normal polarity sequence occurring over a thickness of at least 1 m but perhaps up to 5 m, suggesting that this subchron has a short reverse interval in its uppermost part. Such a fine-scale structure also has been reported from several other sites, like the Pliocene-Pleistocene boundary and point stratotype section at Vrica, Italy, which serves as a basis for formally delimiting three temporally discrete polarity subintervals for the Olduvai Subchron. These paleomagnetic results that place the upper boundary of the Olduvai at ˜ 48 m above the base of the KBS Member, coupled with published radioisotopic dates, firmly secure the age of partial cranium KNM-ER 3733 in the interval 1.78-1.48 Ma, with an interpolated age of ˜ 1.7 Ma, giving this fossil the most unambiguous numerical-age constraints, as compared to the oldest Homo cranial remains from Europe and Asia. Nonetheless, assured placement of the top of the Olduvai Subchron in the KBS Member is not sufficient in the face of other uncertainties to influence conventional interpretations of the timing and direction for the global dispersal of early Homo erectus.

Lepre, Christopher J.; Kent, Dennis V.

2010-02-01

63

Pleistocene Homo sapiens from Middle Awash, Ethiopia  

Microsoft Academic Search

The origin of anatomically modern Homo sapiens and the fate of Neanderthals have been fundamental questions in human evolutionary studies for over a century. A key barrier to the resolution of these questions has been the lack of substantial and accurately dated African hominid fossils from between 100,000 and 300,000 years ago. Here we describe fossilized hominid crania from Herto,

Tim D. White; Berhane Asfaw; David DeGusta; Henry Gilbert; Gary D. Richards; Gen Suwa; F. Clark Howell

2003-01-01

64

From Homo Economicus to Homo Sapiens  

Microsoft Academic Search

In responding to a request for predictions about the future of economics, I predict that Homo Economicus will evolve into Homo Sapiens, or, more simply put, economics will become more related to human behavior. My specific predictions are that Homo Economicus will start to lose IQ, will become a slower learner, will start interacting with other species, and that economists

Richard H. Thaler

2000-01-01

65

Phylogenetic rate shifts in feeding time during the evolution of Homo.  

PubMed

Unique among animals, humans eat a diet rich in cooked and nonthermally processed food. The ancestors of modern humans who invented food processing (including cooking) gained critical advantages in survival and fitness through increased caloric intake. However, the time and manner in which food processing became biologically significant are uncertain. Here, we assess the inferred evolutionary consequences of food processing in the human lineage by applying a Bayesian phylogenetic outlier test to a comparative dataset of feeding time in humans and nonhuman primates. We find that modern humans spend an order of magnitude less time feeding than predicted by phylogeny and body mass (4.7% vs. predicted 48% of daily activity). This result suggests that a substantial evolutionary rate change in feeding time occurred along the human branch after the human-chimpanzee split. Along this same branch, Homo erectus shows a marked reduction in molar size that is followed by a gradual, although erratic, decline in H. sapiens. We show that reduction in molar size in early Homo (H. habilis and H. rudolfensis) is explicable by phylogeny and body size alone. By contrast, the change in molar size to H. erectus, H. neanderthalensis, and H. sapiens cannot be explained by the rate of craniodental and body size evolution. Together, our results indicate that the behaviorally driven adaptations of food processing (reduced feeding time and molar size) originated after the evolution of Homo but before or concurrent with the evolution of H. erectus, which was around 1.9 Mya. PMID:21873223

Organ, Chris; Nunn, Charles L; Machanda, Zarin; Wrangham, Richard W

2011-08-30

66

Phylogenetic rate shifts in feeding time during the evolution of Homo  

PubMed Central

Unique among animals, humans eat a diet rich in cooked and nonthermally processed food. The ancestors of modern humans who invented food processing (including cooking) gained critical advantages in survival and fitness through increased caloric intake. However, the time and manner in which food processing became biologically significant are uncertain. Here, we assess the inferred evolutionary consequences of food processing in the human lineage by applying a Bayesian phylogenetic outlier test to a comparative dataset of feeding time in humans and nonhuman primates. We find that modern humans spend an order of magnitude less time feeding than predicted by phylogeny and body mass (4.7% vs. predicted 48% of daily activity). This result suggests that a substantial evolutionary rate change in feeding time occurred along the human branch after the human–chimpanzee split. Along this same branch, Homo erectus shows a marked reduction in molar size that is followed by a gradual, although erratic, decline in H. sapiens. We show that reduction in molar size in early Homo (H. habilis and H. rudolfensis) is explicable by phylogeny and body size alone. By contrast, the change in molar size to H. erectus, H. neanderthalensis, and H. sapiens cannot be explained by the rate of craniodental and body size evolution. Together, our results indicate that the behaviorally driven adaptations of food processing (reduced feeding time and molar size) originated after the evolution of Homo but before or concurrent with the evolution of H. erectus, which was around 1.9 Mya.

Organ, Chris; Nunn, Charles L.; Machanda, Zarin; Wrangham, Richard W.

2011-01-01

67

Cladistic analysis of early Homo crania from Swartkrans and Sterkfontein, South Africa.  

PubMed

The phylogenetic relationships of early Pleistocene Homo crania from the South African sites of Swartkrans and Sterkfontein were investigated through cladistic analyses of 99 morphological characters. The Swartkrans Member 1 specimen SK 847 and the Stw 53 cranium from Sterkfontein Member 5A were treated as separate operational taxonomic units (OTUs), distinct from the three species of early Homo-H. erectus, H. habilis, and H. rudolfensis-that are recognized from the Plio-Pleistocene deposits of East Africa. The cladistic analyses differed in the treatment of the South African OTUs (separate Swartkrans and Sterkfontein OTUs vs. a single Swartkrans+Sterkfontein OTU). PAUP 4.0 was used to construct cladograms and address hypotheses about relationships. In the analysis that treated the South African specimens as a single OTU, the position of that OTU was stable as a separate branch on the Homo clade between H. rudolfensis and [H. habilis+(H. erectus+H. sapiens)]. When SK 847 and Stw 53 were treated as separate OTUs, the majority of most parsimonious trees indicated that they were positioned in similar positions as the combined South African Homo OTU; that is, as separate branches between H. rudolfensis and [H. habilis+(H. erectus+H. sapiens)], with the Swartkrans OTU generally occupying a more derived position. The position of the Sterkfontein OTU was more stable than that of the Swartkrans OTU, which was found in several other positions among the minimum length trees. Running the analyses with only those characters preserved by SK 847 and Stw 53 resulted in similar topologies for minimum length trees, although the positions of Stw 53, SK 847, and H. habilis exchanged places in some trees. In no case was an exclusive sister relationship between either South African OTU and a particular species of Homo supported statistically. Both South African OTUs differ from H. habilis in the fewest number of cladistic characters. PMID:18289640

Smith, Heather F; Grine, Frederick E

2008-05-01

68

Wild chimpanzee dentition and its implications for assessing life history in immature hominin fossils  

Microsoft Academic Search

Data from three African field sites on Pan troglodytes demonstrate an unambiguous pattern of a slower growth rate in wild vs. captive chimpanzee populations. A revised dental growth chronology for chimpanzees is similar to estimated timing of Homo erectus and therefore has implications for interpreting life history in hominins.

Adrienne Zihlman; Debra Bolter; Christophe Boesch

2004-01-01

69

Postcranial evidence from early Homo from Dmanisi, Georgia  

Microsoft Academic Search

The Plio-Pleistocene site of Dmanisi, Georgia, has yielded a rich fossil and archaeological record documenting an early presence of the genus Homo outside Africa. Although the craniomandibular morphology of early Homo is well known as a result of finds from Dmanisi and African localities, data about its postcranial morphology are still relatively scarce. Here we describe newly excavated postcranial material

David Lordkipanidze; Tea Jashashvili; Abesalom Vekua; Marcia S. Ponce de León; Christoph P. E. Zollikofer; G. Philip Rightmire; Herman Pontzer; Reid Ferring; Oriol Oms; Martha Tappen; Maia Bukhsianidze; Jordi Agusti; Ralf Kahlke; Gocha Kiladze; Bienvenido Martinez-Navarro; Alexander Mouskhelishvili; Medea Nioradze; Lorenzo Rook

2007-01-01

70

Earliest Homo Sapiens Fossils Discovered in Ethiopia  

NSF Publications Database

... and show that near-humans had evolved in Africa long before the European neanderthals disappeared ... supports the "Out of Africa" hypothesis that modern humans evolved in Africa and not in multiple ...

71

Craniometric ratios of microcephaly and LB1, Homo floresiensis, using MRI and endocasts  

PubMed Central

The designation of Homo floresiensis as a new species derived from an ancient population is controversial, because the type specimen, LB1, might represent a pathological microcephalic modern Homo sapiens. Accordingly, two specific craniometric ratios (relative frontal breadth and cerebellar protrusion) were ascertained in 21 microcephalic infants and children by using MRI. Data on 118 age-equivalent control (normocephalic) subjects were collected for comparative purposes. In addition, the same craniometric ratios were determined on the endocasts of 10 microcephalic individuals, 79 normal controls (anatomically modern humans), and 17 Homo erectus specimens. These ratios were then compared with those of two LB1 endocasts. The findings showed that the calculated cerebral/cerebellar ratios of the LB1 endocast [Falk D, et al. (2007) Proc Natl Acad Sci USA 104:2513–2518] fall outside the range of living normocephalic individuals. The ratios derived from two LB1 endocasts also fall largely outside the range of modern normal human and H. erectus endocasts and within the range of microcephalic endocasts. The findings support but do not prove the contention that LB1 represents a pathological microcephalic Homo sapiens rather than a new species, (i.e., H. floresiensis).

Vannucci, Robert C.; Barron, Todd F.; Holloway, Ralph L.

2011-01-01

72

Cytogenetic and Nuclear DNA Content Characterization of Diploid Bromus erectus and Bromus variegatus  

Microsoft Academic Search

Bromus erectus Huds. (erect brome) and B. variegatus M. Bieb. are Eurasian Bromus species that have been tentatively identified as potential progenitors of smooth bromegrass (B. inermis Leyss) which is the principal cultivated bromegrass in North America. The objective of this study was to characterize the genome of diploid accessions of B. erectus (2n 5 2x 5 14) and B.

Metin Tuna; Kenneth P. Vogel; K. Arumuganathan

2006-01-01

73

Stratigraphic, chronological and behavioural contexts of Pleistocene Homo sapiens from Middle Awash, Ethiopia  

Microsoft Academic Search

Clarifying the geographic, environmental and behavioural contexts in which the emergence of anatomically modern Homo sapiens occurred has proved difficult, particularly because Africa lacked adequate geochronological, palaeontological and archaeological evidence. The discovery of anatomically modern Homo sapiens fossils at Herto, Ethiopia, changes this. Here we report on stratigraphically associated Late Middle Pleistocene artefacts and fossils from fluvial and lake margin

J. Desmond Clark; Yonas Beyene; Giday WoldeGabriel; William K. Hart; Paul R. Renne; Henry Gilbert; Alban Defleur; Gen Suwa; Shigehiro Katoh; Kenneth R. Ludwig; Jean-Renaud Boisserie; Berhane Asfaw; Tim D. White

2003-01-01

74

Brain size of Homo floresiensis and its evolutionary implications  

PubMed Central

The extremely small endocranial volume (ECV) of LB1, the type specimen of Homo floresiensis, poses a challenge in our understanding of human brain evolution. Some researchers hypothesize dramatic dwarfing of relative brain size from Homo erectus presumably without significant decrease in intellectual function, whereas others expect a lesser degree of brain diminution from a more primitive, small-brained form of hominin currently undocumented in eastern Asia. However, inconsistency in the published ECVs for LB1 (380–430 cc), unclear human intraspecific brain–body size scaling and other uncertainties have hampered elaborative modelling of its brain size reduction. In this study, we accurately determine the ECV of LB1 using high-resolution micro-CT scan. The ECV of LB1 thus measured, 426 cc, is larger than the commonly cited figure in previous studies (400 cc). Coupled with brain–body size correlation in Homo sapiens calculated based on a sample from 20 worldwide modern human populations, we construct new models of the brain size reduction in the evolution of H. floresiensis. The results show a more significant contribution of scaling effect than previously claimed.

Kubo, Daisuke; Kono, Reiko T.; Kaifu, Yousuke

2013-01-01

75

Variation in enamel thickness within the genus Homo.  

PubMed

Recent humans and their fossil relatives are classified as having thick molar enamel, one of very few dental traits that distinguish hominins from living African apes. However, little is known about enamel thickness in the earliest members of the genus Homo, and recent studies of later Homo report considerable intra- and inter-specific variation. In order to assess taxonomic, geographic, and temporal trends in enamel thickness, we applied micro-computed tomographic imaging to 150 fossil Homo teeth spanning two million years. Early Homo postcanine teeth from Africa and Asia show highly variable average and relative enamel thickness (AET and RET) values. Three molars from South Africa exceed Homo AET and RET ranges, resembling the hyper thick Paranthropus condition. Most later Homo groups (archaic European and north African Homo, and fossil and recent Homo sapiens) possess absolutely and relatively thick enamel across the entire dentition. In contrast, Neanderthals show relatively thin enamel in their incisors, canines, premolars, and molars, although incisor AET values are similar to H. sapiens. Comparisons of recent and fossil H. sapiens reveal that dental size reduction has led to a disproportionate decrease in coronal dentine compared with enamel (although both are reduced), leading to relatively thicker enamel in recent humans. General characterizations of hominins as having 'thick enamel' thus oversimplify a surprisingly variable craniodental trait with limited taxonomic utility within a genus. Moreover, estimates of dental attrition rates employed in paleodemographic reconstruction may be biased when this variation is not considered. Additional research is necessary to reconstruct hominin dietary ecology since thick enamel is not a prerequisite for hard-object feeding, and it is present in most later Homo species despite advances in technology and food processing. PMID:22361504

Smith, Tanya M; Olejniczak, Anthony J; Zermeno, John P; Tafforeau, Paul; Skinner, Matthew M; Hoffmann, Almut; Radov?i?, Jakov; Toussaint, Michel; Kruszynski, Robert; Menter, Colin; Moggi-Cecchi, Jacopo; Glasmacher, Ulrich A; Kullmer, Ottmar; Schrenk, Friedemann; Stringer, Chris; Hublin, Jean-Jacques

2012-03-01

76

Megadontia, striae periodicity and patterns of enamel secretion in Plio-Pleistocene fossil hominins.  

PubMed

Early hominins formed large and thick-enamelled cheek-teeth within relatively short growth periods as compared with modern humans. To understand better the developmental basis of this process, we measured daily enamel increments, or cross striations, in 17 molars of Plio-Pleistocene hominins representing seven different species, including specimens attributed to early Homo. Our results show considerable variation across species, although all specimens conformed to the known pattern characterised by greater values in outer than inner enamel, and greater cuspal than cervical values. We then compared our results with the megadontia index, which represents tooth size in relation to body mass, for each species to assess the effect of daily growth rates on tooth size. Our results indicate that larger toothed (megadont) taxa display higher rates or faster forming enamel than smaller toothed hominins. By forming enamel quickly, large tooth crowns were able to develop within the constraints of shorter growth periods. Besides daily increments, many animals express long-period markings (striae of Retzius) in their enamel. We report periodicity values (number of cross striations between adjacent striae) in 14 new specimens of Australopithecus afarensis, Paranthropus aethiopicus, Paranthropus boisei, Homo habilis, Homo rudolfensis and Homo erectus, and show that long-period striae express a strong association with male and average male-female body mass. Our results for Plio-Pleistocene hominins show that the biological rhythms that give rise to long-period striae are encompassed within the range of variation known for modern humans, but show a lower mean and modal value of 7 days in australopithecines. In our sample of early Homo, mean and modal periodicity values were 8 days, and therefore similar to modern humans. These new data on daily rates of enamel formation and periodicity provide a better framework to interpret surface manifestations of internal growth markings on fossil hominin tooth crowns. Importantly, our data on early hominin cross striation variation may now contribute towards solving difficult taxonomic diagnoses where much may depend on fragmentary molar remains and enamel structure. PMID:19172730

Lacruz, Rodrigo S; Dean, M Christopher; Ramirez-Rozzi, Fernando; Bromage, Timothy G

2008-08-01

77

Megadontia, striae periodicity and patterns of enamel secretion in Plio-Pleistocene fossil hominins  

PubMed Central

Early hominins formed large and thick-enamelled cheek-teeth within relatively short growth periods as compared with modern humans. To understand better the developmental basis of this process, we measured daily enamel increments, or cross striations, in 17 molars of Plio-Pleistocene hominins representing seven different species, including specimens attributed to early Homo. Our results show considerable variation across species, although all specimens conformed to the known pattern characterised by greater values in outer than inner enamel, and greater cuspal than cervical values. We then compared our results with the megadontia index, which represents tooth size in relation to body mass, for each species to assess the effect of daily growth rates on tooth size. Our results indicate that larger toothed (megadont) taxa display higher rates or faster forming enamel than smaller toothed hominins. By forming enamel quickly, large tooth crowns were able to develop within the constraints of shorter growth periods. Besides daily increments, many animals express long-period markings (striae of Retzius) in their enamel. We report periodicity values (number of cross striations between adjacent striae) in 14 new specimens of Australopithecus afarensis, Paranthropus aethiopicus, Paranthropus boisei, Homo habilis, Homo rudolfensis and Homo erectus, and show that long-period striae express a strong association with male and average male–female body mass. Our results for Plio-Pleistocene hominins show that the biological rhythms that give rise to long-period striae are encompassed within the range of variation known for modern humans, but show a lower mean and modal value of 7 days in australopithecines. In our sample of early Homo, mean and modal periodicity values were 8 days, and therefore similar to modern humans. These new data on daily rates of enamel formation and periodicity provide a better framework to interpret surface manifestations of internal growth markings on fossil hominin tooth crowns. Importantly, our data on early hominin cross striation variation may now contribute towards solving difficult taxonomic diagnoses where much may depend on fragmentary molar remains and enamel structure.

Lacruz, Rodrigo S; Dean, M Christopher; Ramirez-Rozzi, Fernando; Bromage, Timothy G

2008-01-01

78

Is Homo heidelbergensis a distinct species? New insight on the Mauer mandible  

Microsoft Academic Search

The discovery of new fossils in Africa, Asia, and Europe, and the recognition of a greater diversity in the middle Pleistocene fossil record, has led to a reconsideration of the species Homo heidelbergensis. This nomen, formulated by Schoetensack in 1908 to describe the Mauer jaw (Germany), was almost forgotten during most of the past century. Numerous fossils have been attributed

Aurélien Mounier; François Marchal; Silvana Condemi

2009-01-01

79

A revision of the Dubois crocodylians, Gavialis bengawanicus and Crocodylus ossifragus, from the Pleistocene Homo erectus beds of Java  

Microsoft Academic Search

Revision of the two extinct Javanese crocodylian species Gavialis bengawanicusDubois, 1908, and Crocodylus ossifragusDubois, 1908, indicates that only the former is valid and that the latter is a junior subjective synonym of the extant C. siamensisSchneider, 1801. Gavialis bengawanicus is diagnosed by a relatively small number of maxillary and dentary teeth, a modest maxillary process developed into the lacrimal, a

Massimo Delfino; John De Vos

2010-01-01

80

The evolution and development of cranial form in Homo sapiens  

PubMed Central

Despite much data, there is no unanimity over how to define Homo sapiens in the fossil record. Here, we examine cranial variation among Pleistocene and recent human fossils by using a model of cranial growth to identify unique derived features (autapomorphies) that reliably distinguish fossils attributed to “anatomically modern” H. sapiens (AMHS) from those attributed to various taxa of “archaic” Homo spp. (AH) and to test hypotheses about the changes in cranial development that underlie the origin of modern human cranial form. In terms of pattern, AMHS crania are uniquely characterized by two general structural autapomorphies: facial retraction and neurocranial globularity. Morphometric analysis of the ontogeny of these autapomorphies indicates that the developmental changes that led to modern human cranial form derive from a combination of shifts in cranial base angle, cranial fossae length and width, and facial length. These morphological changes, some of which may have occurred because of relative size increases in the temporal and possibly the frontal lobes, occur early in ontogeny, and their effects on facial retraction and neurocranial globularity discriminate AMHS from AH crania. The existence of these autapomorphies supports the hypothesis that AMHS is a distinct species from taxa of “archaic” Homo (e.g., Homo neanderthalensis).

Lieberman, Daniel E.; McBratney, Brandeis M.; Krovitz, Gail

2002-01-01

81

The evolutionary history of the hominin hand since the last common ancestor of Pan and Homo  

Microsoft Academic Search

Molecular evidence indicates that the last common ancestor of the genus Pan and the hominin clade existed between 8 and 4 million years ago (Ma). The current fossil record indicates the Pan-Homo last common ancestor existed at least 5 Ma and most likely between 6 and 7 Ma. Together, the molecular and fossil evidence has important consequences for interpreting the

Matthew W. Tocheri; Caley M. Orr; Marc C. Jacofsky; Mary W. Marzke

2008-01-01

82

A multi-disciplinary seriation of early Homo and Paranthropus bearing palaeocaves in southern Africa  

Microsoft Academic Search

Fossils of early Homo and Paranthropus have been recovered from several sites in southern Africa. Unfortunately, their precise age has historically been difficult to assess, hampering the reconstruction of their relationships to each other and to fossils from eastern Africa. Multi-dating strategies combining biochronological, archaeological, palaeomagnetic, electron spin resonance (ESR) and uranium series techniques are now clarifying their age. The

Andy I. R. Herries; Darren Curnoe; Justin W. Adams

2009-01-01

83

Human evolution. Evolution of early Homo: an integrated biological perspective.  

PubMed

Integration of evidence over the past decade has revised understandings about the major adaptations underlying the origin and early evolution of the genus Homo. Many features associated with Homo sapiens, including our large linear bodies, elongated hind limbs, large energy-expensive brains, reduced sexual dimorphism, increased carnivory, and unique life history traits, were once thought to have evolved near the origin of the genus in response to heightened aridity and open habitats in Africa. However, recent analyses of fossil, archaeological, and environmental data indicate that such traits did not arise as a single package. Instead, some arose substantially earlier and some later than previously thought. From ~2.5 to 1.5 million years ago, three lineages of early Homo evolved in a context of habitat instability and fragmentation on seasonal, intergenerational, and evolutionary time scales. These contexts gave a selective advantage to traits, such as dietary flexibility and larger body size, that facilitated survival in shifting environments. PMID:24994657

Antón, Susan C; Potts, Richard; Aiello, Leslie C

2014-07-01

84

The distinctiveness and systematic context of Homo neanderthalensis  

Microsoft Academic Search

The “packaging” of the diverse living world is untidy, with the result that there are no absolute criteria for recognizing\\u000a in all contexts the bounded historical entities we call species. However, there is no doubt whatsoever that Homo neanderthalensis is as clear-cut a morphological entity as any in the hominid fossil record: one that is characterized by a whole host

I. Tattersall; J. Schwartz

85

The Emergence of Homo sapiens.  

ERIC Educational Resources Information Center

Describes chronologically the evolution of the human race on earth so as to refute Darwin's theory of descent from animals. Skull fragments from sites around the world suggest at least two possible routes toward the emergence of Homo sapiens sapiens. (Author/SK)

Rensberger, Boyce

1980-01-01

86

"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

87

Fossil fuels  

Microsoft Academic Search

The recovery, handling and combustion of fossil fuels is damaging the environment. This damage may ultimately cause many plant and animal species to become extinct. If we continue to increase our use of fossil fuels for energy production, humanity may ultimately become one of the species that perish. This is an overwhelming reason to stop the use of fossil fuels

Herman Daly

1994-01-01

88

Homo habilis —A Premature Discovery: Remembered by One of Its Founding Fathers, 42 Years Later  

Microsoft Academic Search

One of the most dramatic contributions to human evolutionary studies made by the Leakey family was their discovery from 1959\\u000a onwards of the hominin fossils to which Louis Leakey, Phillip Tobias and John Napier in 1964 gave the name Homo habilis. The fi rst specimens were found in the lower part of Bed I of the superlative Olduvai Gorge sequence

Phillip V. Tobias

89

The Primitive Wrist of Homo floresiensis and Its Implications for Hominin Evolution  

Microsoft Academic Search

Whether the Late Pleistocene hominin fossils from Flores, Indonesia, represent a new species, Homo floresiensis, or pathological modern humans has been debated. Analysis of three wrist bones from the holotype specimen (LB1) shows that it retains wrist morphology that is primitive for the African ape-human clade. In contrast, Neandertals and modern humans share derived wrist morphology that forms during embryogenesis,

Matthew W. Tocheri; Caley M. Orr; Susan G. Larson; Thomas Sutikna; Jatmiko; E. Wahyu Saptomo; Rokus Awe Due; Tony Djubiantono; Michael J. Morwood; William L. Jungers

2007-01-01

90

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

91

Fossil Excavation  

NSDL National Science Digital Library

In this activity students excavate their own fossil from a teacher-prepared "rock biscuit". Students chip away the matrix with wooden stirring rods (or sharpened wooden dowels) and glue brushes. In each biscuit is a genuine fossil such as a shark's tooth. The activity is designed to be the culmination of a lesson about fossil collecting, the importance of recording data, and different preparation methods.

92

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

93

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

94

Fossil Horses  

Microsoft Academic Search

The family Equidae have an extensive fossil record spanning the past 58 million years, and the evolution of the horse has frequently been used as a classic example of long-term evolution. In recent years, however, there have been many important discoveries of fossil horses, and these, in conjunction with such new methods as cladistics, and techniques such as precise geochronology,

Bruce J. MacFadden

1994-01-01

95

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

96

Maternal and direct effects of elevated CO 2 on seed provisioning, germination and seedling growth in Bromus erectus  

Microsoft Academic Search

Elevated CO2 can affect plant fitness not only through its effects on seed production but also by altering the quality of seeds and therefore\\u000a germination and seedling performance. We collected seeds from mother plants of Bromus erectus grown in field plots at ambient and elevated CO2 (m-CO2, maternal CO2) and germinated them in the greenhouse in a reciprocal design under

Thomas Steinger; Rolf Gall; Bernhard Schmid

2000-01-01

97

Fossil Hunt  

NSDL National Science Digital Library

This activity is structured to allow students to experience one of the largest puzzles in science, the fossil record. Students will be encouraged to ask questions about the nature of science as they experience a simulated fossil hunt. They will be asked to reconstruct a book that has been literally destroyed, just as the fossil record has been changed by billions of years of geological processes. They will gain insight into the academic processes of piecing together bits and pieces of information. This site includes background information, a list of materials, introduction and description of the activity, and suggestions for evaluation.

98

The human genus.  

PubMed

A general problem in biology is how to incorporate information about evolutionary history and adaptation into taxonomy. The problem is exemplified in attempts to define our own genus, Homo. Here conventional criteria for allocating fossil species to Homo are reviewed and are found to be either inappropriate or inoperable. We present a revised definition, based on verifiable criteria, for Homo and conclude that two species, Homo habilis and Homo rudolfensis, do not belong in the genus. The earliest taxon to satisfy the criteria is Homo ergaster, or early African Homo erectus, which currently appears in the fossil record at about 1.9 million years ago. PMID:10102822

Wood, B; Collard, M

1999-04-01

99

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.

100

Homoplasy and early Homo : an analysis of the evolutionary relationships of H. habilis sensu stricto and H. rudolfensis  

Microsoft Academic Search

Dividing the fossils usually assigned to the taxonHomo habilis sensu latointo two species (as most researchers now accept) necessitates a re-examination of their evolutionary relationships. A cladistic analysis of 48 of the most commonly-used cranial characters from recent studies of Pliocene hominid phylogeny and which distinguish two taxa withinH. habilis sensu latosuggests that these fossils have different evolutionary affinities. One

Daniel E. Lieberman; Bernard A. Wood; David R. Pilbeam

1996-01-01

101

On the origin of modern humans in China  

Microsoft Academic Search

The Multiregional Evolution Hypothesis (MEH) and the Recent Out of Africa Hypothesis (ROAH) are two main hypotheses bearing on the origin of modern humans. In China, there are many common morphological features among Pleistocene human fossil skulls. These features and the morphological mosaic between Homo sapiens erectus and Homo sapiens sapiens of China indicate the continuity of human evolution in

Xinzhi Wu

2004-01-01

102

Fossil Horses  

NASA Astrophysics Data System (ADS)

The family Equidae have an extensive fossil record spanning the past 58 million years, and the evolution of the horse has frequently been used as a classic example of long-term evolution. In recent years, however, there have been many important discoveries of fossil horses, and these, in conjunction with such new methods as cladistics, and techniques such as precise geochronology, have allowed us to achieve a much greater understanding of the evolution and biology of this important group. This book synthesizes the large body of data and research relevant to an understanding of fossil horses from several disciplines including biology, geology and paleontology. Using horses as the central theme, the author weaves together in the text such topics as modern geochronology, paleobiogeography, climate change, evolution and extinction, functional morphology, and population biology during the Cenozoic period. This book will be exciting reading for researchers and graduate students in vertebrate paleontology, evolution, and zoology.

MacFadden, Bruce J.

1994-06-01

103

Inventing Homo gardarensis: prestige, pressure, and human evolution in interwar Scandinavia.  

PubMed

In the 1920s there were still very few fossil human remains to support an evolutionary explanation of human origins. Nonetheless, evolution as an explanatory framework was widely accepted. This led to a search for ancestors in several continents with fierce international competition. With so little fossil evidence available and the idea of a Missing Link as a crucial piece of evidence in human evolution still intact, many actors participated in the scientific race to identify the human ancestor. The curious case of Homo gardarensis serves as an example of how personal ambitions and national pride were deeply interconnected as scientific concerns were sometimes slighted in interwar palaeoanthropology. PMID:24941795

Kjaergaard, Peter C

2014-06-01

104

Fossil Algæ  

Microsoft Academic Search

IN a review of Saporta's work on ``Fossil Algæ'' in NATURE (vol. xxvii. p. 514) there are certain opinions brought forward which ought not to be passed by without some remarks. At first it should be stated that Saporta, while still insisting upon the vegetable nature of his so-called ``algæ,'' does not only defend his views about those doubtful bodies

A. G. Nathorst

1883-01-01

105

The evolutionary history of the hominin hand since the last common ancestor of Pan and Homo  

PubMed Central

Molecular evidence indicates that the last common ancestor of the genus Pan and the hominin clade existed between 8 and 4 million years ago (Ma). The current fossil record indicates the Pan-Homo last common ancestor existed at least 5 Ma and most likely between 6 and 7 Ma. Together, the molecular and fossil evidence has important consequences for interpreting the evolutionary history of the hand within the tribe Hominini (hominins). Firstly, parsimony supports the hypothesis that the hand of the last common ancestor most likely resembled that of an extant great ape overall (Pan, Gorilla, and Pongo), and that of an African ape in particular. Second, it provides a context for interpreting the derived changes to the hand that have evolved in various hominins. For example, the Australopithecus afarensis hand is likely derived in comparison with that of the Pan–Homo last common ancestor in having shorter fingers relative to thumb length and more proximo-distally oriented joints between its capitate, second metacarpal, and trapezium. This evidence suggests that these derived features evolved prior to the intensification of stone tool-related hominin behaviors beginning around 2.5 Ma. However, a majority of primitive features most likely present in the Pan-Homo last common ancestor are retained in the hands of Australopithecus, Paranthropus/early Homo, and Homo floresiensis. This evidence suggests that further derived changes to the hands of other hominins such as modern humans and Neandertals did not evolve until after 2.5 Ma and possibly even later than 1.5 Ma, which is currently the earliest evidence of Acheulian technology. The derived hands of modern humans and Neandertals may indicate a morphological commitment to tool-related manipulative behaviors beyond that observed in other hominins, including those (e.g. H. floresiensis) which may be descended from earlier tool-making species.

Tocheri, Matthew W; Orr, Caley M; Jacofsky, Marc C; Marzke, Mary W

2008-01-01

106

Quaternary fossil fish from the Kibish Formation, Omo Valley, Ethiopia  

Microsoft Academic Search

The late Quaternary Kibish Formation of the Omo Valley, southwestern Ethiopia, preserves environments reflecting a history of fluctuations in the level of nearby Lake Turkana over the past 200,000 years. The Kibish Formation has yielded a diverse mammalian fauna (as well as birds and crocodiles), stone tools, and the oldest anatomically modern Homo sapiens. Fish, the most common vertebrate fossils

Josh Trapani

2008-01-01

107

Anatomical study: comparison of the cranial fragment from venta micena, (orce; Spain) with fossil and extant mammals  

Microsoft Academic Search

The fragment of the skull of Orce attributed to the genusHomo is compared with fossil and extant mammals. The anatomical analysis supports the idea of ascribing it to an infantile individual\\u000a of the genusHomo, close to the primitive Turkana specimens.

J. Gibert; F. Ribot; C. Ferrandez; B. Martinez; R. Caporicci; D. Campillo

1989-01-01

108

Technical note: virtual reconstruction of KNM-ER 1813 Homo habilis cranium.  

PubMed

A very limiting factor for paleoanthropological studies is the poor state of preservation of the human fossil record, where fragmentation and deformation are considered normal. Although anatomical information can still be gathered from a distorted fossil, such specimens must typically be excluded from advanced morphological and morphometric analyses, thus reducing the fossil sample size and, ultimately, our knowledge of human evolution. In this contribution we provide the first digital reconstruction of the KNM-ER 1813 Homo habilis cranium. Based on state of-the-art three-dimensional digital modeling and geometric morphometric (GM) methods, the facial portion was aligned to the neurocranium, the overall distortion was removed, and the missing regions were restored. The reconstructed KNM-ER 1813 allows for an adjustment of the anthropometric measurements gathered on the original fossil. It is suitable for further quantitative studies, such as GM analyses focused on skull morphology or for finite element analysis to explore the mechanics of early Homo feeding behavior and diet. PMID:24318950

Benazzi, Stefano; Gruppioni, Giorgio; Strait, David S; Hublin, Jean-Jacques

2014-01-01

109

Radiometric dating of the type-site for Homo heidelbergensis at Mauer, Germany  

PubMed Central

The Mauer mandible, holotype of Homo heidelbergensis, was found in 1907 in fluvial sands deposited by the Neckar River 10 km southeast of Heidelberg, Germany. The fossil is an important key to understanding early human occupation of Europe north of the Alps. Given the associated mammal fauna and the geological context, the find layer has been placed in the early Middle Pleistocene, but confirmatory chronometric evidence has hitherto been missing. Here we show that two independent techniques, the combined electron spin resonance/U-series method used with mammal teeth and infrared radiofluorescence applied to sand grains, date the type-site of Homo heidelbergensis at Mauer to 609 ± 40 ka. This result demonstrates that the mandible is the oldest hominin fossil reported to date from central and northern Europe and raises questions concerning the phyletic relationship of Homo heidelbergensis to more ancient populations documented from southern Europe and in Africa. We address the paleoanthropological significance of the Mauer jaw in light of this dating evidence.

Wagner, Gunther A.; Krbetschek, Matthias; Degering, Detlev; Bahain, Jean-Jacques; Shao, Qingfeng; Falgueres, Christophe; Voinchet, Pierre; Dolo, Jean-Michel; Garcia, Tristan; Rightmire, G. Philip

2010-01-01

110

Mandible and Taxonomy of the Earliest European Homo  

Microsoft Academic Search

Although variability of the mandible makes it problematic for taxonomy, the holotypes of three of the oldest European species,\\u000a Home georgicus, H. antecessor, H. heidelbergensis, are mandibles. Moreover, the distinctive validity of these three species cannot be established from these particular mandibles.\\u000a The holotype of H. georgicus is pathological and similar to H. erectus in some important features, while others

P. F. Fabbri

2006-01-01

111

Genetics and the making of Homo sapiens  

Microsoft Academic Search

Understanding the genetic basis of the physical and behavioural traits that distinguish humans from other primates presents one of the great new challenges in biology. Of the millions of base-pair differences between humans and chimpanzees, which particular changes contributed to the evolution of human features after the separation of the Pan and Homo lineages 5–7 million years ago? How can

Sean B. Carroll

2003-01-01

112

The Hedonistic Paradox: Is homo economicus happier?  

Microsoft Academic Search

The “Hedonistic Paradox” states that homo economicus, or someone who seeks happiness for him- or herself, will not find it, but the person who helps others will. This study examines two questions in connection with happiness and generosity. First, do more generous people, as identified in dictator experiments, report on average greater happiness, or subjective well-being (SWB), as measured by

James Konow; Joseph Earley

2008-01-01

113

Yawn Contagion and Empathy in Homo sapiens  

Microsoft Academic Search

The ability to share others' emotions, or empathy, is crucial for complex social interactions. Clinical, psychological, and neurobiological clues suggest a link between yawn contagion and empathy in humans (Homo sapiens). However, no behavioral evidence has been provided so far. We tested the effect of different variables (e.g., country of origin, sex, yawn characteristics) on yawn contagion by running mixed

Ivan Norscia; Elisabetta Palagi

2011-01-01

114

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

115

Melanocortin receptors form constitutive homo- and heterodimers  

Microsoft Academic Search

A significant number of G protein-coupled receptors are shown to form homo- or heterodimers\\/oligomers, and oligomerization of GPCRs may be a quite general phenomenon. We have here explored the possibility that the two closely related human melanocortin receptor 1 (MC1R) and melanocortin receptor 3 (MC3R) form dimers. Using bioluminescence resonance energy transfer (BRET2) we demonstrate that MC1 and MC3Rs form

Ilona Mandrika; Ramona Petrovska; Jarl Wikberg

2005-01-01

116

Comparisons of Early Pleistocene Skulls from East Africa and the Georgian Caucasus: Evidence Bearing on the Origin and Systematics of Genus Homo  

Microsoft Academic Search

A half century ago, when there were fewer fossils (and not so many paleoanthropologists), characterizing the genus Homo was relatively straightforward. In addition to modern humans, Neanderthals could be included, along with other archaics such\\u000a as Broken Hill (now Kabwe) from Zambia and the Ngandong assemblage from Java. Also, it was becoming clear that Atlanthropus from northern Africa, and Pithecanthropus

G. Philip Rightmire; David Lordkipanidze

117

Dental microwear texture analysis and diet in the Dmanisi hominins.  

PubMed

Reconstructions of foraging behavior and diet are central to our understanding of fossil hominin ecology and evolution. Current hypotheses for the evolution of the genus Homo invoke a change in foraging behavior to include higher quality foods. Recent microwear texture analyses of fossil hominin teeth have suggested that the evolution of Homo erectus may have been marked by a transition to a more variable diet. In this study, we used microwear texture analysis to examine the occlusal surface of 2 molars from Dmanisi, a 1.8 million year old fossil hominin site in the Republic of Georgia. The Dmanisi molars were characterized by a moderate degree of surface complexity (Asfc), low textural fill volume (Tfv), and a relatively low scale of maximum complexity (Smc), similar to specimens of early African H. erectus. While caution must be used in drawing conclusions from this small sample (n = 2), these results are consistent with continuity in diet as H. erectus expanded into Eurasia. PMID:22030152

Pontzer, Herman; Scott, Jessica R; Lordkipanidze, David; Ungar, Peter S

2011-12-01

118

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.

119

Fossil Hominids: The Evidence for Human Evolution  

NSDL National Science Digital Library

This Web site from Talk.Origins, a "Usenet newsgroup devoted to the discussion and debate of biological and physical origins," aims to "provide an overview of the study of human evolution, and of the currently accepted fossil evidence." Recognized for excellence by a number of science and education organizations, this site has been updated to include new material concerning Homo habilus and two newly discovered fossil hominid skulls. As before, the site also offers an overview of the latest developments in paleoanthropology, general information about hominid species, and links and references, as well as closely following the controversial evolution vs. creationism debate. The site is simply presented and easy to navigate, and offers a convenient way to keep current with paleoanthropological issues.

1996-01-01

120

Encephalization and allometric trajectories in the genus Homo: Evidence from the Neandertal and modern lineages  

PubMed Central

The term “encephalization” is commonly used to describe an enlargement in brain size, considered as either absolute endocranial volumes or relative values in relation to body size. It is widely recognized that a considerable endocranial expansion occurred throughout the evolution of the genus Homo. This article aims to evaluate whether this phenomenon was the outcome of distinct evolutionary lineages, reaching similar brain expansions but through different trajectories. Endocranial morphology was studied in a sample of fossil hominines by multivariate approaches using both traditional metrics and geometric morphometrics. The analysis was focused on the transition from a generalized archaic pattern within the genus Homo to the modern morphology and compared with changes that occurred along the Neandertal lineage. The main result was the identification of two different evolutionary trajectories, in which a similar expansion in endocranial size has been reached by different changes in shape. Along the Neandertal lineage we observed maintenance of an “archaic” endocranial model, in which a large amount of variability is based on a single allometric trend. By contrast, when modern endocasts were compared with nonmodern ones, we found important differences apparently led by a parietal expansion. In this light, the origin of our species may have represented the opportunity to surpass the constraints imposed on encephalization by the ontogenetic pattern shared by nonmodern Homo representatives.

Bruner, Emiliano; Manzi, Giorgio; Arsuaga, Juan Luis

2003-01-01

121

Human evolution.  

PubMed

The common ancestor of modern humans and the great apes is estimated to have lived between 5 and 8 Myrs ago, but the earliest evidence in the human, or hominid, fossil record is Ardipithecus ramidus, from a 4.5 Myr Ethiopian site. This genus was succeeded by Australopithecus, within which four species are presently recognised. All combine a relatively primitive postcranial skeleton, a dentition with expanded chewing teeth and a small brain. The most primitive species in our own genus, Homo habilis and Homo rudolfensis, are little advanced over the australopithecines and with hindsight their inclusion in Homo may not be appropriate. The first species to share a substantial number of features with later Homo is Homo ergaster, or 'early African Homo erectus', which appears in the fossil record around 2.0 Myr. Outside Africa, fossil hominids appear as Homo erectus-like hominids, in mainland Asia and in Indonesia close to 2 Myr ago; the earliest good evidence of 'archaic Homo' in Europe is dated at between 600-700 Kyr before the present. Anatomically modern human, or Homo sapiens, fossils are seen first in the fossil record in Africa around 150 Kyr ago. Taken together with molecular evidence on the extent of DNA variation, this suggests that the transition from 'archaic' to 'modern' Homo may have taken place in Africa. PMID:8976151

Wood, B

1996-12-01

122

Genome Digging: Insight into the Mitochondrial Genome of Homo  

PubMed Central

Background A fraction of the Neanderthal mitochondrial genome sequence has a similarity with a 5,839-bp nuclear DNA sequence of mitochondrial origin (numt) on the human chromosome 1. This fact has never been interpreted. Although this phenomenon may be attributed to contamination and mosaic assembly of Neanderthal mtDNA from short sequencing reads, we explain the mysterious similarity by integration of this numt (mtAncestor-1) into the nuclear genome of the common ancestor of Neanderthals and modern humans not long before their reproductive split. Principal Findings Exploiting bioinformatics, we uncovered an additional numt (mtAncestor-2) with a high similarity to the Neanderthal mtDNA and indicated that both numts represent almost identical replicas of the mtDNA sequences ancestral to the mitochondrial genomes of Neanderthals and modern humans. In the proteins, encoded by mtDNA, the majority of amino acids distinguishing chimpanzees from humans and Neanderthals were acquired by the ancestral hominins. The overall rate of nonsynonymous evolution in Neanderthal mitochondrial protein-coding genes is not higher than in other lineages. The model incorporating the ancestral hominin mtDNA sequences estimates the average divergence age of the mtDNAs of Neanderthals and modern humans to be 450,000–485,000 years. The mtAncestor-1 and mtAncestor-2 sequences were incorporated into the nuclear genome approximately 620,000 years and 2,885,000 years ago, respectively. Conclusions This study provides the first insight into the evolution of the mitochondrial DNA in hominins ancestral to Neanderthals and humans. We hypothesize that mtAncestor-1 and mtAncestor-2 are likely to be molecular fossils of the mtDNAs of Homo heidelbergensis and a stem Homo lineage. The dN/dS dynamics suggests that the effective population size of extinct hominins was low. However, the hominin lineage ancestral to humans, Neanderthals and H. heidelbergensis, had a larger effective population size and possessed genetic diversity comparable with those of chimpanzee and gorilla.

Ovchinnikov, Igor V.; Kholina, Olga I.

2010-01-01

123

Craniofacial variation in Homo habilis: an analysis of the evidence for multiple species.  

PubMed

The question of heterogeneity in the Homo habilis sample continues to be controversial. Various lines of evidence have been used to reject the null hypothesis of intraspecific variation. This evidence derives from analyses of endocranial volume variation, probability estimates of sexual dimorphism, facial variation, cranial angles, CV analysis of craniofacial variation, the multivariate pattern of sexual dimorphism, the pattern of variability (CV) profiles, distance data using exact randomization methods, and various kinds of quantitative ordinations of fossils. Although consensus is lacking as to how the H. habilis sample is to be split, there is a growing perception that the degree of variation among the fossils is too great and the pattern of variation is too different to be explained by intraspecific variation. This has resulted in the recognition of new species such as "Homo rudolfensis." The present study critically examines the evidence commonly cited as the basis for recognizing multiple species in the extended H. habilis hypodigm. Reanalysis and reinterpretation of these data indicates that: (1) the degree of variation in the H. habilis sample is typical of modern hominoids, and (2) the pattern of variation among specimens of the H. habilis sample is consistent with intraspecific variation. Thus, at present, there is no sound basis to reject the null hypothesis of intraspecific variation as an adequate explanation of the morphological variation seen among specimens of the extended H. habilis sample. If multiple species are indeed represented, then their presence has not yet been satisfactorily demonstrated. PMID:10766947

Miller, J M

2000-05-01

124

The hominin fossil record: taxa, grades and clades  

PubMed Central

This paper begins by reviewing the fossil evidence for human evolution. It presents summaries of each of the taxa recognized in a relatively speciose hominin taxonomy. These taxa are grouped in grades, namely possible and probable hominins, archaic hominins, megadont archaic hominins, transitional hominins, pre-modern Homo and anatomically modern Homo. The second part of this contribution considers some of the controversies that surround hominin taxonomy and systematics. The first is the vexed question of how you tell an early hominin from an early panin, or from taxa belonging to an extinct clade closely related to the Pan-Homo clade. Secondly, we consider how many species should be recognized within the hominin fossil record, and review the philosophies and methods used to identify taxa within the hominin fossil record. Thirdly, we examine how relationships within the hominin clade are investigated, including descriptions of the methods used to break down an integrated structure into tractable analytical units, and then how cladograms are generated and compared. We then review the internal structure of the hominin clade, including the problem of how many subclades should be recognized within the hominin clade, and we examine the reliability of hominin cladistic hypotheses. The last part of the paper reviews the concepts of a genus, including the criteria that should be used for recognizing genera within the hominin clade.

Wood, Bernard; Lonergan, Nicholas

2008-01-01

125

New Middle Pleistocene hominid crania from Yunxian in China  

Microsoft Academic Search

TWO fossil human crania have been found in Middle Pleistocene terrace deposits of the Han River in Yun county (Yunxian), Hubei province, China (Figs 1 and 2)1. These damaged but relatively complete adult specimens show a mixture of features associated both with Homo erectus and with 'archaic H. sapiens'. The Yunxian crania (Figs 3 and 4), although crushed and distorted

Li Tianyuan; Dennis A. Etler

1992-01-01

126

Make a Fossil!  

NSDL National Science Digital Library

In this activity, make your own fossils using a shell, preferably with an interesting texture and strong edges. Use Plaster of Paris to create a mold fossil. This activity guide includes a step-by-step instructional video.

Center, Saint L.

2013-01-17

127

Overcoming Fossilized English.  

ERIC Educational Resources Information Center

Causes of language fossilization and ways to overcome it are considered. Fossilization is the relatively permanent incorporation of incorrect linguistic forms into a person's second language competence. The discussion is focused on fossilization of incorrect syntactical rules, based on experiences with learners of English as a second language at…

Graham, Janet G.

128

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.

129

Hominid Fossils from Dmanisi and Their Place Among the Early Hominids  

Microsoft Academic Search

Discoveries of Homo remains consisting of four craniums and four mandibles with several post- cranial remains, stone artifacts of Olduvai type Mode 1 (13) and faunal fossils that points to a latest Pliocene - earliest Pleistocene age during the excavations in Dmanisi, Republic of Georgia, yielding the age of 1.81 M. yr. (Ar40\\/Ar39) have reopened the debate about the first

David Lordkipanidze; Abesalom Vekua; Philip G. Rightmire; Ann Margvelashvili

130

Out of Africa and back again  

Microsoft Academic Search

If the genusHomo did indeed originate in Africa, then it must have spread by about 2 m.y. ago into Asia where it is represented at 1.8 m.y.\\u000a ago byHomo erectus fossils. This latter species in turn eventually spread back into Africa, as indicated by the 1.4 m.y. old OH 9 calvaria from\\u000a Olduvai, and into Europe, as indicated by the

R. J. Clarke; J. W. Goethe Universittit

2000-01-01

131

Homo- and heterometallic planes, chains and cubanes.  

PubMed

The synthesis, structural and magnetic characterisation of a family of homo- and heterometallic complexes constructed with the Schiff base ligands 2-iminomethyl-6-methoxy-phenol (L1H) and 2-imino-6-methoxy-phenol (L2H), are discussed. Members include the heterometallic tetranuclear complexes of general formula [Na2M2(X)2(L1)4(Y)2] (where M = Fe(III), X = (-)OMe, Y = NO3(-) (1) and M = Ni(II), X = N3(-) and Y = MeCN (2)), each possessing a butterfly-like topology. We also report the formation of the heterometallic molecular cage [Na3Ni2(L1)6](ClO4) (3) whose metallic skeleton describes a [rare] trigonal bipyramid, the homometallic 1-D coordination polymer [Mn(L1)2(Cl)]n (4), and the tetranuclear cubane clusters [Mn(III)3Mn(IV)(O)3(OEt)(OAc)3(L1)3] (5) and [Ni4(?3-OMe)4(L2)4(MeOH)4] (6). Dc and ac magnetic susceptibility studies on complexes 5 and 6 reveal S = 9/2 and S = 4 spin ground states. PMID:23739726

Meally, Seán T; Taylor, Stephanie M; Brechin, Euan K; Piligkos, Stergios; Jones, Leigh F

2013-07-28

132

Brief communication: two human fossil deciduous molars from the Sangiran dome (Java, Indonesia): outer and inner morphology.  

PubMed

Currently, the human deciduous dental record from the Pleistocene deposits of the Sangiran Dome, Java, consists of only eight specimens. Here we report two deciduous crowns collected near the village of Pucung. While their precise geo-chronological context remains unknown, a provenance from the Early-Middle Pleistocene Kabuh Formation, or from the Early Pleistocene "Grenzbank Zone," is very likely. These isolated specimens consist of an upper first molar (PCG.1) and a lower second molar (PCG.2). Taxonomic discrimination of the Indonesian tooth record is difficult because of the convergence in crown size and appearance between Pongo and Homo. Accordingly, as PCG.2 still bears a concretion masking most of its features, we coupled the outer analysis of the two specimens with an investigation of their inner morphology. In addition to external characteristics, virtual imaging and quantitative assessment of inner morphology and tissue proportions support an attribution to the taxon Homo, and we preliminary allocate both specimens toH. erectus. PMID:22281866

Zanolli, Clément; Bondioli, Luca; Mancini, Lucia; Mazurier, Arnaud; Widianto, Harry; Macchiarelli, Roberto

2012-03-01

133

A re-examination of the human fossil specimen from Ba?ki Petrovac (Serbia).  

PubMed

A fragmented human calotte was discovered during the early 1950s near Ba?ki Petrovac (Serbia), in association with Palaeolithic stone tools. After its initial publication, the fossil specimen remained largely unknown outside of the Serbian academe and no detailed comparative study has ever been carried out. Since the whereabouts of the fossil itself are currently unknown, and given its potential significance for the Pleistocene human evolution, we re-examine the data published by Živanovi? (1966, 1975). Using the original measurements, mostly taken on the frontal bone, and a wide comparative sample of 68 fossil specimens, the fossil was compared and analyzed by statistical multivariate methods. We also conducted a visual examination of the morphology based on the available photographic material. Our analysis reveals phenetic similarity with Middle Pleistocene archaic Homo from Africa and anatomically modern Homo sapiens. However, the absence of primitive cranial traits in Ba?ki Petrovac indicates a clear modern Homo sapiens designation. Although lost at the moment, there is a chance for the re-discovery of the fossil in the years to come. This would give us an opportunity to acquire absolute dates and to study the specimen in a more detailed manner. PMID:24951407

Radovi?, Predrag; Lindal, Joshua Allan; Roksandic, Mirjana

2014-08-01

134

Mandibular molar root morphology in Neanderthals and Late Pleistocene and recent Homo sapiens.  

PubMed

Neanderthals have a distinctive suite of dental features, including large anterior crown and root dimensions and molars with enlarged pulp cavities. Yet, there is little known about variation in molar root morphology in Neanderthals and other recent and fossil members of Homo. Here, we provide the first comprehensive metric analysis of permanent mandibular molar root morphology in Middle and Late Pleistocene Homo neanderthalensis, and Late Pleistocene (Aterian) and recent Homo sapiens. We specifically address the question of whether root form can be used to distinguish between these groups and assess whether any variation in root form can be related to differences in tooth function. We apply a microtomographic imaging approach to visualise and quantify the external and internal dental morphologies of both isolated molars and molars embedded in the mandible (n=127). Univariate and multivariate analyses reveal both similarities (root length and pulp volume) and differences (occurrence of pyramidal roots and dental tissue volume proportion) in molar root morphology among penecontemporaneous Neanderthals and Aterian H. sapiens. In contrast, the molars of recent H. sapiens are markedly smaller than both Pleistocene H. sapiens and Neanderthals, but share with the former the dentine volume reduction and a smaller root-to-crown volume compared with Neanderthals. Furthermore, we found the first molar to have the largest average root surface area in recent H. sapiens and Neanderthals, although in the latter the difference between M(1) and M(2) is small. In contrast, Aterian H. sapiens root surface areas peak at M(2). Since root surface area is linked to masticatory function, this suggests a distinct occlusal loading regime in Neanderthals compared with both recent and Pleistocene H. sapiens. PMID:20719359

Kupczik, Kornelius; Hublin, Jean-Jacques

2010-11-01

135

Morphometric comparisons between crania of Late Pleistocene Homo sapiens from Border Cave (BC 1), Tuinplaas (TP 1) and modern southern African populations  

Microsoft Academic Search

Two Late Pleistocene fossil specimens, Border Cave hominin 1 (BC 1) and Tuinplaas hominin 1 (TP 1), are thought to be among the earliest known “anatomically modern” Homo sapiens in southern Africa. Cranial measurements of these two specimens are compared against corresponding data from modern KhoeSan and non-KhoeSan crania, representing respectively “Bushman” and Bantu-speaking populations from southern Africa. Morphometric comparisons

K. Houghton; J. F. Thackeray

2011-01-01

136

Fossil evidence for early hominid tool use.  

PubMed

Although several Plio-Pleistocene hominids are found in association with stone and bone tools, it has been generally assumed that at any one time the hominid with the largest brain was the toolmaker. Fossils recovered over the last decade suggest that early hominids subsequent to 2.5 million years ago all might have used tools and occupied "cultural" niches. A test for humanlike precision grasping (the enhanced ability to manipulate tools) is proposed and applied to australopithecines and early Homo. The results indicate that tools were likely to have been used by all early hominids at around 2.0 million years ago. The earliest australopithecines, which predate the appearance of stone tools in the archaeological record, do not show signs of advanced precision grasping. PMID:8079169

Susman, R L

1994-09-01

137

Narrow-Band Inverted Homo-Heterojunction Avalanche Photodiode.  

National Technical Information Service (NTIS)

The patent application describes a narrow-band, inverted homo-heterojunction avalanche photodiode, configured in the shape of a mesa situated upon a substrate which is transparent to selected light energy wavelengths. The diode is inverted for operation s...

R. C. Eden

1977-01-01

138

AUSTRALOPITHECUS TO HOMO: Transformations in Body and Mind  

Microsoft Academic Search

? Abstract Significant changes,occurred in human,evolution between,2.5 and 1.8 million years ago. Stone tools first appeared, brains expanded, bodies enlarged, sexual dimorphism in body size decreased, limb proportions changed, cheek teeth reduced in size, and crania began to share more unique features with later Homo. Although the two earliest species of Homo, H. habilis and H. rudolfensis, retained many prim-

Henry M. McHenry; Katherine Coffing

2000-01-01

139

Homo-and heterometal complexes with sterically eclipsed ortho -nitrosophenol  

Microsoft Academic Search

Novel homo-and heterometal complexes based on 4,6-di-tert-butyl-2-nitrosophenol (HL) were synthesized, and their physicochemical properties were studied. The data of the 1H NMR, electronic spectroscopy, magnetochemical measurements, and the atomic absorption study suggest that the nitroso group\\u000a of a ligand can be bidentate in polynuclear coordination compounds. The experimental data were obtained for the first time\\u000a on self-assembling of both homo-and

A. M. Ionov; S. N. Lyubchenko; V. A. Kogan; A. Yu. Tsivadze

2008-01-01

140

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

141

"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

142

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

143

Trace Fossil Image Database  

NSDL National Science Digital Library

This database from Emory University consists of images and basic information concerning trace fossils photographed by Anthony Martin. Included in this information is the formation, age, and locality of the specimen if known. Many of the images were originally photographed while in the field, and each type of trace fossil has numerous examples to browse through.

Martin, Anthony; University, Emory

144

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

145

Fossil Dig Site  

NSDL National Science Digital Library

In this activity (located on page 5 of PDF), learners work in groups to create dig sites for display. Learners arrange dry, uncooked pasta "bones" to resemble dinosaur fossils on a foam tray of wet soil. Use this activity to introduce learners to dinosaur anatomy, dig sites, fossils, and paleontology in general.

Museum, Chicago C.

2011-01-01

146

Dinosaur Footprints & Fossils  

NSDL National Science Digital Library

In this activity, early learners simulate fossil prints in play dough or clay. Using plastic dinosaur feet to make footprints on their âmudâ (much as dinosaurs walked around their habitat) and harvest items (leaves, corn, twigs, acorns) to make impressions, learners simulate fossil prints. This resource includes open-ended discussion questions to encourage reflection.

Omsi

2004-01-01

147

Make a Model Fossil  

NSDL National Science Digital Library

This activity is a combination outdoor/indoor lab where students will collect natural materials from the environment and use them to create both a mold and cast model of a fossil. Students will learn how a fossil is formed and why scientists use models to help them understand how things work and develop.

148

Internal nasal floor configuration in Homo with special reference to the evolution of Neandertal facial form.  

PubMed

The presence of a steeply sloping or depressed nasal floor within the nasal cavity of Neandertals is frequently mentioned as a likely specialization or autapomorphy. The depressed nasal floor has also been seen as contributing to a relatively more capacious nasal cavity in Neandertals, which is tied to cold-climate respiratory adaptation and energetics. These observations have been limited largely to a relatively few intact crania, and the character states associated with this trait have not been as precisely codified or analyzed as those published for Plio-Pleistocene hominins (McCollum et al., 1993, J. Hum. Evol. 24, 87; McCollum, 2000, Am. J. Phys. Anthrop. 112, 275). This study examines the internal nasal floor topography in complete crania and isolated maxillae in European, west Asian, and African fossil Homo (n=158) including 25 Neandertals, and a wide range of recent humans from Europe, the Near East, and Africa (n=522). The configuration of the internal nasal floor relative to the nasal cavity entrance is codified as: 1) level, forming a smooth continuous plane; 2) sloped or mildly stepped; or 3) bilevel with a pronounced vertical depression. The frequency of these nasal floor configurations, and their relationship to both nasal margin cresting patterning and a comprehensive set of nasofacial metrics is examined. Neandertals show a high frequency of the bilevel (depressed) configuration in both adults and subadults (80%), but this configuration is also present in lower frequencies in Middle Pleistocene African, Late Pleistocene non-Neandertal (Skhul, Qafzeh), and European Later Upper Paleolithic samples (15%-50%). The bilevel configuration is also present in lower frequencies (ca. 10%) in all recent human samples, but attains nearly 20% in some sub-Saharan African samples. Across extinct and extant Homo (excluding Neandertals), internal nasal floor configuration is not associated with piriform aperture nasal margin patterning, but the two are strongly linked in Neandertals. Variation in internal nasal floor configuration in recent humans is primarily associated with internal nasal fossa breadth and nasal bridge elevation, whereas in fossil hominins, it is associated primarily with variation in facial height. Cold-climate and activity-related thermal adaptation as an explanation for the high frequency of pronounced nasal floor depression in Neandertals is inconsistent with all available data. Alternatively, variation in internal nasal floor configuration is more likely related to stochastically derived populational differences in fetal nasofacial growth patterns that do not sharply differentiate genus Homo taxa (i.e., cladistically), but do phenetically differentiate groups, in particular the Neandertals, especially when considered in combination with other nasofacial features. PMID:12799160

Franciscus, Robert G

2003-06-01

149

Early Pleistocene 40Ar\\/39Ar ages for Bapang Formation hominins, Central Jawa, Indonesia  

Microsoft Academic Search

The Sangiran dome is the primary stratigraphic window for the Plio-Pleistocene deposits of the Solo basin of Central Jawa. The dome has yielded nearly 80 Homo erectus fossils, around 50 of which have known findspots. With a hornblende 40 Ar\\/ 39 Ar plateau age of 1.66 ± 0.04 mega-annum (Ma) reportedly associated with two fossils [Swisher, C.C., III, Curtis, G.

Roy Larick; Russell L. Ciochon; Yahdi Zaim; Suminto Sudijono; Yan Rizal; Fachroel Aziz; Mark Reagan; Matthew Heizler

2001-01-01

150

Genotype-specific responses of Bromus erectus to elevated CO{sub 2} at different levels of biodiversity and endophyte infection - a field experiment  

SciTech Connect

In 1994 we initiated a long-term field experiment in a calcareous grassland to study the effects of elevated CO{sub 2} on individuals, populations, and communities. Clonal replicates of 54 genotypes of the dominant grass Bromus erectus were grown in communities planted at three levels of biodiversity (5-, 12-, 31-species plots) and exposed to ambient and elevated CO{sub 2}. The same genotypes were also individually grown in tubes within the field plots. Some genotypes were infected by the endophytic fungus Epichloee typhina. Elevated CO{sub 2} had no significant effects on plant growth, however, there was large variation among genotypes in all measured characters. A significant CO{sub 2}-by-genotype interaction was found for leaf length in the competition-free tubes. Infection by the endophyte led to the abortion of all inflorescences but increased vegetative growth, especially under competitive conditions.

Steinger, T.; Groppe, K.; Schmid, B. [Univ. of Basel (Switzerland)]|[Univ. of Zurich (Switzerland)

1995-06-01

151

The Sima de los Huesos (Burgos, northern Spain): palaeoenvironment and habitats of Homo heidelbergensis during the Middle Pleistocene  

NASA Astrophysics Data System (ADS)

Interpreting how environmental dynamics respond to global climate change and how this has affected human evolution and dispersal is an on-going topic of debate. During the early Middle Pleistocene (˜0.6-0.4 Ma), as compared to earlier, environmental conditions were relatively more stable, with longer climatic cycles alternating between open and forested landscapes. During this interval, humans spread successfully providing an important number of fossil sites where fossils or tools are reported. The Atapuerca-Sima de los Huesos (Burgos, northern Spain) site (Atapuerca-SH) is one of the earliest localities with hominin evidence in the European Middle Pleistocene, with the most important accumulation of Homo heidelbergensis so far. We have analyzed the abundant faunal record from Sima de los Huesos, which is mainly comprised of carnivores, in order to approach an interpretation of the palaeoenvironmental circumstances where these hominids inhabited within the Sierra. Other sites from Sierra de Atapuerca referred to the same Faunal Unit (FU 6), are roughly contemporaneous, and include important ungulates, which are here analyzed with Atapuerca-SH. Additional information provided by isotopic analysis helps elucidate the ancient ecology of taxa present in Sima de los Huesos allowing for an accurate portrayal of the setting in which humans lived. The timing of the spread of Homo heidelbergensis is dominated by a relative climatic and environmental stability and points to a landscape dominated by savannah-like open woodland.

García, Nuria; Arsuaga, Juan Luis

2011-06-01

152

Fossil Halls: Curator Videos  

NSDL National Science Digital Library

Part of a larger virtual tour of the Museum's famed Fossil Halls, this Web site has links to a library of 22 videos highlighting specific exhibits in the hall. The videos are available in broadband and dial-up versions.

153

Advances in Fossil Energy.  

National Technical Information Service (NTIS)

The Morgantown Technology Center is a US Department of Energy fossil fuel research center. It is reponsible for conducting research and development to extract, convert, and utilize coal, oil, and gas in an environmentally acceptable manner. METC performs ...

1984-01-01

154

Minerals and Fossils  

NSDL National Science Digital Library

This site is dedicated to rock and mineral collecting. It contains information for worldwide mineral and fossil collectors with articles, mineral photos, videos, a search engine and free classified ads.

Mineraltown.com

155

Fossil energy program  

NASA Astrophysics Data System (ADS)

The progress made during the period from July 1 through September 30 for the Oak Ridge National Laboratory research and development projects in support of the increased utilization of coal and other fossil fuels as sources of clean energy is reported. The following topics are discussed: coal conversion development, chemical research and development, materials technology, fossil energy materials program, liquefaction projects, component development, process analysis, environmental control technology, atmospheric fluidized bed combustion, underground coal gasification, coal preparation and waste utilization.

McNeese, L. E.

1981-12-01

156

Fossil Simulation in the Classroom  

ERIC Educational Resources Information Center

Describes classroom science demonstrations and experiments that simulate the process of fossil formation. Lists materials, procedures and suggestions for successful activities. Includes ten student activities (coral fossils, leaf fossils, leaf scars, carbonization, etc.). Describes a fossil game in which students work in pairs. (CS)

Hoehn, Robert G.

1977-01-01

157

Earliest human occupations at Dmanisi (Georgian Caucasus) dated to 1.85-1.78 Ma  

PubMed Central

The early Pleistocene colonization of temperate Eurasia by Homo erectus was not only a significant biogeographic event but also a major evolutionary threshold. Dmanisi's rich collection of hominin fossils, revealing a population that was small-brained with both primitive and derived skeletal traits, has been dated to the earliest Upper Matuyama chron (ca. 1.77 Ma). Here we present archaeological and geologic evidence that push back Dmanisi's first occupations to shortly after 1.85 Ma and document repeated use of the site over the last half of the Olduvai subchron, 1.85–1.78 Ma. These discoveries show that the southern Caucasus was occupied repeatedly before Dmanisi's hominin fossil assemblage accumulated, strengthening the probability that this was part of a core area for the colonization of Eurasia. The secure age for Dmanisi's first occupations reveals that Eurasia was probably occupied before Homo erectus appears in the East African fossil record.

Ferring, Reid; Oms, Oriol; Agusti, Jordi; Berna, Francesco; Nioradze, Medea; Shelia, Teona; Tappen, Martha; Vekua, Abesalom; Zhvania, David; Lordkipanidze, David

2011-01-01

158

Trace Fossil Analysis  

NASA Astrophysics Data System (ADS)

Today, the study of trace fossils—ichnology—is an important subdiscipline of geology at the interface of paleontology and sedimentology, mostly because of the efforts of Adolf Seilacher. His ability to synthesize various aspects of ichnology and produce a hierarchy of marine ichna and sedimentary facies has made ichnology useful worldwide in interpreting paleodiversity, rates of sedimentation, oxygenation of bottom water and sediment pore water, and depositional energy. Seilacher's book Trace Fossil Analysis provides a glimpse into the mind, methodology, and insights of the father of modern ichnology, generated from his course notes as a professor and a guest lecturer. The title sounds misleading—readers looking for up-to-date principles and approaches to trace fossil analysis in marine and continental strata will be disappointed. In his preface, however, Seilacher clearly gives direction for the use of his text: “This is a course book—meaning that it is intended to confer not knowledge, but skill.” Thus, it is not meant as a total compilation of all trace fossils, ichnotaxonomy, ichnological interpretations, applications, or the most relevant and up-to-date references. Rather, it takes the reader on a personal journey, explaining how trace fossils are understood in the context of their three-dimensional (3-D) morphology and sedimentary facies.

Hasiotis, Stephen T.

2009-05-01

159

Oldest Homo and Pliocene biogeography of the Malawi Rift  

Microsoft Academic Search

THE Malawi Rift and Pliocene palaeofaunas, which include a hominid mandible attributed to Homo rudolfensis, provide a biogeographical link between the better known Plio-Pleistocene faunal records of East and Southern Africa. The Malawi Rift is in a latitudinal position suitable for recording any hominid and faunal dispersion towards the Equator that was brought on by increased aridity of the Late

Friedemann Schrenk; Timothy G. Bromage; Christian G. Betzler; Uwe Ring; Yusuf M. Juwayeyi

1993-01-01

160

Culture, Speciation and the Genus Homo in Early Humans  

Microsoft Academic Search

Human behaviour, in addition to morphology, is essential to identify man. The characteristics of cultural behaviour are expressed by planning in tool making and territorial organization and by their meaning in the context of life. Cultural behaviour enriched the adaptive strategies of the human species and took on significance in the definition of the genus Homo since H. habilis\\/H. rudolfensis.

Fiorenzo Facchini

2006-01-01

161

A Longitudinal Study of Preschool Children's (Homo sapiens) Sex Segregation  

Microsoft Academic Search

In this 2-year longitudinal study, we hypothesized that sex of the human child (Homo sapiens), differences in physical activity, and time of the year would interact to influence preschool children's sex segregation. We also hypothesized that activity would differentially relate to peer rejection for boys and girls. Consistent with the first hypothesis, high-activity girls started off as the most integrated

Catherine M. Bohn-Gettler; Anthony D. Pellegrini; Danielle Dupuis; Meghan Hickey; Yuefeng Hou; Cary Roseth; David Solberg

2010-01-01

162

New partial skeleton of Homo habilis from Olduvai Gorge, Tanzania  

Microsoft Academic Search

A new partial skeleton of an adult hominid from lower Bed I (about 1.8 Myr ago), Olduvai Gorge, is described. This specimen's craniodental anatomy indicates attribution to Homo habilis, but its postcranial anatomy, including small body size and relatively long arms, is strikingly similar to that of some early Australopithecus individuals.

Donald C. Johanson; Fidelis T. Masao; Gerald G. Eck; Tim D. White; Robert C. Walter; William H. Kimbel; Berhane Asfaw; Paul Manega; Prosper Ndessokia; Gen Suwa

1987-01-01

163

The Fossil Record  

NSDL National Science Digital Library

This lesson plan is part of the DiscoverySchool.com lesson plan library for grades 9-12. It centers around fossils found in the Burgess Shale in western Canada. Topics include body shapes of fossils found, the movement of organisms from oceans to land, and whether organisms existed that did not fossilize. This part of geologic history began in the Cambrian Sea about 540 million years ago. The resource includes objectives, materials, procedures, discussion questions, evaluation ideas, extensions, suggested readings, and vocabulary. There are videos available to order which complement this lesson, an audio-enhanced vocabulary list, and links to teaching tools for making custom quizzes, worksheets, puzzles and lesson plans.

Wu, Lisa

164

What is a Fossil?  

NSDL National Science Digital Library

In this activity about dinosaurs, learners explore how and why fossils form. First, learners are introduced to dinosaur fossils by reading the book "Bones, Bones, Dinosaur Bones" by Byron Barton. Then, learners make impressions in clay using a seashell, pennies, dinosaur teeth and other items. Next, learners make dinosaur tracks in the clay as they "walk" plastic models across the soft clay. Learners also use sponges pre-cut in the shape of dinosaur feet to make more tracks. This activity is featured on page 29 of the "Dinosphere" unit of study for K-2 learners.

Crosslin, Rick; Fortney, Mary; Indianapolis, The C.

2004-01-01

165

FossilPlot  

NSDL National Science Digital Library

This spreadsheet application allows users to make graphs of the diversity and stratigraphic ranges of Phanerozoic marine animals. FossilPlot uses the compendium of marine animal genera compiled by J.J. Sepkoski and his associates at the University of Chicago, from 'A compendium of fossil marine animal genera', found in Bulletins of American Paleontology, v. 363, p. 1-560. The application operates in Microsoft Excel for PC or Mac, and is free for users to download. A slide show on how to use the application (also downloadable) is provided.

166

Fossil Halls: Virtual Tours  

NSDL National Science Digital Library

Part of a larger online look at the Museum's famed Fossil Halls, this Web site has an overview of the halls' many highlights and four QuickTime virtual tours:Hall of Saurischian Dinosaurs, Hall of Ornithischian Dinosaurs, Hall of Primitive Mammals, and Hall of Advanced Mammals.

167

Fossil Halls: Cladistics  

NSDL National Science Digital Library

Part of a larger virtual tour of the Museum's famed Fossil Halls, this Web site has an overview explaining the cladistic method of scientific analysis as well as how to read cladograms. It answers the following questions: What is the best way to reconstruct evolutionary history? What is a cladogram? What is an advanced feature? Why use cladistics?

168

Fossilization of Acidophilic Microorganisms  

Microsoft Academic Search

This study examines fossil microorganisms found in iron-rich deposits in an extreme acidic environment, the Tinto River in SW Spain. Both electron microscopy (SEM and TEM) and non-destructive in situ microanalytical techniques (EDS, EMP and XPS) were used to determine the role of permineralization and encrustation in preserving microorganisms forming biofilms in the sediments. Unicellular algae were preserved by silica

Virginia Souza-Egipsy; Angeles Aguilera; Eva Mateo-Martí; José Angel Martín-Gago; Ricardo Amils

2010-01-01

169

Rethinking Fossil Fuels  

NSDL National Science Digital Library

Climate change and fossil fuel use are connected. It would serve the world well to: begin a moratorium on coal-fired power plants; explore and use renewable energy; insist on immediate action from world governments; and penalize industries putting excess CO2 into the atmosphere.

James Hansen (NASA Goddard Institute for Space Studies;)

2008-09-09

170

Sustainability of Fossil Fuels  

NASA Astrophysics Data System (ADS)

For a sustainable world economy, energy is a bottleneck. Energy is at the basis of a modern, technological society, but unlike materials it cannot be recycled. Energy or more precisely "negentropy" (the opposite of entropy) is always consumed. Thus, one either accepts the use of large but finite resources or must stay within the limits imposed by dilute but self-renewing resources like sunlight. The challenge of sustainable energy is exacerbated by likely growth in world energy demand due to increased population and increased wealth. Most of the world still has to undergo the transition to a wealthy, stable society with the near zero population growth that characterizes a modern industrial society. This represents a huge unmet demand. If ten billion people were to consume energy like North Americans do today, world energy demand would be ten times higher. In addition, technological advances while often improving energy efficiency tend to raise energy demand by offering more opportunity for consumption. Energy consumption still increases at close to the 2.3% per year that would lead to a tenfold increase over the course of the next century. Meeting future energy demands while phasing out fossil fuels appears extremely difficult. Instead, the world needs sustainable or nearly sustainable fossil fuels. I propose the following definition of sustainable under which fossil fuels would well qualify: The use of a technology or resource is sustainable if the intended and unintended consequences will not force its abandonment within a reasonable planning horizon. Of course sustainable technologies must not be limited by resource depletion but this is only one of many concerns. Environmental impacts, excessive land use, and other constraints can equally limit the use of a technology and thus render it unsustainable. In the foreseeable future, fossil fuels are not limited by resource depletion. However, environmental concerns based on climate change and other environmental effects of injecting excess carbon into the environment need to be eliminated before fossil fuels can be considered sustainable. Sustainable fossil fuel use would likely rely on abundant, low-grade hydrocarbons like coal, tar, and shale. It would require a closed cycle approach in which carbon is extracted from the ground, processed for its energy content, and returned into safe and stable sinks for permanent disposal. Such sequestration technologies already exist and more advanced approaches that could maintain access to fossil energy for centuries are on the drawing boards. I will review these options and outline a pathway towards a zero emission fossil fuel based economy that could provide energy at prices comparable to those of today for several centuries. A successful implementation will depend not only on technological advances but also on the development of economic institutions that allow one to pay for the required carbon management. If done correctly the markets will decide whether renewable energy, or sustainable fossil energy provides a better choice.

Lackner, K. S.

2002-05-01

171

Controlled Dimerization of ErbB Receptors Provides Evidence for Differential Signaling by Homo and Heterodimers  

Microsoft Academic Search

The four members of the ErbB family of receptor tyrosine kinases are involved in a complex array of combinatorial interactions involving homo- and heterodimers. Since most cell types express more than one member of the ErbB family, it is difficult to distinguish the biological activities of different homo- and heterodimers. Here we describe a method for inducing homo- or heterodimerization

SENTHIL K. MUTHUSWAMY; MICHAEL GILMAN; JOAN S. BRUGGE

1999-01-01

172

Florissant Fossil Beds National Monument  

NSDL National Science Digital Library

This National Park Service (NPS) website contains details about Florissant Fossil Beds National Monument in Colorado. It includes details about the geological history of the monument, fossils found there, history of the area, flora and fauna, and other details. There is an education page containing curricula for K-12 classes for teaching paleontology. It contains labs, activities, games, vocabulary and fossil identification information.

173

Homo-DNA functionalized carbon nanotube chemical sensors  

Microsoft Academic Search

Arrays of chemical sensors based on homo-oligomer single-stranded DNA (ssDNA) adsorbed to single-walled carbon nanotube field effect transistors (SWNT-FETs) were employed to detect several gaseous analytes. Exposure of these devices to analytes results in a characteristic current shift in the SWNT-FET. The magnitude of this current shift for a particular analyte varies with the base sequence of adsorbed ssDNA and

Samuel M. Khamis; Robert R. Johnson; Zhengtang Luo; A. T. Charlie Johnson

2010-01-01

174

Segregation of type I collagen homo- and heterotrimers in fibrils  

PubMed Central

Normal type I collagen is a heterotrimer of two ?1(I) and one ?2(I) chains, but various genetic and environmental factors result in synthesis of homotrimers which consist of three ?1(I) chains. The homotrimers completely replace the heterotrimers only in rare recessive disorders. In the general population, they may comprise just a small fraction of type I collagen. Nevertheless, they may play a significant role in pathology, e.g., synthesis of 10-15% homotrimers due to a polymorphism in the ?1(I) gene may contribute to osteoporosis. Homotrimer triple helices have different stability and less efficient fibrillogenesis than heterotrimers. Their fibrils have different mechanical properties. However, very little is known about their molecular interactions and fibrillogenesis in mixtures with normal heterotrimers. Here we studied the kinetics and thermodynamics of fibril formation in such mixtures by combining traditional approaches with 3D confocal imaging of fibrils, in which homo- and heterotrimers were labeled by different fluorescent colors. Following a temperature jump from 4 to 32 °C, in a mixture we first observed rapid formation of homotrimer aggregates. The aggregates promoted nucleation of homotrimer fibrils which served as seeds for mixed and heterotrimer fibrils. The separation of colors in confocal images indicated segregation of homo- and heterotrimers at a subfibrillar level throughout the process. The fibril color patterns continued to change slowly after the fibrillogenesis appeared to be complete, due to dissociation and reassociation of the pepsin-treated homo- and heterotrimers, but this remixing did not significantly reduce the segregation even after several days. Independent homo- and heterotrimer solubility measurements in mixtures confirmed that the subfibrillar segregation was an equilibrium property of intermolecular interactions and not just a kinetic phenomenon. We argue that the subfibrillar segregation may exacerbate effects of a small fraction of ?1(I) homotrimers on formation, properties, and remodeling of collagen fibers.

Han, Sejin; McBride, Daniel J.; Losert, Wolfgang; Leikin, Sergey

2010-01-01

175

Homo floresiensis and the evolution of the hominin shoulder  

Microsoft Academic Search

The holotype of Homo floresiensis, diminutive hominins with tiny brains living until 12,000 years ago on the island of Flores, is a partial skeleton (LB1) that includes a partial clavicle (LB1\\/5) and a nearly complete right humerus (LB1\\/50). Although the humerus appears fairly modern in most regards, it is remarkable in displaying only 110° of humeral torsion, well below modern

Susan G. Larson; William L. Jungers; Michael J. Morwood; Thomas Sutikna; Jatmiko; E. Wahyu Saptomo; Rokus Awe Due; Tony Djubiantono

2007-01-01

176

Homo Biometricus: Biometric Recognition Systems and Mobile Internet Services  

Microsoft Academic Search

Biometric procedures are already accepted by millions of people every day on a variety of (social) internet platforms. Biometric identification procedures and their potential applications in everyday life. Currently there is a lot of research in biometrics. In the future also the use of the biometric recognition procedure is going to increase. [DB research]. URL:[http:\\/\\/www.dbresearch.com\\/PROD\\/DBR_INTERNET_EN-PROD\\/PROD0000000000290317\\/Homo+biometricus%3A+Biometric+recognition+systems+and+mobile+internet+services.pdf].

Thomas F Dapp

2012-01-01

177

Fossil Age Estimation Model  

NSDL National Science Digital Library

In this activity (page 1 of the PDF), learners will model how paleontologists estimate the age of fossil discoveries by extracting âfossilâ playing cards from newspapers stacked in chronological order. Learners identify the âageâ of the card based on the âevidenceâ (printed date) in the surrounding pages. They then create a data table and graph and analyze their findings. Use this activity to introduce learners to paleontology and geology. Relates to the linked video, DragonflyTV GPS: Dinosaurs.

Twin Cities Public Television, Inc.

2006-01-01

178

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.

179

Restoring Fossil Creek  

NSDL National Science Digital Library

As part of an ongoing environmental project and partnership with a local university, high school students monitor changes to Fossil Creek in Arizona. Components of the project include fish behavior studies, responses to fishing, water chemistry measurements, aquatic invertebrate studies, photographic recording, riparian habitat transects, and small mammal trapping transects. The data collected will ultimately provide an invaluable annual record for students, working scientists, and the wider community as changes are monitored over time.

Leroy, Carri J.; Marks, Jane C.; Vlieg, Julie; Flaccus, Kathleen

2004-07-01

180

Fossil Microbes on Mars?  

NSDL National Science Digital Library

This online article, from Cosmic Horizons: Astronomy at the Cutting Edge, reports on the controversial discovery of Martian meteorite ALH84001. In 1996, a team of scientists led by David McKay of NASAâs Johnson Space Flight Center announced that they had discovered evidence for microscopic fossil life in this meteorite from Mars. From the start, the evidence was both fascinating and controversial, and to this day it remains so.

181

Homo sapiens, Homo neanderthalensis and the Denisova specimen: New insights on their evolutionary histories using whole-genome comparisons  

PubMed Central

After a brief review of the most recent findings in the study of human evolution, an extensive comparison of the complete genomes of our nearest relative, the chimpanzee (Pan troglodytes), of extant Homo sapiens, archaic Homo neanderthalensis and the Denisova specimen were made. The focus was on non-synonymous mutations, which consequently had an impact on protein levels and these changes were classified according to degree of effect. A total of 10,447 non-synonymous substitutions were found in which the derived allele is fixed or nearly fixed in humans as compared to chimpanzee. Their most frequent location was on chromosome 21. Their presence was then searched in the two archaic genomes. Mutations in 381 genes would imply radical amino acid changes, with a fraction of these related to olfaction and other important physiological processes. Eight new alleles were identified in the Neanderthal and/or Denisova genetic pools. Four others, possibly affecting cognition, occured both in the sapiens and two other archaic genomes. The selective sweep that gave rise to Homo sapiens could, therefore, have initiated before the modern/archaic human divergence.

Paixao-Cortes, Vanessa Rodrigues; Viscardi, Lucas Henrique; Salzano, Francisco Mauro; Hunemeier, Tabita; Bortolini, Maria Catira

2012-01-01

182

Cycles in fossil diversity  

SciTech Connect

It is well-known that the diversity of life appears to fluctuate during the course the Phanerozoic, the eon during which hard shells and skeletons left abundant fossils (0-542 Ma). Using Sepkoski's compendium of the first and last stratigraphic appearances of 36380 marine genera, we report a strong 62 {+-} 3 Myr cycle, which is particularly strong in the shorter-lived genera. The five great extinctions enumerated by Raup and Sepkoski may be an aspect of this cycle. Because of the high statistical significance, we also consider contributing environmental factors and possible causes.

Rohde, Robert A.; Muller, Richard A.

2004-10-20

183

Interpreting Fossil Assemblages  

NSDL National Science Digital Library

Students are provided several fossiliferous samples to analyze in detail. I provide more than they need to snalyze so everyone in the class can be working. I give a range of specimens of different geologic ages, diversities, abundances, taxonomic compositions, depositional environments and taphonomic grades. The goal is for the students to identify all of the different fossil types to the lowest taxonomic level. I provide some that are well preserved and some that are highly fragmented making identification difficult. Next, students are tasked with assigning an age range of the sample by combining the age ranges of individual taxa, and make taphonomic descriptions and paleoecological analyses.

Boyer, Diana

184

A Fossil Thermometer  

NSDL National Science Digital Library

In this activity, students calculate temperatures during a time in the geologic record when rapid warming occurred using a well known method called 'leaf-margin analysis.' Students determine the percentage of the species that have leaves with smooth edges, as opposed to toothed, or jagged, edges. Facsimiles of fossil leaves from two collection sites are examined, categorized, and the data is plugged into an equation to provide an estimate of paleotemperature for two sites in the Bighorn Basin. It also introduces students to a Smithsonian scientist who worked on the excavation sites and did the analysis.

Institution, Smithsonian; Institute, Smithsonian

185

Oldest Homo and Pliocene biogeography of the Malawi Rift.  

PubMed

The Malawi Rift and Pliocene palaeofaunas, which include a hominid mandible attributed to Homo rudolfensis, provide a biogeographical link between the better known Plio-Pleistocene faunal records of East and Southern Africa. The Malawi Rift is in a latitudinal position suitable for recording any hominid and faunal dispersion towards the Equator that was brought on by increased aridity of the Late Pliocene African landscape. The evidence suggests that Pliocene hominids originated in the eastern African tropical domain and dispersed to southern Africa only during more favourable ecological circumstances. PMID:8413666

Schrenk, F; Bromage, T G; Betzler, C G; Ring, U; Juwayeyi, Y M

1993-10-28

186

Unearthing Important Fossils  

NSDL National Science Digital Library

Over the past several weeks, a flurry of dinosaur and other fossil discoveries have reached the mainstream news. From the two 530-million-year-old fish-like creatures that could be the earliest known vertebrates found in China, to the bones of two dinosaurs in Madagascar that may be the oldest dinosaurs ever found, to the "60-ton giraffe-like creature" (3) found in Oklahoma (called Sauroposeidon proteles, or "thunder lizard"), paleontologists are immersed in discovery. The significance of the first discovery is triggering excitement among paleontologists, worldwide. In particular, the discovery of the two "fish-like" fossils in China (to be published in this week's journal Nature) indicates that fish (i.e., vertebrates) evolved much earlier than previously thought and that "the rates of evolution in the oceans during the Cambrian period must have been exceptionally fast" (1). This week's In The News discusses some of the recently unveiled discoveries and provides background information and resources on vertebrate paleontology.

Payne, Laura X.

187

Fossil Microorganisms in Archaean  

NASA Technical Reports Server (NTRS)

Ancient Archean and Proterozoic rocks are the model objects for investigation of rocks comprising astromaterials. The first of Archean fossil microorganisms from Baltic shield have been reported at the last SPIE Conference in 2005. Since this confeence biomorphic structures have been revealed in Archean rocks of Karelia. It was determined that there are 3 types of such bion structures: 1. structures found in situ, in other words microorganisms even-aged with rock matrix, that is real Archean fossils biomorphic structures, that is to say forms inhabited early formed rocks, and 3. younger than Archean-Protherozoic minerali microorganisms, that is later contamination. We made attempt to differentiate these 3 types of findings and tried to understand of burial of microorganisms. The structures belongs (from our point of view) to the first type, or real Archean, forms were under examination. Practical investigation of ancient microorganisms from Green-Stone-Belt of Northern Karelia turns to be very perspective. It shows that even in such ancient time as Archean ancient diverse world existed. Moreover probably such relatively highly organized cyanobacteria and perhaps eukaryotic formes existed in Archean world.

Astafleva, Marina; Hoover, Richard; Rozanov, Alexei; Vrevskiy, A.

2006-01-01

188

Fossils, feet and the evolution of human bipedal locomotion  

PubMed Central

We review the evolution of human bipedal locomotion with a particular emphasis on the evolution of the foot. We begin in the early twentieth century and focus particularly on hypotheses of an ape-like ancestor for humans and human bipedal locomotion put forward by a succession of Gregory, Keith, Morton and Schultz. We give consideration to Morton's (1935) synthesis of foot evolution, in which he argues that the foot of the common ancestor of modern humans and the African apes would be intermediate between the foot of Pan and Hylobates whereas the foot of a hypothetical early hominin would be intermediate between that of a gorilla and a modern human. From this base rooted in comparative anatomy of living primates we trace changing ideas about the evolution of human bipedalism as increasing amounts of postcranial fossil material were discovered. Attention is given to the work of John Napier and John Robinson who were pioneers in the interpretation of Plio-Pleistocene hominin skeletons in the 1960s. This is the period when the wealth of evidence from the southern African australopithecine sites was beginning to be appreciated and Olduvai Gorge was revealing its first evidence for Homo habilis. In more recent years, the discovery of the Laetoli footprint trail, the AL 288-1 (A. afarensis) skeleton, the wealth of postcranial material from Koobi Fora, the Nariokotome Homo ergaster skeleton, Little Foot (Stw 573) from Sterkfontein in South Africa, and more recently tantalizing material assigned to the new and very early taxa Orrorin tugenensis, Ardipithecus ramidus and Sahelanthropus tchadensis has fuelled debate and speculation. The varying interpretations based on this material, together with changing theoretical insights and analytical approaches, is discussed and assessed in the context of new three-dimensional morphometric analyses of australopithecine and Homo foot bones, suggesting that there may have been greater diversity in human bipedalism in the earlier phases of our evolutionary history than previously suspected.

Harcourt-Smith, W E H; Aiello, L C

2004-01-01

189

Homo and Hetero-Assembly of Inorganic Nanoparticles  

NASA Astrophysics Data System (ADS)

This thesis describes the synthesis and assembly of metal and semiconductor nanoparticles (NPs). The two research topics include i) hetero-assembly of metal and semiconductor NPs, ii) effect of ionic strength on homo-assembly of gold nanorods (GNRs). First, we present hetero-assembly of GNRs and semiconductor quantum dots (QDs) in a chain using biotin-streptavidin interaction. We synthesized alloyed CdTeSe QDs and modified them with mercaptoundecanoic acid to render them water-soluble and to attach streptavidin. We synthesized GNRs by a seed-mediated method and selectively modified the ends with biotin. Hetero-assembly of QDs and GNRs depended on the size, ligands, and ratio of QDs and GNRs. Second, we controlled the rate of homo-assembly of GNRs by varying the ionic strength of the DMF/water solution. The solubility of polystyrene on the ends of GNRs depended on the ionic strength of the solution, which correlated with the rate of assembly of GNRs into chains.

Resetco, Cristina

190

Homo-Roche ester derivatives by asymmetric hydrogenation and organocatalysis.  

PubMed

Asymmetric hydrogenation routes to homologues of The Roche ester tend to be restricted to hydrogenations of itaconic acid derivatives, that is, substrates that contain a relatively unhindered, 1,1-disubstituted alkene. This is because in hydrogenations mediated by RhP2 complexes, the typical catalysts, it is difficult to obtain high conversions using the alternative substrate for the same product, the isomeric trisubstituted alkenes (D in the text). However, chemoselective modification of the identical functional groups in itaconic acid derivatives are difficult; hence, it would be favorable to use the trisubstituted alkene. Trisubstituted alkene substrates can be hydrogenated with high conversions using chiral analogs of Crabtree's catalyst of the type IrN(carbene). This paper demonstrates that such reactions are scalable (tens of grams) and can be manipulated to give optically pure homo-Roche ester chirons. Organocatalytic fluorination, chlorination, and amination of the homo-Roche building blocks was performed to demonstrate that they could easily be transformed into functionalized materials with two chiral centers and ?,?-groups that provide extensive scope for modifications. A synthesis of (S,S)- and (R,S)-?-hydroxyvaline was performed to illustrate one application of the amination product. PMID:24219839

Khumsubdee, Sakunchai; Zhou, Hua; Burgess, Kevin

2013-12-01

191

An enlarged parietal foramen in the late archaic Xujiayao 11 neurocranium from Northern China, and rare anomalies among Pleistocene Homo.  

PubMed

We report here a neurocranial abnormality previously undescribed in Pleistocene human fossils, an enlarged parietal foramen (EPF) in the early Late Pleistocene Xujiayao 11 parietal bones from the Xujiayao (Houjiayao) site, northern China. Xujiayao 11 is a pair of partial posteromedial parietal bones from an adult. It exhibits thick cranial vault bones, arachnoid granulations, a deviated posterior sagittal suture, and a unilateral (right) parietal lacuna with a posteriorly-directed and enlarged endocranial vascular sulcus. Differential diagnosis indicates that the perforation is a congenital defect, an enlarged parietal foramen, commonly associated with cerebral venous and cranial vault anomalies. It was not lethal given the individual's age-at-death, but it may have been associated with secondary neurological deficiencies. The fossil constitutes the oldest evidence in human evolution of this very rare condition (a single enlarged parietal foramen). In combination with developmental and degenerative abnormalities in other Pleistocene human remains, it suggests demographic and survival patterns among Pleistocene Homo that led to an elevated frequency of conditions unknown or rare among recent humans. PMID:23527224

Wu, Xiu-Jie; Xing, Song; Trinkaus, Erik

2013-01-01

192

An Enlarged Parietal Foramen in the Late Archaic Xujiayao 11 Neurocranium from Northern China, and Rare Anomalies among Pleistocene Homo  

PubMed Central

We report here a neurocranial abnormality previously undescribed in Pleistocene human fossils, an enlarged parietal foramen (EPF) in the early Late Pleistocene Xujiayao 11 parietal bones from the Xujiayao (Houjiayao) site, northern China. Xujiayao 11 is a pair of partial posteromedial parietal bones from an adult. It exhibits thick cranial vault bones, arachnoid granulations, a deviated posterior sagittal suture, and a unilateral (right) parietal lacuna with a posteriorly-directed and enlarged endocranial vascular sulcus. Differential diagnosis indicates that the perforation is a congenital defect, an enlarged parietal foramen, commonly associated with cerebral venous and cranial vault anomalies. It was not lethal given the individual’s age-at-death, but it may have been associated with secondary neurological deficiencies. The fossil constitutes the oldest evidence in human evolution of this very rare condition (a single enlarged parietal foramen). In combination with developmental and degenerative abnormalities in other Pleistocene human remains, it suggests demographic and survival patterns among Pleistocene Homo that led to an elevated frequency of conditions unknown or rare among recent humans.

Xing, Song

2013-01-01

193

A New Skull of Early Homo from Dmanisi, Georgia  

Microsoft Academic Search

Another hominid skull has been recovered at Dmanisi (Republic of Georgia) from the same strata in which hominid remains have been reported previously. The Dmanisi site dated to ~1.75 million years ago has now produced craniofacial portions of several hominid individuals, along with many well-preserved animal fossils and quantities of stone artifacts. Although there are certain anatomical differences among the

Abesalom Vekua; David Lordkipanidze; G. Philip Rightmire; Jordi Agusti; Reid Ferring; Givi Maisuradze; Alexander Mouskhelishvili; Medea Nioradze; Marcia Ponce de Leon; Martha Tappen; Merab Tvalchrelidze; Christoph Zollikofer

2002-01-01

194

Solar/fossil Rankine cooling  

SciTech Connect

A technical and economic review is provided of the hybrid solar/fossil solar cooling concept in which a dual energy input Rankine engine is used to drive a vapor compression chiller. In the Rankine engine a solar energy input is used to evaporate the water working fluid and fossil fuel is used to superheat the steam. 12 refs.

Curran, H.M.

1981-01-01

195

FOSSIL ENERGY AND FOOD SECURITY  

Microsoft Academic Search

To fulfil the basic goal of delivering food for the tables of the citizens, modern Western agriculture is extremely dependent on supporting material flows, infrastructure, and fossil energy. According to several observers, fossil fuel production is about to peak, i.e., oil extraction is no longer capable of keeping pace with the increasing demand. This situation may trigger an unprecedented increase

Folke Günther

2001-01-01

196

The first experimental approach to probing frontier orbitals and HOMO LUMO gap in bent metallocenes  

NASA Astrophysics Data System (ADS)

Combination of optical and electrochemical methods provided first experimental estimate of both HOMO and LUMO relative energies and HOMO-LUMO gap in organometallic ?-complexes. Energies of redox and optical HOMO-to-LUMO electron transitions in (?-L) 2MX 2 (Ti, Zr, Hf) linearly correlate viz. ELMCT? ?Eredox, Eem(0-0)? ?Eredox. Replacement of Cl - with Me - ?-ligands increases the HOMO-LUMO gap, predominantly, by destabilization introduced in the LUMO via Me-ligands; that is experimental justification for a hypothesis by Harrigan et al. [J. Organomet. Chem. 81 (1974) 79]. Effect of introduction of larger ?-ligands and a bridging group is progressive reduction of frontier orbitals energy gap.

Loukova, Galina V.

2002-02-01

197

Life of a Vertebrate Fossil  

NSDL National Science Digital Library

Unless you have a very large research grant, it can be difficult to find fossil bones. Fortunately, this very fine online learning module from the Smithsonian's Natural History Museum can help both young and old to learn about locating fossil bones, among other things. Through this multimedia feature created by the History Museum's department of paleobiology, visitors will learn what paleontologists do in each stage in the life of a vertebrate fossil. With the assistance of short video clips, interactive diagrams, and photographs, visitors will learn about how fossils are prepared for examination and how scientists unravel the stories of these paleontological finds. Finally, visitors will also learn how fossils are stored and preserved.

198

Fossil Energy Video Gallery  

DOE Data Explorer

DOE’s Office of Fossil Energy makes available an online video gallery to acquaint the public with its mission focus and activities. This is a list of the videos and the brief description that accompanies them. • An Introduction to Carbon Capture and Sequestration: FE's Carbon Sequestration Program is helping to develop technologies to capture, purify, and store carbon dioxide in order to reduce greenhouse gas emissions without adversely influencing energy use or hindering economic growth. Carbon sequestration technologies capture and store CO2 that would otherwise reside in the atmosphere for long periods of time. • SPR: The Energy Security of America (2009): Oil is only one aspect of the nation's Strategic Petroleum Reserve. See what it takes to run the world's largest underground crude oil storage facility. • Carbon Capture and Storage, 2008: In 2003, the Office of Fossil Energy's National Energy Technology Laboratory formed seven Regional Carbon Sequestration Partnerships to assess geologic formations suitable for carbon capture and storage, and determine the best approaches to implement carbon sequestration in each region. This video describes the work of these partnerships. • Geologic Carbon Sequestration: A Path Toward Zero Emission Energy from Coal: Carbon sequestration, the idea of capturing carbon dioxide before it is emitted to the atmosphere and storing it in underground rock formations or otherwise sequestering it, has progressed steadily over the past 10 years. It is now poised to become a key technology option for greenhouse gas emissions abatement. • Gasification û A Cornerstone Technology: The gasification process converts carbon-based materials such as coal into synthesis gas (syngas) that can be used to produce clean electrical energy, transportation fuels, and chemicals efficiently and cost-effectively. Gasification is a cornerstone technology of 21st century zero emissions powerplants. FE also provides links to several videos developed by their project partners. These are: • The CO2 Story Through Basin Electric • Carbon Capture and Storage at the Mountaineer Power Plants û American Electric Power • Hydrogen Energy California Project • Documentary Series (4 videos) from Prairie Public Broadcasting and the Plains CO2 Reduction (PCOR) Partnership • PCOR Partnership Video Clip Library

199

Lipin proteins form homo- and hetero-oligomers  

PubMed Central

SUMMARY Lipin family members (lipin 1, 2, 3) are bi-functional proteins that dephosphorylate phosphatidic acid (PA) to produce diacylglycerol (DAG) and act in the nucleus to regulate gene expression. Although other components of the triglyceride synthesis pathway can form oligomeric complexes, it is unknown whether lipin proteins also exist as oligomers. In this study, by using various approaches, we revealed that lipin 1 formed stable homo-oligomers with itself and hetero-oligomers with lipin 2/3. Both the N- and C-terminal regions of lipin 1 mediate its oligomerization in a head-to-head/tail-to-tail manner. We also show that lipin 1 subcellular localization can be influenced through oligomerization, and the individual lipin 1 monomers in the oligomer function independently in catalyzing dephosphorylation of PA. This study provides evidence that lipin proteins function as oligomeric complexes and that the three mammalian lipin isoforms can form combinatorial units.

Liu, Guang-Hui; Qu, Jing; Carmack, Anne E.; Kim, Hyun Bae; Chen, Chang; Ren, Hongmei; Morris, Andrew J.; Finck, Brian N.; Harris, Thurl E.

2011-01-01

200

Homo Heuristicus: Less-is-More Effects in Adaptive Cognition  

PubMed Central

Heuristics are efficient cognitive processes that ignore information. In contrast to the widely held view that less processing reduces accuracy, the study of heuristics shows that less information, computation, and time can in fact improve accuracy. We discuss some of the major progress made so far, focusing on the discovery of less-is-more effects and the study of the ecological rationality of heuristics which examines in which environments a given strategy succeeds or fails, and why. Homo heuristicus has a biased mind and ignores part of the available information, yet a biased mind can handle uncertainty more efficiently and robustly than an unbiased mind relying on more resource-intensive and general-purpose processing strategies.

Brighton, Henry; Gigerenzer, Gerd

2012-01-01

201

Crystal structure of Homo sapiens protein LOC79017  

SciTech Connect

LOC79017 (MW 21.0 kDa, residues 1-188) was annotated as a hypothetical protein encoded by Homo sapiens chromosome 7 open reading frame 24. It was selected as a target by the Center for Eukaryotic Structural Genomics (CESG) because it did not share more than 30% sequence identity with any protein for which the three-dimensional structure is known. The biological function of the protein has not been established yet. Parts of LOC79017 were identified as members of uncharacterized Pfam families (residues 1-95 as PB006073 and residues 104-180 as PB031696). BLAST searches revealed homologues of LOC79017 in many eukaryotes, but none of them have been functionally characterized. Here, we report the crystal structure of H. sapiens protein LOC79017 (UniGene code Hs.530024, UniProt code O75223, CESG target number go.35223).

Bae, Euiyoung; Bingman, Craig A.; Aceti, David J.; Phillips, Jr., George N. (UW)

2010-02-08

202

Brain shape in human microcephalics and Homo floresiensis  

PubMed Central

Because the cranial capacity of LB1 (Homo floresiensis) is only 417 cm3, some workers propose that it represents a microcephalic Homo sapiens rather than a new species. This hypothesis is difficult to assess, however, without a clear understanding of how brain shape of microcephalics compares with that of normal humans. We compare three-dimensional computed tomographic reconstructions of the internal braincases (virtual endocasts that reproduce details of external brain morphology, including cranial capacities and shape) from a sample of 9 microcephalic humans and 10 normal humans. Discriminant and canonical analyses are used to identify two variables that classify normal and microcephalic humans with 100% success. The classification functions classify the virtual endocast from LB1 with normal humans rather than microcephalics. On the other hand, our classification functions classify a pathological H. sapiens specimen that, like LB1, represents an ?3-foot-tall adult female and an adult Basuto microcephalic woman that is alleged to have an endocast similar to LB1's with the microcephalic humans. Although microcephaly is genetically and clinically variable, virtual endocasts from our highly heterogeneous sample share similarities in protruding and proportionately large cerebella and relatively narrow, flattened orbital surfaces compared with normal humans. These findings have relevance for hypotheses regarding the genetic substrates of hominin brain evolution and may have medical diagnostic value. Despite LB1's having brain shape features that sort it with normal humans rather than microcephalics, other shape features and its small brain size are consistent with its assignment to a separate species.

Falk, Dean; Hildebolt, Charles; Smith, Kirk; Morwood, M. J.; Sutikna, Thomas; Jatmiko; Saptomo, E. Wayhu; Imhof, Herwig; Seidler, Horst; Prior, Fred

2007-01-01

203

Submarine hydrothermal fossils confirmed  

NASA Astrophysics Data System (ADS)

Researchers from Princeton University (D. Crerrar et al, Econ. Geol., May 1982) have documented, in considerable detail, evidence for the formation of some of the 800 or more manganiferous chert deposits occurring in the central belt of the Fransiscan formation in northwestern California. They confirm the surprisingly old conclusion o f Tiaferro and Hudson (Cal. Div. Mines Bull., 125, 217-276, 1943) that the Fransiscan chert deposits probably represent the fossil remains of submarine hydrothermal vents.The deposits resemble recently discovered hydrothermal mounds near the Galapagos rift, the Gulf of Aden, and the Mid-Atlantic Ridge. As the Princeton investigators point out, there are important implications of the existence of deep hydrothermal circulation systems at oceanic spreading centers throughout geologic time. They note that the calculated annual flow of hydrothermal fluids in such processes is about 1017 g, which implies that the entire volume of the oceans could circulate completely every 10 million years. With such circulation, the hydrothermal processes along midocean ridges could control the composition of seawater and strongly influence the geochemical flux of elements in the marine environment.

Bell, Peter M.

204

Fossil fuel furnace reactor  

DOEpatents

A fossil fuel furnace reactor is provided for simulating a continuous processing plant with a batch reactor. An internal reaction vessel contains a batch of shale oil, with the vessel having a relatively thin wall thickness for a heat transfer rate effective to simulate a process temperature history in the selected continuous processing plant. A heater jacket is disposed about the reactor vessel and defines a number of independent controllable temperature zones axially spaced along the reaction vessel. Each temperature zone can be energized to simulate a time-temperature history of process material through the continuous plant. A pressure vessel contains both the heater jacket and the reaction vessel at an operating pressure functionally selected to simulate the continuous processing plant. The process yield from the oil shale may be used as feedback information to software simulating operation of the continuous plant to provide operating parameters, i.e., temperature profiles, ambient atmosphere, operating pressure, material feed rates, etc., for simulation in the batch reactor.

Parkinson, William J. (Los Alamos, NM)

1987-01-01

205

What More Is There to Say? Revisiting Agamben's Depiction of Homo Sacer  

Microsoft Academic Search

This article argues that Agamben's “paradigmatic method” leads to particular choices in his depiction of the figure of the homo sacer. Reviewing this project also suggests that there's more to history—the example given is the story of homo sacer—than Agamben's method would ever leave us to say. In other words, there are still resources in the tradition for something new,

Peter Gratton

2011-01-01

206

Cranial integration in Homo: singular warps analysis of the midsagittal plane in ontogeny and evolution  

Microsoft Academic Search

This study addresses some enduring issues of ontogenetic and evolutionary integration in the form of the hominid cranium. Our sample consists of 38 crania: 20 modern adult Homo sapiens, 14 subadult H. sapiens, and four archaic Homo. All specimens were CT-scanned except for two infant H. sapiens, who were imaged by MR instead. For each specimen 84 landmarks and semilandmarks

Fred L. Bookstein; Philipp Gunz; Philipp Mitterœcker; Hermann Prossinger; Katrin Schæfer; Horst Seidler

2003-01-01

207

Comparative morphological and morphometric description of the hominin calvaria from Bukuran (Sangiran, Central Java, Indonesia).  

PubMed

We describe the hominin skull (called here "Bukuran") discovered in the lower Kabuh (or "Bapang") series near Sendangbusik, from the Bukuran area in the Sangiran dome. The fossil, heavily mineralized, consists of the parieto-occipital and the left temporal, and the frontal bones. When combined, those two cranial parts represent a rather complete and well-preserved calvaria. Its stratigraphic position was established after the discovery. A detailed description is presented of the morphological and metric features of the Bukuran calvaria, and comparisons are made with Asian Homo erectus from Indonesia and China. The estimated cranial capacity of Bukuran, the general shape of its cranial vault, its ectocranial structures, and its morphological and metrical characters are in the range of Asian Homo erectus, and show clear affinities with other Indonesian members of the species. We discuss the evolutionary status of the Bukuran calvaria and its implication for hominin history on Java. PMID:23021728

Grimaud-Hervé, Dominique; Widianto, Harry; Détroit, Florent; Sémah, François

2012-11-01

208

Dating Fossil Pollen: A Simulation.  

ERIC Educational Resources Information Center

Describes a hands-on simulation in which students determine the age of "fossil" pollen samples based on the pollen types present when examined microscopically. Provides instructions for the preparation of pollen slides. (MDH)

Sheridan, Philip

1992-01-01

209

A new strategy for realizing the conversion of "homo-hetero-homo" heteroepitaxial growth in Bi(2)Te(3) and the thermoelectric performance.  

PubMed

Uncovering the reason for structure-dependent thermoelectric performance still remains a big challenge. A low-temperature and easily scalable strategy for synthesizing Bi2 Te3 nanostring hierarchical structures through solution-phase reactions, during which there is the conversion of "homo-hetero-homo" in Bi2 Te3 heteroepitaxial growth, is reported. Bi2 Te3 nanostrings are obtained through the transformation from pure Bi2 Te3 hexagonal nanosheets followed by Te?Bi2 Te3 "nanotop" heterostructures to Bi2 Te3 nanostrings. The growth of Bi2 Te3 nanostrings appears to be a self-assembly process through a wavy competition process generated from Te and Bi(3+) . The conversion of homo-hetero-homo opens up new platforms to investigate the wet chemistry of Bi2 Te3 nanomaterials. Furthermore, to study the effect of morphologies and hetero/homo structures, especially with the same origin and uniform conditions on their thermoelectric properties, the thermoelectric properties of Bi2 Te3 nanostrings and Te?Bi2 Te3 heterostructured pellets fabricated by spark plasma sintering have been investigated separately. PMID:24700422

Guo, Wei; Ma, Jianmin; Yang, Jiaqin; Li, Di; Qin, Qing; Wei, Caiying; Zheng, Wenjun

2014-05-01

210

Ontogenetic study of allometric variation in Homo and Pan mandibles.  

PubMed

Investigating ontogenetic variation and allometry in the mandible can provide valuable insight and aid in addressing questions related to the ontogeny of the skull. Here, patterns of ontogenetic shape change and allometric trajectories were examined in the mandible of 187 sub-adult and adult humans, bonobos, and chimpanzees. Procrustes-based geometric morphometrics was employed to quantify and analyze mandibular form. Thirty three-dimensional landmarks were used to capture the overall morphology of the mandible, and the landmarks were analyzed as a whole and subdivided into separate anterior and posterior units. Principal component analyses in Procrustes shape-space and form-space, and multivariate regressions were used to examine patterns of ontogenetic and allometric shape change. Results suggest that humans are distinct from Pan both in their mandibular morphology, particularly in the anterior-alveolar region, and direction of allometric trajectory. Chimpanzees and bonobos have parallel ontogenetic trajectories, but also show differences in mandibular shape. Species-specific features and adult mandibular shape are established before or by the eruption of the deciduous dentition. This suggests that developmental processes prior to deciduous teeth eruption have a stronger effect establishing taxa-specific phenotypes than later postnatal effects. This additionally implies that divergent trajectories between Pan and Homo do not contribute much to the adult mandibular shape after deciduous teeth eruption. Separate analyses of the anterior-alveolar region and ascending ramus show that these regions are semi-independent in their developmental pattern of shape change and allometry. This implies that allometric variation and ontogenetic shape change in the hominoid mandible is decoupled. PMID:24347386

Singh, Nandini

2014-02-01

211

Observe how fossils can form  

NSDL National Science Digital Library

This Earth science animation demonstrates the formation of a cast and mold fossil to middle and high school students. The introduction provides a brief description of the process. The animation shows how a shelled animal becomes buried in mud that eventually turns into stone. The shell dissolves and is replaced by minerals and, when the layers of rock are split, a cast and mold fossil is revealed. Movie controls allow students to repeat, pause, or step through the animation, which can give students more time to analyze the images. Copyright 2005 Eisenhower National Clearinghouse

Education, Terc. C.; Littell, Mcdougal

2003-01-01

212

FOSSIL2 energy policy model documentation: FOSSIL2 documentation  

SciTech Connect

This report discusses the structure, derivations, assumptions, and mathematical formulation of the FOSSIL2 model. Each major facet of the model - supply/demand interactions, industry financing, and production - has been designed to parallel closely the actual cause/effect relationships determining the behavior of the United States energy system. The data base for the FOSSIL2 program is large, as is appropriate for a system dynamics simulation model. When possible, all data were obtained from sources well known to experts in the energy field. Cost and resource estimates are based on DOE data whenever possible. This report presents the FOSSIL2 model at several levels. Volumes II and III of this report list the equations that comprise the FOSSIL2 model, along with variable definitions and a cross-reference list of the model variables. Volume II provides the model equations with each of their variables defined, while Volume III lists the equations, and a one line definition for equations, in a shorter, more readable format.

None

1980-10-01

213

Postnatal temporal bone ontogeny in Pan, Gorilla, and Homo, and the implications for temporal bone ontogeny in Australopithecus afarensis.  

PubMed

Assessments of temporal bone morphology have played an important role in taxonomic and phylogenetic evaluations of fossil taxa, and recent three-dimensional analyses of this region have supported the utility of the temporal bone for testing taxonomic and phylogenetic hypotheses. But while clinical analyses have examined aspects of temporal bone ontogeny in humans, the ontogeny of the temporal bone in non-human taxa is less well documented. This study examines ontogenetic allometry of the temporal bone in order to address several research questions related to the pattern and trajectory of temporal bone shape change during ontogeny in the African apes and humans. We further apply these data to a preliminary analysis of temporal bone ontogeny in Australopithecus afarensis. Three-dimensional landmarks were digitized on an ontogenetic series of specimens of Homo sapiens, Pan troglodytes, Pan paniscus, and Gorilla gorilla. Data were analyzed using geometric morphometric methods, and shape changes throughout ontogeny in relation to size were compared. Results of these analyses indicate that, despite broadly similar patterns, African apes and humans show marked differences in development of the mandibular fossa and tympanic portions of the temporal bone. These findings indicate divergent, rather than parallel, postnatal ontogenetic allometric trajectories for temporal bone shape in these taxa. The pattern of temporal bone shape change with size exhibited by A. afarensis showed some affinities to that of humans, but was most similar to extant African apes, particularly Gorilla. PMID:23868175

Terhune, Claire E; Kimbel, William H; Lockwood, Charles A

2013-08-01

214

Are the small human-like fossils found on Flores human endemic cretins?  

PubMed Central

Fossils from Liang Bua (LB) on Flores, Indonesia, including a nearly complete skeleton (LB1) dated to 18?kyr BP, were assigned to a new species, Homo floresiensis. We hypothesize that these individuals are myxoedematous endemic (ME) cretins, part of an inland population of (mostly unaffected) Homo sapiens. ME cretins are born without a functioning thyroid; their congenital hypothyroidism leads to severe dwarfism and reduced brain size, but less severe mental retardation and motor disability than neurological endemic cretins. We show that the fossils display many signs of congenital hypothyroidism, including enlarged pituitary fossa, and that distinctive primitive features of LB1 such as the double rooted lower premolar and the primitive wrist morphology are consistent with the hypothesis. We find that the null hypothesis (that LB1 is not a cretin) is rejected by the pituitary fossa size of LB1, and by multivariate analyses of cranial measures. We show that critical environmental factors were potentially present on Flores, how remains of cretins but not of unaffected individuals could be preserved in caves, and that extant oral traditions may provide a record of cretinism.

Obendorf, Peter J; Oxnard, Charles E; Kefford, Ben J

2008-01-01

215

Infrared Study of Electrochemically Prepared Homo and Mixed Polymer Films of Azulene,  

National Technical Information Service (NTIS)

Electrochemically formed homo-polyazulene and mixed polyazulene-polypyrrole films have been studied by infrared spectroscopy. Infrared spectra are consistent with a polymerization mechanism that involves loss of hydrogen atoms and produces an amorphous po...

R. Burzynski P. N. Prasad S. Bruckenstein J. W. Sharkey

1985-01-01

216

Craniofacial diversity in early Homo and the affinities of the Sterkfontein Valley  

Microsoft Academic Search

The Sterkfontein Valley specimens SK 847 (Swartkrans Member 1) and Stw 53 (Sterkfontein Member 5) provide important evidence\\u000a of earlyHomo in southern Africa. However, specific identity has been disputed, with that of SK 847 especially contentious. Opinions differ\\u000a markedly as to whether the specimens are conspecific or not, whether they should be referred to East African earlyHomo species, or whether

A. Bilsborough

2002-01-01

217

The First Humans: A Summary Perspective on the Origin and Early Evolution of the Genus Homo  

Microsoft Academic Search

Origin, adaptation and diversity are eternal themes in human evolution. These issues are equally timeless with respect to\\u000a our own lineage. Human paleontologists continue to grapple with questions surrounding the origin and early evolution of our\\u000a own genus. How do we identify the earliest members the genus Homo? How many species of Homo were there in the Pliocene and Pleistocene,

Frederick E. Grine; John G. Fleagle

218

Synthesis of Phytochelatins and Homo-Phytochelatins in Pisum sativum 1  

Microsoft Academic Search

In the roots of pea plants (Pisum sativum 1.) cultivated with 20 p~ CdCI, for 3 d, synthesis of phytochelatins (PCs or (yEC),C, where yEC is yglutamylcysteine and C is glycine) and homo- phytochelatins (h-PCs, (yEC),p-alaninel is accompanied by a dras- tic decrease in glutathione (CSH) content, but an increase in homo- glutathione (h-CSH) content. In contrast, the in vitro

Sigrid Klapheck; Sigrid Schlunz; Ludwig Bergmann

219

Comparative 3D quantitative analyses of trapeziometacarpal joint surface curvatures among living catarrhines and fossil hominins.  

PubMed

Comparisons of joint surface curvature at the base of the thumb have long been made to discern differences among living and fossil primates in functional capabilities of the hand. However, the complex shape of this joint makes it difficult to quantify differences among taxa. The purpose of this study is to determine whether significant differences in curvature exist among selected catarrhine genera and to compare these genera with hominin fossils in trapeziometacarpal curvature. Two 3D approaches are used to quantify curvatures of the trapezial and metacarpal joint surfaces: (1) stereophotogrammetry with nonuniform rational B-spline (NURBS) calculation of joint curvature to compare modern humans with captive chimpanzees and (2) laser scanning with a quadric-based calculation of curvature to compare modern humans and wild-caught Pan, Gorilla, Pongo, and Papio. Both approaches show that Homo has significantly lower curvature of the joint surfaces than does Pan. The second approach shows that Gorilla has significantly more curvature than modern humans, while Pongo overlaps with humans and African apes. The surfaces in Papio are more cylindrical and flatter than in Homo. Australopithecus afarensis resembles African apes more than modern humans in curvatures, whereas the Homo habilis trapezial metacarpal surface is flatter than in all genera except Papio. Neandertals fall at one end of the modern human range of variation, with smaller dorsovolar curvature. Modern human topography appears to be derived relative to great apes and Australopithecus and contributes to the distinctive human morphology that facilitates forceful precision and power gripping, fundamental to human manipulative activities. PMID:19544574

Marzke, M W; Tocheri, M W; Steinberg, B; Femiani, J D; Reece, S P; Linscheid, R L; Orr, C M; Marzke, R F

2010-01-01

220

Fossils and Leonardo da Vinci  

Microsoft Academic Search

IN his valuable and sympathetic appreciation of Huxley on the occasion of the centenary celebrations on May 4, Prof. Poulton incidentally referred to the puzzled discussions of naturalists of former days concerning the fossil sharks' teeth (``glossopetræ'') that were found in Italy.

Percy Edwin Spielmann

1925-01-01

221

Fossil Cetacea of the Caucasus.  

National Technical Information Service (NTIS)

The book by Guram Andreevich Mchedlidze, reviews in detail the fossil cetaceans of the Caucasus. It is based on rich collections from the author's own excavations, supplemented by those preserved in the museums at Tbilisi, etc. A study of the material hel...

G. A. Mchedlidze

1989-01-01

222

Progress of Fossil Fuel Science  

Microsoft Academic Search

Coal is the most abundant and widely distributed fossil fuel. More than 45% of the world's electricity is generated from coal, and it is the major fuel for generating electricity worldwide. The known coal reserves in the world are enough for more than 215 years of consumption, while the known oil reserves are only about 39 times of the world's

M. F. Demirbas

2007-01-01

223

The Oklo Fossil Fission Reactors  

NSDL National Science Digital Library

This web page gives an overview of the Oklo Fossil Fission Reactors, including the history of the area where the reactor is located, the science behind the nuclear reactions, and reasons for studying this nuclear reactor. This page also includes graphics describing the Physics behind the reactors, maps, and pictures of the reactor.

Loss, Robert

2012-06-15

224

Fossil Identification and Classification Lab  

NSDL National Science Digital Library

Students pick, sort, box, and identify fossils (mostly mollusks but also bryozoa, arthropods, cnidaria, and annelids) from richly fossiliferous, clastic marine sediment, compile a faunal list,compare the fauna with modern taxa, and make evaluate a paleogeographic model for the taxa found.

Willoughby, Ralph H.

225

Identifying Fossils: Exploring the Mississippi River Bluffs  

NSDL National Science Digital Library

This activity is a geology lab where students learn about fossils found in sedimentary rocks and show their understanding by writing a literary nonfiction paper from the perspective of one of those fossils.

226

ConcepTest: Best Index Fossil  

NSDL National Science Digital Library

Four outcrops of rock are examined in different locations of a state. The rock types and the fossils they contain are illustrated in the adjacent diagram. Which fossil would be the best choice to use as an index ...

227

Fossilization and Adaptation Activities in Paleontology  

NSDL National Science Digital Library

This activity introduces students to the concepts of time, past life, and fossils. After completing these exercises students will be able to evaluate the importance of fossils to our knowledge of past life, identify conditions necessary for fossilization, construct a possible scenario for formation of fossils, understand how organisms are adapted to their environments, and understand the relationships of modern and ancient communities with their environments.

Breithaupt, Brent

228

A surprise inside a T. Rex fossil  

NSDL National Science Digital Library

When scientists looked inside the leg bone of a recently discovered Tyrannosaurus rex fossil, they found something they weren't expecting. Typically, only the hard parts of an animal, like the bones, are preserved as fossils. This T. rex fossil, however, contained some beautifully preserved soft tissue inside the bone, where the marrow once was.

American Association for the Advancement of Science (AAAS;)

2005-03-24

229

Advanced Fossil Energy Technologies: Current reports  

Microsoft Academic Search

Advanced Fossil Energy Technologies (FET) is designed to keep fossil energy researchers informed of the latest scientific and technical reports in their area. The publication announces all DOE-sponsored reports and patent applications in the subject scope of fossil energy that have been received and processed into the Energy Data Base (EDB) in a two-week period prior to the publication date

Tamura

1988-01-01

230

Fossils in Antarctica: British Antarctic Survey  

NSDL National Science Digital Library

Although marching penguins add to Antarctica's allure, The British Antarctic Survey (BAS) has found fossil evidence that dinosaurs, marsupials, and forests inhabited the area long before penguins charmed the world with their trademark waddle. Since 1940, when the fossil collection of the BAS was started, it has grown to 40,000 specimens. The "Fossils" section of the BAS website can be found on the left side of the homepage in the "About Antarctica" area, and is divided into two explanatory sections: "Fossils from the Antarctic" and "Fossil Locations in Antarctica". There are also links in each section, near the top right hand corner of the page, to "Type and Figured Fossil Collection" and "Fossils Picture Gallery". In the "Fossils from the Antarctic" section, the types of fossils found are explained and include: molluscs, arthropods, echinoderms and plants. The "Fossil Locations in Antarctica" section has a map of the three islands where a large amount of fossils have been found, along with descriptions of each island and what general types of fossils have been found on them.

231

Cretaceous Fossils: Plants Quick Identification Gallery  

NSDL National Science Digital Library

This site forms a component of the CretaceousFossils.com page providing detailed information and high resolution photos of Cretaceous plants. The site supplies a practical, visual resource designed to facilitate identification of plant fossils from the Cretaceous Period. Educators and students alike may find this site and its links useful for viewing, identifying and downloading photos of exceptionally preserved fossil plant specimens.

Keith, Minor; Cretaceousfossils.com

232

Cycads: Fossil evidence of late paleozoic origin  

USGS Publications Warehouse

Plant fossils from Lower Permian strata of the southwestern United States have been interpreted as cycadalean megasporophylls. They are evidently descended from spermopterid elements of the Pennsylvanian Taeniopteris complex; thus the known fossil history of the cycads is extended from the Late Triassic into the late Paleozoic. Possible implications of the Permian fossils toward evolution of the angiosperm carpel are considered.

Mamay, S. H.

1969-01-01

233

Looking at Fossils in New Ways  

ERIC Educational Resources Information Center

Existing fossils could be studied from a different prospective with the use of new methods of analysis for gathering more information. The new techniques of studying fossils binds the new and the old techniques and information and provides another way to look at fossils.

Flannery, Maura C.

2005-01-01

234

Paleomagnetic dates of hominid remains from Yuanmou, China, and other Asian sites.  

PubMed

Two hominid upper central incisors found in the Yuanmou Basin in southwest China in 1965 have affinities with Homo erectus fossils from Zhoukoudian, but exhibit primitive features. The Yuanmou hominid remains are alleged to be coeval with or older than African specimens dated at about 1.8 m.y.a. Recent age refinements of geomagnetic short reversal events and excursions permit assigning the Yuanmou hominid-bearing bed to the early Brunhes chron (about 0.7 m.y.a.). Magnetochronological assessments confirm that the Lantian calotte which has been dated to about 1.2 m.y.a., is the oldest reliable evidence for the emergence of Homo in eastern Asia as well as China, and that hominid fossils from Sangiran and Mojokerto, Java, do not exceed 1.1 Ma in age. These results refute the view that the genus Homo migrated into eastern Asia in the late Pliocene or the earliest Pleistocene. PMID:12098208

Hyodo, Masayuki; Nakaya, Hideo; Urabe, Atsushi; Saegusa, Haruo; Shunrong, Xue; Jiyun, Yin; Xuepin, Ji

2002-07-01

235

FOSSIL SPRINGS ROADLESS AREA, ARIZONA.  

USGS Publications Warehouse

Based on field studies, the Fossil Springs Roadless Area in central Arizona is concluded to have little promise for the occurrence of mineral or energy resources. Rocks in the Supai Formation (Pennsylvanian-Permian) near the central part of the roadless area contain widespread but spotty copper mineralization and trace amounts of uranium. Analyses obtained during the study define geochemical anomalies in two portions of the area that remain unexplained. The suites of anomalous metals suggest the possibility of hydrothermal veins and the presence of ultramafic rocks; neither were found in the field. Although there is little promise for the occurrence of mineral resources in the Fossil Springs Roadless Area, studies to identify the source of the geochemical anomalies could have valuable implications for regional studies and mineral exploration in the surrounding area.

Beard, L. S.; Ellis, C. E.

1984-01-01

236

Extinction and the fossil record  

NASA Technical Reports Server (NTRS)

The author examines evidence of mass extinctions in the fossil record and searches for reasons for such large extinctions. Five major mass extinctions eliminated at least 40 percent of animal genera in the oceans and from 65 to 95 percent of ocean species. Questions include the occurrence of gradual or catastrophic extinctions, causes, environment, the capacity of a perturbation to cause extinctions each time it happens, and the possibility and identification of complex events leading to a mass extinction.

Sepkoski, J. J. Jr; Sepkoski JJ, ,. J. r. (Principal Investigator)

1994-01-01

237

Dinosaurs: Ancient Fossils, New Discoveries  

NSDL National Science Digital Library

This Web site, created to complement the Museum's Dinosaurs: Ancient Fossils, New Discoveries exhibit, offers a virtual visit to the Museum, complete with text, photos, video clips, audio interviews, and more and includes much of the information which was in the original exhibit which is now closed. The site includes information on the bio-mechanics of dinosaurs and the reasons behind some of their strange appearances.

238

Microbial denitrogenation of fossil fuels.  

PubMed

The microbial degradation of nitrogen compounds from fossil fuels is important because of the contribution these contaminants make to the formation of nitrogen oxides (NOx) and hence to air pollution and acid rain. They also contribute to catalyst poisoning during the refining of crude oil, thus reducing process yields. We review the current status of microbial degradation of aromatic nitrogen compounds and discuss the potential of microbial processes to alleviate these problems. PMID:9744113

Benedik, M J; Gibbs, P R; Riddle, R R; Willson, R C

1998-09-01

239

Extinction and the fossil record.  

PubMed

The author examines evidence of mass extinctions in the fossil record and searches for reasons for such large extinctions. Five major mass extinctions eliminated at least 40 percent of animal genera in the oceans and from 65 to 95 percent of ocean species. Questions include the occurrence of gradual or catastrophic extinctions, causes, environment, the capacity of a perturbation to cause extinctions each time it happens, and the possibility and identification of complex events leading to a mass extinction. PMID:11539586

Sepkoski, J J

1994-03-01

240

Fossil Collection and Museum Curation  

NSDL National Science Digital Library

Before we go into the field, students are exposed to field collection techniques and appropriate information to collect at the outcrop. This assignment is good for field trips because students each collect 1 or few samples, but spend time on the outcrop measuring a section and collecting associated lithologic and other fossil data if available (locality information, exposure, over and underlying sedimentology, details of host rock, sedimentary structures, assocaited fossils, diversity and abundance, taphonomic condition of fossils, etc). The field locality can be anywhere where there are resaonably well preserved fossils (and should give students an appreciation of museum quality specimens). This allows this exercise to be flexible as field trip localities change. All of the information that they collect in the field will be included in their field notebook that is handed in at the end of the field trip for evaluation. In the lab-I used class time-students are asked to make a detailed sketch of their sample that they can take to the library with them, and a discussion is held as to where to look for information to identify specimens with. Students are given a week (variable depending on the availability of resources, for example if monographs need to be aquired through inter-library loan) to idenitfy their specimen and then asked to catalog them for the museum. They fill out a SUNY Oswego Paleontology Museum card, which they have seen all semester for their sample and are given the option to donate it to the collection or keep it.

Boyer, Diana

241

Neanderthals: fossil evidence and DNA.  

PubMed

Neanderthals inhabited Western Eurasia from approximately 300 to 30 thousand years ago (ka). They are distinguished by a unique combination of anatomical traits, and are commonly associated with Middle Paleolithic lithic industries. Current consensus among paleoanthropologists is that they represented a separate Eurasian human lineage, which evolved in isolation from the rest of the Old World and which shared a common ancestor with modern humans in the Middle Pleistocene. It is thought that some aspects of the distinctive Neanderthal anatomy evolved in response to selection related to the extreme cold of the European glacial cycles. Nevertheless, genetic drift seems to be partially responsible for the evolution of these traits. The last appearance of Neanderthals in the fossil record ca. 30 ka BP dates a few millennia after the first appearance of modern humans in Europe. The retrieval of ancient mitochondrial and, more recently, nuclear DNA from Neanderthal fossil puts us in the unique position to combine fossil with genetic evidence to address questions about their evolution, paleobiology and eventual fate. PMID:21957644

Harvati, Katerina

2011-01-01

242

THE NATURE OF FOSSIL GALAXY GROUPS: ARE THEY REALLY FOSSILS?  

SciTech Connect

We use SDSS-DR4 photometric and spectroscopic data out to redshift z {approx} 0.1 combined with ROSAT All Sky Survey X-ray data to produce a sample of 25 fossil groups (FGs), defined as bound systems dominated by a single, luminous elliptical galaxy with extended X-ray emission. We examine possible biases introduced by varying the parameters used to define the sample, and the main pitfalls are also discussed. The spatial density of FGs, estimated via the V/V {sub MAX} test, is 2.83 x 10{sup -6} h {sup 3} {sub 75} Mpc{sup -3} for L{sub X} > 0.89 x 10{sup 42} h {sup -2} {sub 75} erg s{sup -1} consistent with Vikhlinin et al., who examined an X-ray overluminous elliptical galaxy sample (OLEG). We compare the general properties of FGs identified here with a sample of bright field ellipticals generated from the same data set. These two samples show no differences in the distribution of neighboring faint galaxy density excess, distance from the red sequence in the color-magnitude diagram, and structural parameters such as a {sub 4} and internal color gradients. Furthermore, examination of stellar populations shows that our 25 FGs have similar ages, metallicities, and {alpha}-enhancement as the bright field ellipticals, undermining the idea that these systems represent fossils of a physical mechanism that occurred at high redshift. Our study reveals no difference between FGs and field ellipticals, suggesting that FGs might not be a distinct family of true fossils, but rather the final stage of mass assembly in the universe.

La Barbera, F.; Sorrentino, G. [INAF-Osservatorio Astronomico di Capodimonte, Via Moiariello 16, 80131 Napoli (Italy); De Carvalho, R. R. [VSTceN, via Moiariello 16, 80131 Napoli (Italy); De la Rosa, I. G. [Instituto de Astrofisica de Canarias, Tenerife (Spain); Gal, R. R. [Institute for Astronomy, 2680 Woodlawn Dr., Honolulu, HI 96822 (United States); Kohl-Moreira, J. L. [Observatorio Nacional, Rua General Jose Cristino 77, Rio de Janeiro (Brazil)

2009-04-15

243

Inferring hominoid and early hominid phylogeny using craniodental characters: the role of fossil taxa.  

PubMed

Recent discoveries of new fossil hominid species have been accompanied by several phylogenetic hypotheses. All of these hypotheses are based on a consideration of hominid craniodental morphology. However, Collard and Wood (2000) suggested that cladograms derived from craniodental data are inconsistent with the prevailing hypothesis of ape phylogeny based on molecular data. The implication of their study is that craniodental characters are unreliable indicators of phylogeny in hominoids and fossil hominids but, notably, their analysis did not include extinct species. We report here on a cladistic analysis designed to test whether the inclusion of fossil taxa affects the ability of morphological characters to recover the molecular ape phylogeny. In the process of doing so, the study tests both Collard and Wood's (2000) hypothesis of character reliability, and the several recently proposed hypotheses of early hominid phylogeny. One hundred and ninety-eight craniodental characters were examined, including 109 traits that traditionally have been of interest in prior studies of hominoid and early hominid phylogeny, and 89 craniometric traits that represent size-corrected linear dimensions measured between standard cranial landmarks. The characters were partitioned into two data sets. One set contained all of the characters, and the other omitted the craniometric characters. Six parsimony analyses were performed; each data set was analyzed three times, once using an ingroup that consisted only of extant hominoids, a second time using an ingroup of extant hominoids and extinct early hominids, and a third time excluding Kenyanthropus platyops. Results suggest that the inclusion of fossil taxa can play a significant role in phylogenetic analysis. Analyses that examined only extant taxa produced most parsimonious cladograms that were inconsistent with the ape molecular tree. In contrast, analyses that included fossil hominids were consistent with that tree. This consistency refutes the basis for the hypothesis that craniodental characters are unreliable for reconstructing phylogenetic relationships. Regarding early hominids, the relationships of Sahelanthropus tchadensis and Ardipithecus ramidus were relatively unstable. However, there is tentative support for the hypotheses that S. tchadensis is the sister taxon of all other hominids. There is support for the hypothesis that A. anamensis is the sister taxon of all hominids except S. tchadensis and Ar. ramidus. There is no compelling support for the hypothesis that Kenyanthropus platyops shares especially close affinities with Homo rudolfensis. Rather, K. platyops is nested within the Homo + Paranthropus + Australopithecus africanus clade. If K. platyops is a valid species, these relationships suggest that Homo and Paranthropus are likely to have diverged from other hominids much earlier than previously supposed. There is no support for the hypothesis that A. garhi is either the sister taxon or direct ancestor of the genus Homo. Phylogenetic relationships indicate that Australopithecus is paraphyletic. Thus, A. anamensis and A. garhi should be allocated to new genera. PMID:15566946

Strait, David S; Grine, Frederick E

2004-12-01

244

Late Pliocene Homo and hominid land use from Western Olduvai Gorge, Tanzania.  

PubMed

Excavation in the previously little-explored western portion of Olduvai Gorge indicates that hominid land use of the eastern paleobasin extended at least episodically to the west. Finds included a dentally complete Homo maxilla (OH 65) with lower face, Oldowan stone artifacts, and butchery-marked bones dated to be between 1.84 and 1.79 million years old. The hominid shows strong affinities to the KNM ER 1470 cranium from Kenya (Homo rudolfensis), a morphotype previously unrecognized at Olduvai. ER 1470 and OH 65 can be accommodated in the H. habilis holotype, casting doubt on H. rudolfensis as a biologically valid taxon. PMID:12595689

Blumenschine, Robert J; Peters, Charles R; Masao, Fidelis T; Clarke, Ronald J; Deino, Alan L; Hay, Richard L; Swisher, Carl C; Stanistreet, Ian G; Ashley, Gail M; McHenry, Lindsay J; Sikes, Nancy E; Van Der Merwe, Nikolaas J; Tactikos, Joanne C; Cushing, Amy E; Deocampo, Daniel M; Njau, Jackson K; Ebert, James I

2003-02-21

245

Evolution and the Fossil Record  

NSDL National Science Digital Library

This publication of the American Geological Institute is a non-technical introduction to evolution and aims to help the general public gain a better understanding of one of the fundamental underlying concepts of modern science. Concepts covered include geologic time, change through time, Darwin's theory of evolution, evolution as a mechanism for change, the nature of species, the nature of theory, paleontology, and determination of age. Four case studies highlight examples of evolution from the fossil record to provide a perspective for understanding the evolution of life on Earth.

Springer, Dale; Pojeta Jr., John

2007-12-12

246

Fossil energy program. Summary document  

SciTech Connect

This program summary document presents a comprehensive overview of the research, development, and demonstration (RD and D) activities that will be performed in FY 1981 by the Assistant Secretary for Fossil Energy (ASFE), US Department of Energy (DOE). The ASFE technology programs for the fossil resources of coal, petroleum (including oil shale) and gas have been established with the goal of making substantive contributions to the nation's future supply and efficienty use of energy. On April 29, 1977, the Administration submitted to Congress the National Energy Plan (NEP) and accompanying legislative proposals designed to establish a coherent energy policy structure for the United States. Congress passed the National Energy Act (NEA) on October 15, 1978, which allows implementation of the vital parts of the NEP. The NEP was supplemented by additional energy policy statements culminating in the President's address on July 15, 1979, presenting a program to further reduce dependence on imported petroleum. The passage of the NEA-related energy programs represent specific steps by the Administration and Congress to reorganize, redirect, and clarify the role of the Federal Government in the formulation and execution of national energy policy and programs. The energy technology RD and D prog4rams carried out by ASFE are an important part of the Federal Government's effort to provide the combination and amounts of energy resources needed to ensure national security and continued economic growth.

None

1980-05-01

247

The fossil record of the Peronosporomycetes (Oomycota).  

PubMed

Evidence of fossil Peronosporomycetes has been slow to accumulate. In this review various fossils historically assigmed to the Peronosporomycets are dicussed briefly and an explanation is provided as to why the fossil record of this grouop has remained inconsistent. In recent year there has been several new reports of fossil peronosporomycetes based on structurally preserved oogonium-antheridium complexes from Derovonian and Carboniferous rocks that demonstrate the existence of these organisms as fossils and refute the long-standing assumption that they are too delicate to be preserved. Among these are serral tyoes characterized by oogonial surface members of the group. To date at last three groups of fossil vascular plants (i.e. lycophytes, ferns and seed ferns) are known to host peronosporomycetes aas endophytes; however only one form has been identified as a parasite. PMID:21289104

Krings, Michael; Taylor, Thomas N; Dotzler, Nora

2011-01-01

248

Fossil energy biotechnology: A research needs assessment  

NASA Astrophysics Data System (ADS)

The Office of Program Analysis of the U.S. Department of Energy commissioned this study to evaluate and prioritize research needs in fossil energy biotechnology. The objectives were to identify research initiatives in biotechnology that offer timely and strategic options for the more efficient and effective uses of the Nation's fossil resource base, particularly the early identification of new and novel applications of biotechnology for the use or conversion of domestic fossil fuels. Fossil energy biotechnology consists of a number of diverse and distinct technologies, all related by the common denominator -- biocatalysis. The expert panel organized 14 technical subjects into three interrelated biotechnology programs: (1) upgrading the fuel value of fossil fuels; (2) bioconversion of fossil feedstocks and refined products to added value chemicals; and (3) the development of environmental management strategies to minimize and mitigate the release of toxic and hazardous petrochemical wastes.

1993-11-01

249

L’architecture de l’épaule au sein du genre Homo : nouvelles interprétations  

Microsoft Academic Search

The morphology of human clavicles can be estimated by projecting them on two perpendicular planes in order to assess the shapes of their cranial and dorsal primary curvatures. In cranial view no differences in curvature appear within the genus Homo, which means the different species had similar arms elevation capacity, especially in protraction. On the contrary, in dorsal view two

Jean-Luc Voisin

2010-01-01

250

Female Condition Influences Preferences for Sexual Dimorphism in Faces of Male Humans (Homo sapiens )  

Microsoft Academic Search

In some species, female condition correlates positively with preferences for male secondary sexual traits. Women's preferences for sexually dimorphic characteristics in male faces (facial masculinity) have recently been reported to covary with self-reported attractiveness. As women's attractiveness has been proposed to signal reproductive condition, the findings in human (Homo sapiens) and other species may reflect similar processes. The current study

I. S. Penton-Voak; A. C. Little; B. C. Jones; D. M. Burt; B. P. Tiddeman; D. I. Perrett

2003-01-01

251

Chemical synthesis of polyaspartates: a biodegradable alternative to currently used polycar?ylate homo- and copolymers  

Microsoft Academic Search

In order to improve the environmental acceptability of water-soluble sequestrants and dispersants that can end up in the surface water, new alternatives to the currently used polycar?ylate homo- and copolymers are needed. One alternative might be polyaspartates, a group of acidic polyamides. These polymers, which are functional equivalents of existing products, are biodegradable. They can be used in many different

Michael Schwamborn

1998-01-01

252

Spatial Construction Skills of Chimpanzees ("Pan Troglodytes") and Young Human Children ("Homo Sapiens Sapiens")  

ERIC Educational Resources Information Center

Spatial construction tasks are basic tests of visual-spatial processing. Two studies have assessed spatial construction skills in chimpanzees (Pan troglodytes) and young children (Homo sapiens sapiens) with a block modelling task. Study 1a subjects were three young chimpanzees and five adult chimpanzees. Study 1b subjects were 30 human children…

Poti, Patrizia; Hayashi, Misato; Matsuzawa, Tetsuro

2009-01-01

253

Greater Emphasis on Female Attractiveness in Homo sapiens: A Revised Solution to an Old Evolutionary Riddle  

Microsoft Academic Search

Substantial evidence from psychology and cross-cultural anthropology supports a general rule of greater emphasis on female physical attractiveness in Homo sapiens. As sensed by Darwin (1871) and clarified by Trivers (1972), generally higher female parental investment is a key determinant of a common pattern of sexual selection in which male animals are more competitive, more eager sexually and more conspicuous

Jonathan Gottschall

254

Selective oxidative homo- and cross-coupling of phenols with aerobic catalysts.  

PubMed

Simple catalysts that use atom-economical oxygen as the terminal oxidant to accomplish selective ortho-ortho, ortho-para, or para-para homo-couplings of phenols are described. In addition, chromium salen catalysts have been discovered as uniquely effective in the cross-coupling of different phenols with high chemo- and regioselectivity. PMID:24797179

Lee, Young Eun; Cao, Trung; Torruellas, Carilyn; Kozlowski, Marisa C

2014-05-14

255

Fossilization Processes in Thermal Springs  

NASA Technical Reports Server (NTRS)

To create a comparative framework for the study of ancient examples, we have been carrying out parallel studies of the microbial biosedimentology, taphonomy and geochemistry of modem and sub-Recent thermal spring deposits. One goal of the research is the development of integrated litho- and taphofacies models for siliceous and travertline sinters. Thermal springs are regarded as important environments for the origin and early evolution of life on Earth, and we seek to utilize information from the fossil record to reconstruct the evolution of high temperature ecosystems. Microbial contributions to the fabric of thermal spring sinters occur when population growth rates keep pace with, or exceed rates of inorganic precipitation, allowing for the development of continuous biofilms or mats. In siliceous thermal springs, microorganisms are typically entombed while viable. Modes of preservation reflect the balance between rates of organic matter degradation, silica precipitation and secondary infilling. Subaerial sinters are initially quite porous and permeable and at temperatures higher than about 20 C, organic materials are usually degraded prior to secondary infilling of sinter frameworks. Thus, organically-preserved microfossils are rare and fossil information consists of characteristic biofabrics formed by the encrustation and underplating of microbial mat surfaces. This probably accounts for the typically low total organic carbon values observed in thermal spring deposits. In mid-temperature, (approx. 35 - 59 C) ponds and outflows, the surface morphology of tufted Phormidium mats is preserved through mat underplating by thin siliceous: crusts. Microbial taxes lead to clumping of ceils and/or preferred filament orientations that together define higher order composite fabrics in thermal spring stromatolites (e.g. network, coniform, and palisade). At lower temperatures (less than 35 C), Calothrix mats cover shallow terracette pools forming flat carpets or pustular surfaces that produce palisade and "shrub" fabrics, respectively. At finer scales, composite fabrics are seen to consist distinctive associations of microstructures formed by the encrustation of individual cells and filaments. Composite fabrics survive the diagenetic transitions from primary opaline silica to quartz and are known from subaerial thermal spring deposits as old as Lower Carboniferous. However, fossil microorganisms tend to be rare in older deposits, and are usually preserved only where cells or sheaths have been stained by iron oxides. In subaqueous mineralizing springs at lower temperatures, early infilling leads to a more rapid and complete reduction in porosity and permeability. This process, along with the slower rates of microbial degradation at lower temperatures, creates a more favorable situation for organic matter preservation. Application of this taphonomic model to the Rhynie Chert, previously interpreted as subaerial, suggest it was probably deposited in a subaqueous spring setting at lower temperatures.

Farmer, Jack D.; Cady, Sherry; Desmarais, David J.; Chang, Sherwood (Technical Monitor)

1995-01-01

256

Deoxygenation in cycling fossil plants  

SciTech Connect

In a previous EPRI study (Phase 1 of RP1184-9) at the Port Everglades plant of Florida Power and Light, it was demonstrated that minimizing shutdown oxygen levels at a cycling plant could reduce corrosion product transport to the boilers. A continuation of the program was performed to demonstrate the use of two forms of activated carbon to catalyze the hydrazine/oxygen reaction as a method to minimize the oxygen levels of cycling fossil plants. An activated carbon impregnated fiber overlay on a powdered resin precoat was tested at TU Electric's Tradinghouse Creek Unit 1 and a carbon bed followed by a deep bed demineralizer was tested at Duquesne's Elrama Unit 4. The improvement in attainable oxygen control was demonstrated and the effect on corrosion product transport during cyclic operation was evaluated. The study also demonstrated the application of a data acquisition system for prompt data assessment, control of chemical additions, identification of problems, and development of responsive corrective actions.

Pearl, W.L.; Hobart, R.L.; Hook, T.A.; McNea, D.A. (NWT Corp., San Jose, CA (United States))

1992-04-01

257

Fossil diatoms and neogene paleolimnology  

USGS Publications Warehouse

Diatoms have played an important role in the development of Neogene continental biostratigraphy and paleolimnology since the mid-19th Century. The history of progress in Quaternary diatom biostratigraphy has developed as a result of improved coring techniques that enable sampling sediments beneath existing lakes coupled with improved chronological control (including radiometric dating and varve enumeration), improved statistical treatment of fossil diatom assemblages (from qualitative description to influx calculations of diatom numbers or volumes), and improved ecological information about analogous living diatom associations. The last factor, diatom ecology, is the most critical in many ways, but progresses slowly. Fortunately, statistical comparison of modern diatom assemblages and insightful studies of the nutrient requirements of some common freshwater species are enabling diatom paleolimnologists to make more detailed interpretations of the Quaternary record than had been possible earlier, and progress in the field of diatom biology and ecology will continue to refine paleolimnological studies. The greater age and geologic setting of Tertiary diatomaceous deposits has prompted their study in the contexts of geologic history, biochronology and evolution. The distribution of diatoms of marine affinities in continental deposits has given geologists insights about tectonism and sea-level change, and the distribution of distinctive (extinct?) diatoms has found utilization both in making stratigraphic correlations between outcrops of diatomaceous deposits and in various types of biochronological studies that involve dating deposits in different areas. A continental diatom biochronologic scheme will rely upon evolution, such as the appearance of new genera within a family, in combination with regional environmental changes that are responsible for the wide distribution of distinctive diatom species. The increased use of the scanning electron microscope for the detailed descriptions of fossil diatoms will provide the basis for making more accurate correlations and identifications, and the micromorphological detail for speculations about evolutionary relationships. ?? 1988.

Platt, Bradbury, J.

1988-01-01

258

Fossil fuel usage and the environment  

Microsoft Academic Search

The Greenhouse Effect and global warming, ozone formation in the troposphere, ozone destruction in the stratosphere, and acid rain are important environmental issues. The relationship of fossil fuel usage to some of these issues is discussed. Data on fossil fuel consumption and the sources and sinks of carbon dioxide, carbon monoxide, methane, nitrogen and sulfur oxides, and ozone indicate that

Klass

1990-01-01

259

Do alternative energy sources displace fossil fuels?  

NASA Astrophysics Data System (ADS)

A fundamental, generally implicit, assumption of the Intergovernmental Panel on Climate Change reports and many energy analysts is that each unit of energy supplied by non-fossil-fuel sources takes the place of a unit of energy supplied by fossil-fuel sources. However, owing to the complexity of economic systems and human behaviour, it is often the case that changes aimed at reducing one type of resource consumption, either through improvements in efficiency of use or by developing substitutes, do not lead to the intended outcome when net effects are considered. Here, I show that the average pattern across most nations of the world over the past fifty years is one where each unit of total national energy use from non-fossil-fuel sources displaced less than one-quarter of a unit of fossil-fuel energy use and, focusing specifically on electricity, each unit of electricity generated by non-fossil-fuel sources displaced less than one-tenth of a unit of fossil-fuel-generated electricity. These results challenge conventional thinking in that they indicate that suppressing the use of fossil fuel will require changes other than simply technical ones such as expanding non-fossil-fuel energy production.

York, Richard

2012-06-01

260

Accuracy of Fossils and Dating Methods  

NSDL National Science Digital Library

The issue-focused, peer-reviewed article asserts that fossil dating is accurate because the method follows strict scientific guidelines: the age of rocks around a fossil can be considered, mathematical calculations are used, the state of decay, carbon-14, and isotopes figure in calculations, and tree of life relationships often help sort the dates.

Michael Benton (University of Bristol, UK;)

2001-01-01

261

The original colours of fossil beetles  

PubMed Central

Structural colours, the most intense, reflective and pure colours in nature, are generated when light is scattered by complex nanostructures. Metallic structural colours are widespread among modern insects and can be preserved in their fossil counterparts, but it is unclear whether the colours have been altered during fossilization, and whether the absence of colours is always real. To resolve these issues, we investigated fossil beetles from five Cenozoic biotas. Metallic colours in these specimens are generated by an epicuticular multi-layer reflector; the fidelity of its preservation correlates with that of other key cuticular ultrastructures. Where these other ultrastructures are well preserved in non-metallic fossil specimens, we can infer that the original cuticle lacked a multi-layer reflector; its absence in the fossil is not a preservational artefact. Reconstructions of the original colours of the fossils based on the structure of the multi-layer reflector show that the preserved colours are offset systematically to longer wavelengths; this probably reflects alteration of the refractive index of the epicuticle during fossilization. These findings will allow the former presence, and original hue, of metallic structural colours to be identified in diverse fossil insects, thus providing critical evidence of the evolution of structural colour in this group.

McNamara, Maria E.; Briggs, Derek E. G.; Orr, Patrick J.; Noh, Heeso; Cao, Hui

2012-01-01

262

Proposed Fossil Butte National Monument, Wyoming.  

National Technical Information Service (NTIS)

The Department of the Interior, National Park Service proposes the establishment of Fossil Butte National Monument, 8180 acres, to preserve the greatest concentrations of fossilized fresh-water fish in the nation and one of the few such repositories in th...

1973-01-01

263

The First Fossil Record of Caecilian Amphibians  

Microsoft Academic Search

THREE groups of amphibians are living today-frogs, salamanders and caecilians. The fossil record of frogs and salamanders is relatively poor1,2, but representatives of most groups have been discovered. For the caecilians, however, no authentic fossils have been recognized, until now. We describe here a single diagnostic vertebra from the Palaeocene of Brazil.

Richard Estes; MARVALEE H. WAKE

1972-01-01

264

Atomic force microscopy of Precambrian microscopic fossils.  

PubMed

Atomic force microscopy (AFM) is a technique used routinely in material science to image substances at a submicron (including nm) scale. We apply this technique to analysis of the fine structure of organic-walled Precambrian fossils, microscopic sphaeromorph acritarchs (cysts of planktonic unicellular protists) permineralized in approximately 650-million-year-old cherts of the Chichkan Formation of southern Kazakhstan. AFM images, backed by laser-Raman spectroscopic analysis of individual specimens, demonstrate that the walls of these petrified fossils are composed of stacked arrays of approximately 200-nm-sized angular platelets of polycyclic aromatic kerogen. Together, AFM and laser-Raman spectroscopy provide means by which to elucidate the submicron-scale structure of individual microscopic fossils, investigate the geochemical maturation of ancient organic matter, and, potentially, distinguish true fossils from pseudofossils and probe the mechanisms of fossil preservation by silica permineralization. PMID:12089337

Kempe, André; Schopf, J William; Altermann, Wladyslaw; Kudryavtsev, Anatoliy B; Heckl, Wolfgang M

2002-07-01

265

Atomic force microscopy of Precambrian microscopic fossils  

PubMed Central

Atomic force microscopy (AFM) is a technique used routinely in material science to image substances at a submicron (including nm) scale. We apply this technique to analysis of the fine structure of organic-walled Precambrian fossils, microscopic sphaeromorph acritarchs (cysts of planktonic unicellular protists) permineralized in ?650-million-year-old cherts of the Chichkan Formation of southern Kazakhstan. AFM images, backed by laser-Raman spectroscopic analysis of individual specimens, demonstrate that the walls of these petrified fossils are composed of stacked arrays of ?200-nm-sized angular platelets of polycyclic aromatic kerogen. Together, AFM and laser-Raman spectroscopy provide means by which to elucidate the submicron-scale structure of individual microscopic fossils, investigate the geochemical maturation of ancient organic matter, and, potentially, distinguish true fossils from pseudofossils and probe the mechanisms of fossil preservation by silica permineralization.

Kempe, Andre; Schopf, J. William; Altermann, Wladyslaw; Kudryavtsev, Anatoliy B.; Heckl, Wolfgang M.

2002-01-01

266

Fossil oak galls preserve ancient multitrophic interactions.  

PubMed

Trace fossils of insect feeding have contributed substantially to our understanding of the evolution of insect-plant interactions. The most complex phenotypes of herbivory are galls, whose diagnostic morphologies often allow the identification of the gall inducer. Although fossil insect-induced galls over 300Myr old are known, most are two-dimensional impressions lacking adequate morphological detail either for the precise identification of the causer or for detection of the communities of specialist parasitoids and inquilines inhabiting modern plant galls. Here, we describe the first evidence for such multitrophic associations in Pleistocene fossil galls from the Eemian interglacial (130000-115000 years ago) of The Netherlands. The exceptionally well-preserved fossils can be attributed to extant species of Andricus gallwasps (Hymenoptera: Cynipidae) galling oaks (Quercus), and provide the first fossil evidence of gall attack by herbivorous inquiline gallwasps. Furthermore, phylogenetic placement of one fossil in a lineage showing obligate host plant alternation implies the presence of a second oak species, Quercus cerris, currently unknown from Eemian fossils in northwestern Europe. This contrasts with the southern European native range of Q. cerris in the current interglacial and suggests that gallwasp invasions following human planting of Q. cerris in northern Europe may represent a return to preglacial distribution limits. PMID:18559323

Stone, Graham N; van der Ham, Raymond W J M; Brewer, Jan G

2008-10-01

267

Fossil oak galls preserve ancient multitrophic interactions  

PubMed Central

Trace fossils of insect feeding have contributed substantially to our understanding of the evolution of insect–plant interactions. The most complex phenotypes of herbivory are galls, whose diagnostic morphologies often allow the identification of the gall inducer. Although fossil insect-induced galls over 300?Myr old are known, most are two-dimensional impressions lacking adequate morphological detail either for the precise identification of the causer or for detection of the communities of specialist parasitoids and inquilines inhabiting modern plant galls. Here, we describe the first evidence for such multitrophic associations in Pleistocene fossil galls from the Eemian interglacial (130?000–115?000 years ago) of The Netherlands. The exceptionally well-preserved fossils can be attributed to extant species of Andricus gallwasps (Hymenoptera: Cynipidae) galling oaks (Quercus), and provide the first fossil evidence of gall attack by herbivorous inquiline gallwasps. Furthermore, phylogenetic placement of one fossil in a lineage showing obligate host plant alternation implies the presence of a second oak species, Quercus cerris, currently unknown from Eemian fossils in northwestern Europe. This contrasts with the southern European native range of Q. cerris in the current interglacial and suggests that gallwasp invasions following human planting of Q. cerris in northern Europe may represent a return to preglacial distribution limits.

Stone, Graham N; van der Ham, Raymond W.J.M; Brewer, Jan G

2008-01-01

268

Summary statistics for fossil spider species taxonomy  

PubMed Central

Abstract Spiders (Araneae) are one of the most species-rich orders on Earth today, and also have one of the longest geological records of any terrestrial animal groups, as demonstrated by their extensive fossil record. There are currently around 1150 described fossil spider species, representing 2.6% of all described spiders (i.e. extinct and extant). Data for numbers of fossil and living spider taxa described annually (and various other metrics for the fossil taxa) were compiled from current taxonomic catalogues. Data for extant taxa showed a steady linear increase of approximately 500 new species per year over the last decade, reflecting a rather constant research activity in this area by a large number of scientists, which can be expected to continue. The results for fossil species were very different, with peaks of new species descriptions followed by long troughs, indicating minimal new published research activity for most years. This pattern is indicative of short bursts of research by a limited number of authors. Given the frequent discovery of new fossil deposits containing spiders, a wealth of new material coming to light from previously worked deposits, and the application of new imaging techniques in palaeoarachnology that allow us to extract additional data from historical specimens, e.g. X-ray computed tomography, it is important not only to ensure a sustained research activity on fossil spiders (and other arachnids) through training and enthusing the next generation of palaeoarachnologists, but preferably to promote increased research and expertise in this field.

Penney, David; Dunlop, Jason A.; Marusik, Yuri M.

2012-01-01

269

Electrostatic considerations affecting the calculated HOMO-LUMO gap in protein molecules.  

PubMed

A detailed study of energy differences between the highest occupied and lowest unoccupied molecular orbitals (HOMO-LUMO gaps) in protein systems and water clusters is presented. Recent work questioning the applicability of Kohn-Sham density-functional theory to proteins and large water clusters (Rudberg 2012 J. Phys.: Condens. Matter 24 072202) has demonstrated vanishing HOMO-LUMO gaps for these systems, which is generally attributed to the treatment of exchange in the functional used. The present work shows that the vanishing gap is, in fact, an electrostatic artefact of the method used to prepare the system. Practical solutions for ensuring the gap is maintained when the system size is increased are demonstrated. This work has important implications for the use of large-scale density-functional theory in biomolecular systems, particularly in the simulation of photoemission, optical absorption and electronic transport, all of which depend critically on differences between energies of molecular orbitals. PMID:23470878

Lever, Greg; Cole, Daniel J; Hine, Nicholas D M; Haynes, Peter D; Payne, Mike C

2013-04-17

270

HOMO band dispersion of crystalline rubrene: Effects of self-energy corrections within the GW approximation  

NASA Astrophysics Data System (ADS)

We investigate the band dispersion and relevant electronic properties of rubrene single crystals within the GW approximation. Due to the self-energy correction, the dispersion of the highest occupied molecular orbital (HOMO) band increases by 0.10 eV compared to the dispersion of the Kohn-Sham eigenvalues within the generalized gradient approximation, and the effective hole mass consequently decreases. The resulting value of 0.90 times the electron rest mass along the ?-Y direction in the Brillouin zone is closer to experimental measurements than that obtained from density-functional theory. The enhanced bandwidth is explained in terms of the intermolecular hybridization of the HOMO(Y) wave function along the stacking direction of the molecules. Overall, our results support the bandlike interpretation of charge-carrier transport in rubrene.

Yanagisawa, Susumu; Morikawa, Yoshitada; Schindlmayr, Arno

2013-09-01

271

Electrostatic considerations affecting the calculated HOMO-LUMO gap in protein molecules  

NASA Astrophysics Data System (ADS)

A detailed study of energy differences between the highest occupied and lowest unoccupied molecular orbitals (HOMO-LUMO gaps) in protein systems and water clusters is presented. Recent work questioning the applicability of Kohn-Sham density-functional theory to proteins and large water clusters (Rudberg 2012 J. Phys.: Condens. Matter 24 072202) has demonstrated vanishing HOMO-LUMO gaps for these systems, which is generally attributed to the treatment of exchange in the functional used. The present work shows that the vanishing gap is, in fact, an electrostatic artefact of the method used to prepare the system. Practical solutions for ensuring the gap is maintained when the system size is increased are demonstrated. This work has important implications for the use of large-scale density-functional theory in biomolecular systems, particularly in the simulation of photoemission, optical absorption and electronic transport, all of which depend critically on differences between energies of molecular orbitals.

Lever, Greg; Cole, Daniel J.; Hine, Nicholas D. M.; Haynes, Peter D.; Payne, Mike C.

2013-04-01

272

Solid-state characterization and photoinduced intramolecular electron transfer in a nanoconfined octacationic homo[2]catenane.  

PubMed

An octacationic homo[2]catenane comprised of two mechanically interlocked cyclobis(paraquat-p-phenylene) rings has been obtained from the oxidation of the septacationic monoradical with nitrosonium hexafluoroantimonate. The nanoconfinement of normally repulsive bipyridinium units results in the enforced ?-overlap of eight positively charged pyridinium rings in a volume of <1.25 nm(3). In the solid state, the torsional angles around the C-C bonds between the four pairs of pyridinium rings range between 16 and 30°, while the ?-? stacking distances between the bipyridinium units are extended for the inside pair and contracted for the pairs on the outside-a consequence of Coulombic repulsion between the inner bipyridinium subunits. In solution, irradiation of the [2]catenane at 275 nm results in electron transfer from one of the paraphenylene rings to the inner bipyridinium dimer, leading to the generation of a temporary mixed-valence state within the rigid and robust homo[2]catenane. PMID:25010450

Barnes, Jonathan C; Frasconi, Marco; Young, Ryan M; Khdary, Nezar H; Liu, Wei-Guang; Dyar, Scott M; McGonigal, Paul R; Gibbs-Hall, Ian C; Diercks, Christian S; Sarjeant, Amy A; Stern, Charlotte L; Goddard, William A; Wasielewski, Michael R; Stoddart, J Fraser

2014-07-30

273

Polymerization or cyclic dimerization: solvent dependent homo-coupling of terminal alkynes at HOPG surface.  

PubMed

Surface reactivity has become one of the most important issues in surface chemistry over the past few years. In this work, we, for the first time, have investigated the homo-coupling of a special terminal alkyne derivative on the highly oriented pyrolitic graphite (HOPG) surface. Using scanning tunneling microscopy (STM) technique, we have found that such coupling reaction seriously depends on the supramolecular assembly of the monomer on the studied substrate, whereas the latter appears an obvious solvent effect. As a result, the reaction in our system undergoes polymerization and cyclic dimerization process in 1-phenyloctane and 1,2,4-trichlorobenzene, respectively. That is to say, the solvent effect can be extended from the two-dimensional (2D) supramolecular self-assembly to surface chemical reactions, and the selective homo-coupling has been successfully achieved at the solid/liquid interface. PMID:24469357

Zhang, Xuemei; Liao, Lingyan; Wang, Shuai; Hu, Fangyun; Wang, Chen; Zeng, Qingdao

2014-01-01

274

Tracking Ecological Change in Relation to the Emergence of Homo Near the Plio-Pleistocene Boundary  

Microsoft Academic Search

The emergence of species included in the genus Homo at ~2.4 Ma, as well as appearances of other hominin taxa between 3.0 and 1.8 Ma have often been attributed to global climate\\u000a change (deMenocal, 1995; deMenocal and Bloemendal, 1995; Vrba, 1995), but the precise details of these climatic transitions,\\u000a including causal factors, are still debated. In addition, the Plio-Pleistocene boundary

Kaye E. Reed; Samantha M. Russak

275

Late Pliocene Homo and Hominid Land Use from Western Olduvai Gorge, Tanzania  

Microsoft Academic Search

Excavation in the previously little-explored western portion of Olduvai Gorge indicates that hominid land use of the eastern paleobasin extended at least episodically to the west. Finds included a dentally complete Homo maxilla (OH 65) with lower face, Oldowan stone artifacts, and butchery-marked bones dated to be between 1.84 and 1.79 million years old. The hominid shows strong affinities to

Robert J. Blumenschine; Charles R. Peters; Fidelis T. Masao; Ronald J. Clarke; Alan L. Deino; Richard L. Hay; Carl C. Swisher; Ian G. Stanistreet; Gail M. Ashley; Lindsay J. McHenry; Nancy E. Sikes; Nikolaas J. van der Merwe; Joanne C. Tactikos; Amy E. Cushing; Daniel M. Deocampo; Jackson K. Njau; James I. Ebert

2003-01-01

276

Implicit and Explicit Category Learning by Macaques (Macaca mulatta) and Humans (Homo sapiens)  

Microsoft Academic Search

An influential theoretical perspective differentiates in humans an explicit, rule-based system of category learning from an implicit system that slowly associates different regions of perceptual space with different response outputs. This perspective was extended for the 1st time to the category learning of nonhuman primates. Humans (Homo sapiens) and macaques (Macaca mulatta) learned categories composed of sine-wave gratings that varied

J. David Smith; Michael J. Beran; Matthew J. Crossley; Joseph Boomer; F. Gregory Ashby

2010-01-01

277

Hegemonie, Identität und der homo oeconomicus Oder: Warum feministische Ökonomie nicht ausreicht  

Microsoft Academic Search

\\u000a Während dieser Artikel entsteht, laufen die Präsidentschaftswahlen in den USA. Barack Obama wird gewählt, Bundeskanzlerin\\u000a Angela Merkel schickt eine Grußbotschaft – das Geschlecht oder die Hautfarbe scheinen heute in keinem Widerspruch zur Karriere\\u000a mehr zu stehen. Das Bild des homo oeconomicus, dem Subjekt in der Wirtschaftstheorie – jung, dynamisch, gesund, unabhängig, erfolgreich etc. – gilt heute auch für Frauen\\u000a und

Friederike Habermann

278

Multiplex Detection of Homo- and Heterodimerization of G Protein-Coupled Receptors by Proximity Biotinylation  

PubMed Central

Dimerization of G protein-coupled receptors (GPCRs) represents a potential mechanism by which GPCR functions are regulated. Several resonance energy transfer (RET)-based methods have revealed GPCR homo- and heterodimerization. However, interpretation of an increase in FRET efficiency could be attributed to either dimerization/oligomerization events or conformational changes within an already dimerized/oligomerized receptor complex. Furthermore, RET-based methods can only measure pairwise dimerization, and cannot easily achieve multiplex detection. In this study, we applied proximity-based biotinylation for detecting receptor dimerization by utilizing a specific enzyme-substrate pair that are fused to GPCRs. The biotin ligase BirA is fused to CXCR4 and site-specifically biotinylates an acceptor peptide (AP) in the presence of biotin. As a test case for our newly developed assay, we have characterized the homo-dimerization of chemokine receptor CXCR4 and heterodimerization of CXCR4 with CCR2 or CCR5. The degree of biotinylation varies with the amount of GPCR-AP as well as biotinylation time. Using enzyme/substrate receptor pairs and measuring receptor biotinylation, we demonstrate that CXCR4 can homo-dimerize and hetero-dimerize with CCR2 and CCR5. The effect of CXCL12, agonist for CXCR4, was found to decrease surface biotinylation of CXCR4-AP. This effect is due to a combination of CXCR4 endocytosis and stabilization of CXCR4 homodimers. Finally, when CXCR4-AP, CCR2-AP, and CCR5-AP were expressed together, we observed CXCR4-CXCR4 homodimers and CXCR4-CCR2 and CXCR4-CCR5 heterodimers. The newly developed assay opens new opportunity for multiplex detection for GPCR homo- and heterodimerization within the same cellular context.

Liu, Allen P.

2014-01-01

279

HomoSAR: bridging comparative protein modeling with quantitative structural activity relationship to design new peptides.  

PubMed

Peptides play significant roles in the biological world. To optimize activity for a specific therapeutic target, peptide library synthesis is inevitable; which is a time consuming and expensive. Computational approaches provide a promising way to simply elucidate the structural basis in the design of new peptides. Earlier, we proposed a novel methodology termed HomoSAR to gain insight into the structure activity relationships underlying peptides. Based on an integrated approach, HomoSAR uses the principles of homology modeling in conjunction with the quantitative structural activity relationship formalism to predict and design new peptide sequences with the optimum activity. In the present study, we establish that the HomoSAR methodology can be universally applied to all classes of peptides irrespective of sequence length by studying HomoSAR on three peptide datasets viz., angiotensin-converting enzyme inhibitory peptides, CAMEL-s antibiotic peptides, and hAmphiphysin-1 SH3 domain binding peptides, using a set of descriptors related to the hydrophobic, steric, and electronic properties of the 20 natural amino acids. Models generated for all three datasets have statistically significant correlation coefficients (r(2)) and predictive r2 (r(pred)2) and cross validated coefficient ( q(LOO)2). The daintiness of this technique lies in its simplicity and ability to extract all the information contained in the peptides to elucidate the underlying structure activity relationships. The difficulties of correlating both sequence diversity and variation in length of the peptides with their biological activity can be addressed. The study has been able to identify the preferred or detrimental nature of amino acids at specific positions in the peptide sequences. PMID:24105965

Borkar, Mahesh R; Pissurlenkar, Raghuvir R S; Coutinho, Evans C

2013-11-15

280

Silicone waxes—synthesis via hydrosilylation in homo- and heterogeneous systems  

Microsoft Academic Search

Silicone waxes, i.e. polysiloxanes with a long alkyl chain (>C8) as a pendant group make one of the most important classes of modified polysiloxanes widely applied to many branches of industry. Main methods of synthesis of silicone waxes are based on catalytic processes of hydrosilylation of alkenes with poly(hydro, methyl)siloxanes. Results of studies on syntheses of silicone waxes in homo-

Hieronim Maciejewski; Agata Wawrzy?czak; Micha? Dutkiewicz; Ryszard Fiedorow

2006-01-01

281

Carabelli's trait revisited: an examination of mesiolingual features at the enamel-dentine junction and enamel surface of Pan and Homo sapiens upper molars.  

PubMed

Carabelli's trait is a morphological feature that frequently occurs on the mesiolingual aspect of Homo sapiens upper molars. Similar structures also referred to as Carabelli's trait have been reported in apes and fossil hominins. However, the morphological development and homology of these mesiolingual structures among hominoids are poorly understood. In this study, we employ micro-computed tomography to image the enamel-dentine junction (EDJ) and outer enamel surface (OES) of Pan (n = 48) and H. sapiens (n = 52) upper molars. We investigate the developmental origin of mesiolingual features in these taxa and establish the relative contribution of the EDJ and enamel cap to feature expression. Results demonstrate that mesiolingual features of H. sapiens molars develop at the EDJ and are similarly expressed at the OES. Morphological variation at both surfaces in this taxon can satisfactorily be assessed using standards for Carabelli's trait developed by the Arizona State University Dental Anthropology System (ASUDAS). Relative to H. sapiens, Pan has an even greater degree of correspondence in feature expression between the EDJ and OES. Morphological manifestations in Pan molars are not necessarily limited to the protocone and are best characterized by a lingual cingulum that cannot be captured by the ASUDAS. Cusp-like structures, similar to those seen in marked Carabelli's trait expressions in H. sapiens, were not found in Pan. This study provides a foundation for further analyses on the evolutionary history of mesiolingual dental traits within the hominoid lineage. It also highlights the wealth of morphological data that can be obtained at the EDJ for understanding tooth development and for characterizing tooth crown variation in worn fossil teeth. PMID:22889682

Ortiz, Alejandra; Skinner, Matthew M; Bailey, Shara E; Hublin, Jean-Jacques

2012-10-01

282

On the trail of the genus Homo between archaic and derived morphologies.  

PubMed

The topic of this review is the evolution of the genus Homo, focusing on evolutionary transitions that occurred during the Early and Middle Pleistocene. Two crucial issues are addressed in particular: 1) the emergence in the Early Pleistocene of the archaic variant of Homo that might represent the last common ancestor before the emergence of at least two (more probably three) geographically distinct trajectories; and (2) the evolution of these derived lineages, ultimately leading to the allopatric speciations of the most encephalised species of Homo: H. neanderthalensis and H. sapiens. In this framework, the time window between 1.0 million years ago (Ma) and 500 thousand years ago (ka) is of crucial importance, since it is probable that a new kind of humanity emerged in this period and then spread across a wide area encompassing Africa and Eurasia. These humans are represented by a number of specimens that are included within the single, polymorphic, and widespread species H. heidelbergensis. It is suggested that, in the course of the Middle Pleistocene, this species diversified in a number of incipient species -or subspecies- geographically and phenotypically distinct from one another. The case-study furnished by the calvarium found near Ceprano, in Italy, is of great interest in this regard, since it displays the least derived morphology seen among the hypodigm of H. heidelbergensis, and may represent better than other specimens the ancestral morphotype (i.e., the stem subspecies) of this taxon. PMID:23274748

Manzi, Giorgio

2012-01-01

283

Spitzer Digs Up Galactic Fossil  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site] Figure 1

[figure removed for brevity, see original site] Figure 2

This false-color image taken by NASA's Spitzer Space Telescope shows a globular cluster previously hidden in the dusty plane of our Milky Way galaxy. Globular clusters are compact bundles of old stars that date back to the birth of our galaxy, 13 or so billion years ago. Astronomers use these galactic 'fossils' as tools for studying the age and formation of the Milky Way.

Most clusters orbit around the center of the galaxy well above its dust-enshrouded disc, or plane, while making brief, repeated passes through the plane that each last about a million years. Spitzer, with infrared eyes that can see into the dusty galactic plane, first spotted the newfound cluster during its current pass. A visible-light image (inset of Figure 1) shows only a dark patch of sky.

The red streak behind the core of the cluster is a dust cloud, which may indicate the cluster's interaction with the Milky Way. Alternatively, this cloud may lie coincidentally along Spitzer's line of sight.

Follow-up observations with the University of Wyoming Infrared Observatory helped set the distance of the new cluster at about 9,000 light-years from Earth - closer than most clusters - and set the mass at the equivalent of 300,000 Suns. The cluster's apparent size, as viewed from Earth, is comparable to a grain of rice held at arm's length. It is located in the constellation Aquila.

Astronomers believe that this cluster may be one of the last in our galaxy to be uncovered.

This image composite was taken on April 21, 2004, by Spitzer's infrared array camera. It is composed of images obtained at four wavelengths: 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange) and 8 microns (red).

Galactic Fossil Found Behind Curtain of Dust In Figure 2, the image mosaic shows the same patch of sky in various wavelengths of light. While the visible-light image (left) shows a dark sky speckled with stars, infrared images (middle and right), reveal a never-before-seen bundle of stars, called a globular cluster. The left panel is from the California Institute of Technology's Digitized Sky Survey; the middle panel includes images from the NASA-funded Two Micron All-Sky Survey and the University of Wyoming Infrared Observatory (circle inset); and the right panel is from NASA's Spitzer Space Telescope.

The Two Micron All-Sky Survey false-color image was obtained using near-infrared wavelengths ranging from 1.3 to 2.2 microns. The University of Wyoming Observatory false-color image was captured on July 31, 2004, at wavelengths ranging from 1.2 to 2.2 microns. The Spitzer false-color image composite was taken on April 21, 2004, by its infrared array camera. It is composed of images obtained at four mid-infrared wavelengths: 3.6 microns (blue), 4.5 microns (green), 5.8 microns (orange) and 8 microns (red).

2004-01-01

284

How a Dinosaur Became a Fossil  

NSDL National Science Digital Library

This interactive resource adapted from the Museum of Paleontology at the University of California, Berkeley shows how a dinosaur can be buried under sediment after it dies, become a fossil, and then become exposed and discovered by paleontologists.

Foundation, Wgbh E.

2005-12-17

285

New Technologies in Fossil-Fuel Utilization.  

National Technical Information Service (NTIS)

This document contains the outline and viewgraphs used in the speech. Topics covered are: conventional oil and gas recovery; unconventional oil and gas sources; oil shale resources; conventional coal combustion; advanced fossil power systems; fluidized be...

H. D. Cochran

1982-01-01

286

Fossil energy program. Progress report, July 1980  

SciTech Connect

This report - the seventy-second of a series - is a compendium of monthly progress reports for the ORNL research and development programs that are in support of the increased utilization of coal and other fossil fuel alternatives to oil and gas as sources of clean energy. The projects reported this month include those for coal conversion development, chemical research and development, materials technology, component development and process evaluation, technical support to major liquefaction projects, process and program analysis, fossil energy environmental analysis, coal preparation and waste utilization, coal preparation plant automation, atmospheric fluidized bed coal combustor for cogeneration, technical support to the TVA fluidized bed combustion demonstration plant program, fossil energy applications assessments, performance assurance system support for fossil energy projects, international assessment of atmospheric fluidized bed combustion technology, and PFBC systems analysis.

McNeese, L. E.

1980-10-01

287

Fossil Finds Expand Early Hominid Anatomy.  

ERIC Educational Resources Information Center

Hominid fossils found in late 1990 in Ethiopia are reported. A controversy surrounding these remains and those of earlier expeditions, including Lucy, over whether more than one species of hominid are represented is discussed. (CW)

Bower, B.

1991-01-01

288

Homo sapiens (Cro-magnon and modern human), Chris StringerSite: DNA Interactive (www.dnai.org)  

NSDL National Science Digital Library

Interviewee: Chris Stringer DNAi Location:Applications>Human origins>our family tree>Modern humans: a late arrival Human origins expert Chris Stringer talks about the arrival of Homo sapiens and our possible ancestors.

2008-10-06

289

"Homo High"  

ERIC Educational Resources Information Center

In Chicago's public school system, LGBT students were three times more likely than straight peers to miss school because of threats to their safety, according to 2003 districtwide survey; and students who face regular harassment were more like to drop out. In this article, the author shares her thoughts on the move of Chicago school officials to…

Kilman, Carrie

2010-01-01

290

Method of burning a fossil fuel  

Microsoft Academic Search

A method is disclosed for burning a fossil fuel and air with the emmission of an exhaust gas consisting essentially of atmospheric gases, carbon dioxide and water vapor and essentially free of carbon monoxide, hydrocarbons and nitric oxide, which comprises burning the fossil fuel at a temperature between 1000°C and 1500°C with less than the stoichiometric amount of atmospheric oxygen

Whelan

1978-01-01

291

Quantifying Fossil Fuel CO 2 over Europe  

Microsoft Academic Search

Europe is responsible for more than 25% of global fossil fuel CO2 emissions (Marland et al. 2006), and these emissions account for about 30–50% of the observed CO2 variability in this region (see Sect. 4.2.1). To balance greenhouse gases over Europe, therefore, also requires quantification\\u000a of CO2 emissions from fossil fuel (i.e. coal, oil and natural gas) burning. Reliable continuous

Ingeborg Levin; Ute Karstens

292

Fullerenes in the Fossil of Dinosaur Egg  

Microsoft Academic Search

By means of laser desorption post-ionization time-of flight mass specrometry (TOF) and high-pressure liquid chromatography (HPLC), fullerene C60 have been found in a fossil of dinosaur egg shell from Xixia (N33.3 E111.4), China. These techniques verified also mat fullerene C70 is virtually absent from identical egg fossil of dinosaur at XiXia. Preliminary results suggest that C60 occurrence and C70 absence

Wang Zhenxia; Li Xuepeng; Wang Wenmin; Xu Xunjiang; Zi Chao Tang; Rong-Bin Huang; Lan-Sun Zheng

1998-01-01

293

Species in the primate fossil record.  

PubMed

Species in the fossil record are population pools of genetic and phenetic variation at a place and time, morphologically recognizable and distinguishable from others by empirical standards. Change through time can be substantial, requiring subdivision of lineages that becomes more arbitrary as they become more complete. Evolution is about form, space, and time; it is about variation and change. Interpretation of species in the fossil record touches all of these. PMID:24591141

Gingerich, Philip D

2014-01-01

294

Fossil group origins. IV. Characterization of the sample and observational properties of fossil systems  

NASA Astrophysics Data System (ADS)

Context. Virialized halos grow by the accretion of smaller ones in the cold dark matter scenario. The rate of accretion depends on the different properties of the host halo. Those halos for which this accretion rate was very fast and efficient resulted in systems dominated by a central galaxy surrounded by smaller galaxies that were at least two magnitudes fainter. These galaxy systems are called fossil systems, and they can be the fossil relics of ancient galaxy structures. Aims: We started an extensive observational program to characterize a sample of 34 fossil group candidates spanning a broad range of physical properties. Methods: Deep r-band images were obtained with the 2.5-m Isaac Newton Telescope and Nordic Optic Telescope. Optical spectroscopic observations were performed at the 3.5-m Telescopio Nazionale Galileo for ~1200 galaxies. This new dataset was completed with Sloan Digital Sky Survey Data Release 7 archival data to obtain robust cluster membership and global properties of each fossil group candidate. For each system, we recomputed the magnitude gaps between the two brightest galaxies (?m12) and the first and fourth ranked galaxies (?m14) within 0.5 R200. We consider fossil systems to be those with ?m12 ? 2 mag or ?m14 ? 2.5 mag within the errors. Results: We find that 15 candidates turned out to be fossil systems. Their observational properties agree with those of non-fossil systems. Both follow the same correlations, but the fossil systems are always extreme cases. In particular, they host the brightest central galaxies, and the fraction of total galaxy light enclosed in the brightest group galaxy is larger in fossil than in non-fossil systems. Finally, we confirm the existence of genuine fossil clusters. Conclusions: Combining our results with others in the literature, we favor the merging scenario in which fossil systems formed from mergers of L? galaxies. The large magnitude gap is a consequence of the extreme merger ratio within fossil systems and therefore it is an evolutionary effect. Moreover, we suggest that at least one fossil group candidate in our sample could represent a transitional fossil stage. This system could have been a fossil in the past, but not now owing to the recent accretion of another group of galaxies.

Zarattini, S.; Barrena, R.; Girardi, M.; Castro-Rodriguez, N.; Boschin, W.; Aguerri, J. A. L.; Méndez-Abreu, J.; Sánchez-Janssen, R.; Catalán-Torrecilla, C.; Corsini, E. M.; del Burgo, C.; D'Onghia, E.; Herrera-Ruiz, N.; Iglesias-Páramo, J.; Jimenez Bailon, E.; Lozada Muoz, M.; Napolitano, N.; Vilchez, J. M.

2014-05-01

295

Functional consequences of homo- but not hetero-oligomerization between transporters for the biogenic amine neurotransmitters  

PubMed Central

Before this study, the human norepinephrine transporter (hNET) was the only member of the biogenic amine neurotransmitter transporter family that had not been demonstrated to be a functional homo-oligomer. Here, using two forms of the transporter, I155C and hNET-myc, with distinct antigenicity and inhibitor sensitivity, we demonstrated that hNET exists as a homo-oligomer. hNET I155C is a functional mutant and is sensitive to inactivation by the sulfhydryl reagent [2-(trimethylammonium)ethyl]methanethiosulfonate, while hNET-myc is resistant to inactivation by this reagent. Coimmunoprecipitation of these two forms demonstrated that a physical interaction exists between norepinephrine transporter monomers. Further characterization of this physical interaction has revealed that the activity of norepinephrine transporters depends on interactions between monomers. Because norepinephrine transporters and serotonin transporters are the only two members of the neurotransmitter transporter family endogenously expressed in the cell membrane of the same cells, placental syncytiotrophoblasts, we tested the ability of norepinephrine transporters and serotonin transporters to associate and function in a hetero-oligomeric form. Similarly, coexpression of hNET-myc with serotonin transporter-FLAG showed a physical interaction in coimmunoprecipitation assays. However, coexpression of serotonin and norepinephrine transporters did not sensitize norepinephrine transporter activity to inhibition by citalopram, a selective serotonin transport inhibitor. Thus, the norepinephrine transporter–serotonin transporter physical association did not produce functional consequences. Based on this, we propose that the transporters for biogenic amine neurotransmitters interact functionally in homo- but not hetero-oligomeric forms.

Kocabas, A. M.; Rudnick, G.; Kilic, F.

2011-01-01

296

Kinin B1 receptor homo-oligomerization is required for receptor trafficking to the cell surface.  

PubMed

The kinin B1 receptor (B1R) is a G protein-coupled receptor with pro-inflammatory activity that is latent in healthy tissues but induced by tissue insult. Here, we investigated if B1R homo-oligomerization is a possible mechanism regulating the presentation of this receptor at the level of maturation and trafficking to the cell surface. To this end, we used HEK293 cells stably expressing N-terminal FLAG and HA epitope-tagged wild-type human B1R and an N-terminal receptor fragment, B1stop135, which terminates at the C-terminal end of the third transmembrane domain and has previously been shown to oligomerize with B1R. Receptors were monitored by immunoblotting and immunoprecipitation, receptor function by agonist binding and agonist-promoted phosphoinositide hydrolysis, and receptor trafficking by confocal immunofluorescence microscopy. When expressed alone, B1R is core N-glycosylated and forms oligomers localized intracellularly and on the cell surface. B1stop135 also exists as core N-glycosylated oligomers but is localized exclusively intracellularly. When co-expressed, B1stop135 prevents specifically B1R homo-oligomerization by forming nonfunctional B1R-B1stop135 hetero-oligomers, retains B1R intracellularly at least in part in the endoplasmatic reticulum (ER), increases calnexin binding to the receptor, and increases receptor degradation. We conclude that B1R homo-oligomerization is necessary for B1R maturation and trafficking to the cell surface. Modulating this mechanism may be a novel therapeutic avenue in inflammatory disease. PMID:23201435

Sandén, Caroline; Leeb-Lundberg, L M Fredrik

2013-01-01

297

Asymmetric phase-transfer catalysis with homo- and heterochiral quaternary ammonium salts: a theoretical study.  

PubMed

A thorough theoretical study of phase-transfer quaternary ammonium catalysts designed by the Maruoka group has been performed in an attempt to gain better understanding of the properties and catalytic behavior of the homo- and heterochiral forms of these systems. The conformationally flexible analogue is found to easily undergo interconversion from the homo- to the heterochiral form driven by the higher thermodynamic stability of the heterochiral isomer and resulting in alternation in catalytic behavior. Theoretical calculations of (1)H NMR spectra of the two isomers for different model systems are in good agreement with the experimental data, allowing us to conclude that the upfield shift of signals for the benzylic protons in the heterochiral form could be explained by an increase in the shielding effect of the aromatic parts of the system around these protons due to the conformational changes. By applying the automated transition state (TS) search procedure for the alkylation of glycine derivatives catalyzed by the homo-/heterochiral form of a conformationally rigid analogue, we were able to locate more than 40 configurations of the TS structures. In brief, the homochiral form was theoretically confirmed to catalyze the formation of the predominant R-product, while for the heterochiral form the catalytic activity is found to depend on two factors: (i) formation of a tight ion pair between the catalyst and the glycine derivative, which results in a decrease in the reaction rate, in agreement with the experimental data, and formation of only the R-product, and (ii) the possibility that the reaction occurs without the initial formation of the ion pair or after its dissociation, in which case the formation of an S-product is predominant. The combined effects of both factors would explain the lower reaction rate and the poor enantioselectivity observed experimentally for the heterochiral form. PMID:24720781

Petrova, Galina P; Li, Hai-Bei; Maruoka, Keiji; Morokuma, Keiji

2014-05-15

298

The problems and potential of using animal fossils and trace fossils in terminal Proterozoic biostratigraphy  

Microsoft Academic Search

Despite the discovery of soft-bodied megascopic fossils of late Neoproterozoic age at numerous localities world-wide, there has been slow acceptance of their potential for intercontinental correlation. The stratigraphic thickness of sediments separating individual occurrences of such fossils from the base of the Cambrian is very varied. Basic questions have also been posed as to the classification of the organisms represented

Richard J. F. Jenkins

1995-01-01

299

Pygmoid Australomelanesian Homo sapiens skeletal remains from Liang Bua, Flores: Population affinities and pathological abnormalities  

PubMed Central

Liang Bua 1 (LB1) exhibits marked craniofacial and postcranial asymmetries and other indicators of abnormal growth and development. Anomalies aside, 140 cranial features place LB1 within modern human ranges of variation, resembling Australomelanesian populations. Mandibular and dental features of LB1 and LB6/1 either show no substantial deviation from modern Homo sapiens or share features (receding chins and rotated premolars) with Rampasasa pygmies now living near Liang Bua Cave. We propose that LB1 is drawn from an earlier pygmy H. sapiens population but individually shows signs of a developmental abnormality, including microcephaly. Additional mandibular and postcranial remains from the site share small body size but not microcephaly.

Jacob, T.; Indriati, E.; Soejono, R. P.; Hsu, K.; Frayer, D. W.; Eckhardt, R. B.; Kuperavage, A. J.; Thorne, A.; Henneberg, M.

2006-01-01

300

Tuning of HOMO levels of carbazole derivatives: New molecules for blue OLED  

Microsoft Academic Search

The Suzuki–Miyaura coupling between 3,6-dibromo-N-hexylcarbazole and aryl-boronic acids catalyzed by Pd(PPh3)4 afforded blue emitting molecules, 3,6-diaryl-N-hexylcarbazole: aryl=phenyl (1), p-methoxyphenyl (2), p-cyanophenyl (3), p-acetophenyl (4), pyrenyl (5), biphenyl (6), difluorophenyl (7) and p-nitrophenyl (8), in good yield. The HOMO level of the carbazole derivative varied between ?5.67 and ?6.02eV due to the electron-withdrawing or donating substituent in the aryl group. This

Neeraj Agarwal; Pabitra K. Nayak; Farman Ali; Meghan P. Patankar; K. L. Narasimhan; N. Periasamy

2011-01-01

301

Mineralogy of fossil resins in Northern Eurasia  

NASA Astrophysics Data System (ADS)

The investigation is focused on identification and origin of fossil resins from the Cretaceous, Tertiary, and Quaternary sediments of Northern Eurasia on the basis of detailed study of their physical and chemical characteristics: morphology; size; mass; density; optical, mechanical, and thermal properties; chemical composition; etc. The composition of amorphous organic minerals with polymeric structure, fossil resins included, is studied with IR spectrometry, the EPR method, derivatography at low heating rates, XRD, chemical analysis, emission spectrometry, etc. The results of investigation summarized for the Baltic-Dnieper, North Siberian, and Far East amber-bearing provinces show some similarity of fossil resins in combination with specific features inherent to each province. Resins from the Baltic-Dnieper province should be termed as amber (succinite). Their variety is the most characteristic of Northern and Eastern Europe. Amber-like fossil resins from the North Siberian and Far East provinces are irrelevant to succinite. They usually occur as brittle resins, namely, retinite and gedanite, without jewelry value. Viscous fossil resin rumänite with an expected high economic value occurs in the Far East, on the shore of Sakhalin Island.

Bogdasarov, M. A.

2007-12-01

302

Body size and its consequences: allometry and the lower limb length of Liang Bua 1 (Homo floresiensis).  

PubMed

Bivariate femoral length allometry in recent humans, Pan, and Gorilla is investigated with special reference to the diminutive Liang Bua (LB) 1 specimen (the holotype of Homo floresiensis) and six early Pleistocene femora referred to the genus Homo. Relative to predicted body mass, Pan and Gorilla femora show strong negative length allometry while recent human femora evince isometry to positive allometry, depending on sample composition and line-fitting technique employed. The allometric trajectories of Pan and Homo show convergence near the small body size range of LB 1, such that LB 1 manifests a low percentage deviation (d(yx) of Smith [1980]) from the Pan allometric trajectory and falls well within the 95% confidence limits around the Pan individuals (but also outside the 95% confidence limits for recent Homo). In contrast, the six early Pleistocene Homo femora, belonging to larger individuals, show much greater d(yx) values from both Pan and Gorilla and fall well above the 95% confidence limits for these taxa. All but one of these Pleistocene Homo specimens falls within the 95% confidence limits of the recent human sample. Similar results are obtained when femoral length is regressed on femoral head diameter in unlogged bivariate space. Regardless of the ultimate taxonomic status of LB 1, these findings are consistent with a prediction made by us (Franciscus and Holliday, 1992) that hominins in the small body size range of A.L. 288-1 ("Lucy"), including members of the genus Homo, will tend to possess short, ape-like lower limbs as a function of body size scaling. PMID:19674770

Holliday, Trenton W; Franciscus, Robert G

2009-09-01

303

Eumetazoan fossils in terminal Proterozoic phosphorites?  

PubMed Central

Phosphatic sedimentary rocks preserve a record of early animal life different from and complementary to that provided by Ediacaran fossils in terminal Proterozoic sandstones and shales. Phosphorites of the Doushantuo Formation, South China, contain eggs, egg cases, and stereoblastulae that document animals of unspecified phylogenetic position; small fossils containing putative spicules may specifically record the presence of sponges. Microfossils recently interpreted as the preserved gastrulae of cnidarian and bilaterian metazoans can alternatively be interpreted as conventional algal cysts and/or egg cases modified by diagenetic processes known to have had a pervasive influence on Doushantuo phosphorites. Regardless of this interpretation, evidence for Doushantuo eumetazoans is provided by millimeter-scale tubes that display tabulation and apical budding characteristic of some Cnidaria, especially the extinct tabulates. Like some Ediacaran remains, these small, benthic, colonial fossils may represent stem-group eumetazoans or stem-group cnidarians that lived in the late Proterozoic ocean.

Xiao, Shuhai; Yuan, Xunlai; Knoll, Andrew H.

2000-01-01

304

Recent synchronous radiation of a living fossil.  

PubMed

Modern survivors of previously more diverse lineages are regarded as living fossils, particularly when characterized by morphological stasis. Cycads are often cited as a classic example, reaching their greatest diversity during the Jurassic-Cretaceous (199.6 to 65.5 million years ago) then dwindling to their present diversity of ~300 species as flowering plants rose to dominance. Using fossil-calibrated molecular phylogenies, we show that cycads underwent a near synchronous global rediversification beginning in the late Miocene, followed by a slowdown toward the Recent. Although the cycad lineage is ancient, our timetrees indicate that living cycad species are not much older than ~12 million years. These data reject the hypothesized role of dinosaurs in generating extant diversity and the designation of today's cycad species as living fossils. PMID:22021670

Nagalingum, N S; Marshall, C R; Quental, T B; Rai, H S; Little, D P; Mathews, S

2011-11-11

305

Insect diversity in the fossil record.  

PubMed

Insects possess a surprisingly extensive fossil record. Compilation of the geochronologic ranges of insect families demonstrates that their diversity exceeds that of preserved vertebrate tetrapods through 91 percent of their evolutionary history. The great diversity of insects was achieved not by high origination rates but rather by low extinction rates comparable to the low rates of slowly evolving marine invertebrate groups. The great radiation of modern insects began 245 million years ago and was not accelerated by the expansion of angiosperms during the Cretaceous period. The basic trophic machinery of insects was in place nearly 100 million years before angiosperms appeared in the fossil record. PMID:11536548

Labandeira, C C; Sepkoski, J J

1993-07-16

306

Fossils: An Ancient Sea in Indiana  

NSDL National Science Digital Library

Paleontologists have been remarkably successful in determining what earlier life forms looked like, as well as how they probably behaved when alive. This interactive feature illustrates a slab of rock containing fossils of several types of creatures that once inhabited the Borden Sea, over 300 million years ago in what is now central Indiana. Clicking on highlighted fossils accesses animations of what they may have looked like in life, along with a brief description of the organism. Reconstructions such as these have given scientists insight into evolutionary processes and trends. A background essay and discussion questions are included.

2011-05-09

307

Brachiopod exercise for FossilPlot  

NSDL National Science Digital Library

Students are taught how to use FossilPlot software in the lab prior to this exercise. Students work individual to work through the short exercise, handing in a copy of the diversity graphs for the brachiopod orders (which will be tested in the following midterm) and a completed worksheet. The exercise reinforces the main functions of FossilPlot and addresses basic concepts on diversity and biostratigraphy. Once the assignments are collected and graded, we discuss the outcomes of the exercise in class.

Tapanila, Leif

308

Microbial Fossils Detected in Desert Varnish  

NASA Technical Reports Server (NTRS)

Mars Global Surveyor Thermal Emission Spectrometer data indicate regions with significant levels of hematite (_Fe2O3). Fe-oxides, like hematite, can form as aqueous mineral precipitates and as such may preserve microscopic fossils or other biosignatures. Several potential terrestrial analogues to martian hematite like hydrothermal vents have preserved microfossils. Microbial fossilization in Fe-oxides is often a function of biomineralization. For example, goethite (FeO2H) encrustation of fungal mycelia from the mid-Tertiary preserved fungal morphologies such that their genera could be determined.

Flood, B. E.; Allen, C.; Longazo, T.

2003-01-01

309

Initiation of the microgene polymerization reaction with non-repetitive homo-duplexes  

SciTech Connect

Microgene Polymerization Reaction (MPR) is used as an experimental system to artificially simulate evolution of short, non-repetitive homo-duplex DNA into multiply-repetitive products that can code for functional proteins. Blunt-end ligation by DNA polymerase is crucial in expansion of homo-duplexes (HDs) into head-to-tail multiple repeats in MPR. The propagation mechanism is known, but formation of the initial doublet (ID) by juxtaposing two HDs and polymerization through the gap has been ambiguous. Initiation events with pairs of HDs using Real-Time PCR were more frequent at higher HD concentrations and slightly below the melting temperature. A process molecularity of about 3.1, calculated from the amplification efficiency and the difference in PCR cycles at which propagation was detected at varying HD concentrations, led to a simple mechanism for ID formation: the gap between two HDs is bridged by a third. Considering thermodynamic aspects of the presumed intermediate 'nucleation complex' can predict relative propensity for the process with other HDs.

Itsko, Mark [Department of Life Sciences, Faculty of Natural Sciences, Ben-Gurion University of the Negev, PO Box 653, Be'er-Sheva 84105 (Israel)], E-mail: ariehz@bgu.ac.il; Zaritsky, Arieh [Department of Life Sciences, Faculty of Natural Sciences, Ben-Gurion University of the Negev, PO Box 653, Be'er-Sheva 84105 (Israel); Rabinovitch, Avinoam [Department of Physics, Faculty of Natural Sciences, Ben-Gurion University of the Negev, PO Box 653, Be'er-Sheva 84105 (Israel); Ben-Dov, Eitan [Department of Biotechnology Engineering, Faculty of Engineering Sciences, Ben-Gurion University of the Negev, PO Box 653, Be'er-Sheva 84105 (Israel); Achva Academic College, MP Shikmim, 79800 (Israel)

2008-04-11

310

Aggregation propensity of Aib homo-peptides of different length: an insight from molecular dynamics simulations.  

PubMed

Interactions between peptides are relevant from a biomedical point of view, in particular for the role played by their aggregates in different important pathologies, and also because peptide aggregates represent promising scaffolds for innovative materials. In the present article, the aggregation properties of the homo-peptides formed by ?-aminoisobutyric acid (U) residues are discussed. The peptides investigated have chain lengths between six and 15 residues and comprise benzyl and naphthyl groups at the N- and C-termini, respectively. Spectroscopic experiments and molecular dynamics simulations show that the shortest homo-peptide, constituted by six U, does not exhibit any tendency to aggregate under the conditions examined. On the other hand, the homologous peptide with 15 U forms very stable and compact aggregates in 70/30(v/v) methanol/water solution. Atomic force microscopy images indicate that these aggregates promote formation of long fibrils once they are deposited on a mica surface. The aggregation phenomenon is mainly due to hydrophobic interactions occurring between very stable helical structures, and the aromatic groups in the peptides seem to play a minor role. Copyright © 2014 European Peptide Society and John Wiley & Sons, Ltd. PMID:24845474

Bocchinfuso, Gianfranco; Conflitti, Paolo; Raniolo, Stefano; Caruso, Mario; Mazzuca, Claudia; Gatto, Emanuela; Placidi, Ernesto; Formaggio, Fernando; Toniolo, Claudio; Venanzi, Mariano; Palleschi, Antonio

2014-07-01

311

Tuning of the HOMO-LUMO gap of donor-substituted symmetrical and unsymmetrical benzothiadiazoles.  

PubMed

This article reports the design and synthesis of donor-substituted symmetrical and unsymmetrical benzothiadiazoles (BTDs) of type D-?-A-D, D1-?-A-D2, D1-A1-A2-D2, D-A1-A2-D and D-A1-A2-A1-D by Ullmann, Suzuki and cycloaddition-retroelectrocyclization reactions. The photophysical, electrochemical and computational properties were studied and show substantial donor-acceptor interaction. Their single photon absorption show strong charge transfer bands in the near-infrared (NIR) region and the electrochemical reduction show multiple reduction waves. The optical HOMO-LUMO gap of BTDs was found to be a function of the number and nature of the acceptors. Computational studies reveal that strong cyano-based acceptors, dicyanoquinodimethane (DCNQ) and tetracyanobutadiene (TCBD) lower the LUMO level in BTDs , which results in a low HOMO-LUMO gap compared to acetylene linked BTDs and . The BTDs with carbazole and single TCBD and DCNQ acceptors show better thermal stability. PMID:24940822

Misra, Rajneesh; Gautam, Prabhat

2014-07-01

312

Midsagittal cranial shape variation in the genus Homo by geometric morphometrics.  

PubMed

Midsagittal profiles of crania referred to different taxa of the genus Homo have been analyzed by geometric morphometric techniques. Comparisons between single specimens using the thin-plate-spline function suggest a generalized reduction of the lower face, associated with antero-posterior development of the braincase occurring (possibly in parallel evolution) along distinct human lineages. Furthermore, Neandertals display a projection of the midface, and modern humans show a derived globularity of the vault associated with midsagittal parietal bulging. Principal Component Analysis demonstrates a bimodal pattern of variation, which describes an "archaic" pole (rather heterogeneous in terms of taxonomy) clearly distinguishable from the modern one. The first two principal components - that explain together 80% of the total variance in shape - involve respectively fronto-parietal expansion and midfacial prognathism. These results contribute to identify different structural patterns in human evolution, supporting discontinuity rather than continuity of cranial shape among different taxa of the genus Homo, especially when considering the differences between Neandertals and early modern humans. PMID:15636068

Bruner, Emiliano; Saracino, Barbara; Ricci, Francesca; Tafuri, Maryanne; Passarello, Pietro; Manzi, Giorgio

2004-06-01

313

Early Origin for Human-Like Precision Grasping: A Comparative Study of Pollical Distal Phalanges in Fossil Hominins  

PubMed Central

Background The morphology of human pollical distal phalanges (PDP) closely reflects the adaptation of human hands for refined precision grip with pad-to-pad contact. The presence of these precision grip-related traits in the PDP of fossil hominins has been related to human-like hand proportions (i.e. short hands with a long thumb) enabling the thumb and finger pads to contact. Although this has been traditionally linked to the appearance of stone tool-making, the alternative hypothesis of an earlier origin—related to the freeing of the hands thanks to the advent of terrestrial bipedalism—is also possible given the human-like intrinsic hand proportion found in australopiths. Methodology/Principal Findings We perform morphofunctional and morphometric (bivariate and multivariate) analyses of most available hominin pollical distal phalanges, including Orrorin, Australopithecus, Paranthropous and fossil Homo, in order to investigate their morphological affinities. Our results indicate that the thumb morphology of the early biped Orrorin is more human-like than that of australopiths, in spite of its ancient chronology (ca. 6 Ma). Moreover, Orrorin already displays typical human-like features related to precision grasping. Conclusions These results reinforce previous hypotheses relating the origin of refined manipulation of natural objects–not stone tool-making–with the relaxation of locomotor selection pressures on the forelimbs. This suggests that human hand length proportions are largely plesiomorphic, in the sense that they more closely resemble the relatively short-handed Miocene apes than the elongated hand pattern of extant hominoids. With the advent of terrestrial bipedalism, these hand proportions may have been co-opted by early hominins for enhanced manipulative capabilities that, in turn, would have been later co-opted for stone tool-making in the genus Homo, more encephalized than the previous australopiths. This hypothesis remains may be further tested by the finding of more complete hands of unequivocally biped early hominins.

Almecija, Sergio; Moya-Sola, Salvador; Alba, David M.

2010-01-01

314

Diet in Early Homo : A Review of the Evidence and a New Model of Adaptive Versatility  

Microsoft Academic Search

Several recent studies have stressed the role of dietary change in the origin and early evolution of our genus in Africa. Resulting models have been based on nutrition research and analogy to living peoples and nonhuman primates or on archeological and paleoenvironmen- tal evidence. Here we evaluate these models in the context of the hominin fossil record. Inference of diet

Peter S. Ungar; Frederick E. Grine; Mark F. Teaford

2006-01-01

315

Synthetic Trace Fossils using mechanical bugs  

NSDL National Science Digital Library

This activity is suitable for either an hour-long in class activity or a longer laboratory. It explores trace fossils by creating tracks in various substrates using mechanical bugs (Hexbugs). Students analyze the traces without seeing how they were made, then get to explore the traces by playing with the mechanical bugs that made them and varying the substrate.

Cowan, Clint

316

Fossil-fuel constraints on global warming  

Microsoft Academic Search

In 2008 and 2009 two papers by Kharecha and Hansen and by Nel and Cooper examined possible fossil energy availability and energy consumption scenarios and consequences for future climate. The papers yield somewhat similar results regarding atmospheric CO2 levels, but they reach substantially different conclusions regarding future climate change. Here, we compare their methods and results. Our work shows that

Antonio Zecca; Luca Chiari

2010-01-01

317

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

318

Learning about Fossil Formation by Classroom Simulation.  

ERIC Educational Resources Information Center

Activities in which students build their own simulations of fossils, using seashells, chicken bones, toy dinosaurs, or leaves as models and plaster of paris, sand, mud, clay, or a mixture of gravel and clay as a matrix are presented. Curriculum extensions are included. (KR)

Schlenker, Richard M.; Yoshida, Sarah J.

1991-01-01

319

Thermal dissolution of solid fossil fuels  

SciTech Connect

The use of oil shales and coals in the processes of thermal dissolution is considered. It is shown that thermal dissolution is a mode of liquefaction of solid fossil fuels and can be used both independently and in combination with liquefaction of coals and processing of heavy petroleum residues.

E.G. Gorlov [Institute for Fossil Fuels, Moscow (Russian Federation)

2007-10-15

320

Fossilized gravitational wave relic and primordial clocks  

NASA Astrophysics Data System (ADS)

If long-wavelength primordial tensor modes are coupled to short-wavelength scalar modes, the scalar curvature two-point function will have an off-diagonal component. This "fossil" remnant is a signature of a mode coupling that cannot be achieved in single-clock inflation. Any constraint on its presence allows a cross-check of the relationship between the dynamical generation of the fluctuations and the evolution of the inflationary background. We use the example of non—Bunch-Davies initial states for the tensor and scalar modes to demonstrate that physically reasonable fossils, consistent with current data, can be observable in the near future. We illustrate how the fossil off-diagonal power spectrum is a complementary probe to the squeezed limit bispectra of the scalar and tensor sectors individually. We also quantify the relation between the observable signal and the squeezed limit bispectrum for a general scalar-scalar-fossil coupling and note the effect of superhorizon tensor modes on the anisotropy in scalar modes.

Brahma, Suddhasattwa; Nelson, Elliot; Shandera, Sarah

2014-01-01

321

A Fungal Analog for Newfoundland Ediacaran Fossils?  

Microsoft Academic Search

SYNOPSIS. We propose that some of the more conspicuous Ediacaran fossils from the Avalon Peninsula of Newfoundland, including Aspidella, Charnia, and Charniodiscus, were biologically similar to members of the Kingdom Fungi. These organisms were multicellular or multinuclear, lived below the photic zone, could not move or defoul themselves, did not exhibit taphonomic shrinkage, and were not transported or moved. Aspidella,

KEVIN J. PETERSON; B EN WAGGONER; JAMES W. H AGADORN

2003-01-01

322

New technologies in fossil-fuel utilization  

Microsoft Academic Search

This document contains the outline and viewgraphs used in the speech. Topics covered are: conventional oil and gas recovery; unconventional oil and gas sources; oil shale resources; conventional coal combustion; advanced fossil power systems; fluidized bed combustion; coal\\/oil or coal\\/water mixtures; and gaseous and liquid fuels from coal. (DMC)

1982-01-01

323

Cliffwood Beach Fossil Preserve Environmental Assessment.  

National Technical Information Service (NTIS)

The Fossil Preserve built as part of the Cliffwood Beach Shore Protection project in the mid 1970's is important to scientists. The Township of Aberdeen now wants the Preserve filled to halt further cliff erosion and avoid safety problems. Before filling ...

1982-01-01

324

Fossil Energy Materials Program conference proceedings  

SciTech Connect

The US Department of Energy Office of Fossil Energy has recognized the need for materials research and development to assure the adequacy of materials of construction for advanced fossil energy systems. The principal responsibility for identifying needed materials research and for establishing a program to address these needs resides within the Office of Technical Coordination. That office has established the Advanced Research and Technology Development (AR and TD) Fossil Energy Materials Program to fulfill that responsibility. In addition to the AR and TD Materials Program, which is designed to address in a generic way the materials needs of fossil energy systems, specific materials support activities are also sponsored by the various line organizations such as the Office of Coal Gasification. A conference was held at Oak Ridge, Tennessee on May 19-21, 1987, to present and discuss the results of program activities during the past year. The conference program was organized in accordance with the research thrust areas we have established. These research thrust areas include structural ceramics (particularly fiber-reinforced ceramic composites), corrosion and erosion, and alloy development and mechanical properties. Eighty-six people attended the conference. Papers have been entered individually into EDB and ERA. (LTN)

Judkins, R.R. (comp.)

1987-08-01

325

Fossils: An Ancient Sea in Indiana  

NSDL National Science Digital Library

In this interactive activity from the Children's Museum of Indianapolis, Indiana, examine a piece of the ancient Borden Sea in what is now central Indiana. Explore the types of fossils found there and the clues they offer to ancient life on Earth.

Foundation, Wgbh E.

2005-10-21

326

Insect Diversity in the Fossil Record  

Microsoft Academic Search

Insects possess a surprisingly extensive fossil record. Compilation of the geochronologic ranges of insect families demonstrates that their diversity exceeds that of preserved vertebrate tetrapods through 91 percent of their evolutionary history. The great diversity of insects was achieved not by high origination rates but rather by low extinction rates comparable to the low rates of slowly evolving marine invertebrate

Conrad C. Labandeira; J. John Sepkoski Jr.

1993-01-01

327

On the fossil record of the Gekkota.  

PubMed

Gekkota is often interpreted as sister to all remaining squamates, exclusive of dibamids, or as sister to Autarchoglossa. It is the only diverse lineage of primarily nocturnal lizards and includes some of the smallest amniotes. The skeleton of geckos has often been interpreted as paedomorphic and/or "primitive" but these lizards also display a wide range of structural specializations of the postcranium, including modifications associated with both scansorial locomotion and limb reduction. Although the concept of "Gekkota" has been variously applied by different authors, we here apply a rigorous apomorphy based definition, recent advances in gekkotan morphology and phylogenetics, and diverse comparative material to provide a comprehensive assessment of 28 known pre-Quaternary geckos, updating the last such review, published three decades ago. Fossils evaluated include both sedimentary fossils and amber-embedded specimens. Known Cretaceous geckos are exclusively Asian and exhibit character combinations not seen in any living forms. Cenozoic gekkotans derive from sites around the world, although Europe is especially well represented. Paleogene geckos are largely known from disarticulated remains and show similarities to Sphaerodactylidae and Diplodactylidae, although resemblances may be plesiomorphic in some cases. Many Neogene gekkotans are referable to living families or even genera, but their geographic occurrences are often extralimital to those of modern groups, as is consistent with paleoclimatic conditions. The phylogenetic placement of fossil gekkotans has important repercusions for timetree calibration, but at present only a small number of fossils can be confidently assigned to even family level groupings, limiting their utility in this regard. PMID:24482344

Daza, Juan D; Bauer, Aaron M; Snively, Eric D

2014-03-01

328

Fossils of reionization in the local group  

SciTech Connect

We use a combination of high-resolution gas dynamics simulations of high-redshift dwarf galaxies and dissipationless simulations of a Milky Way sized halo to estimate the expected abundance and spatial distribution of the dwarf satellite galaxies that formed most of their stars around z {approx} 8 and evolved only little since then. Such galaxies can be considered as fossils of the reionization era, and studying their properties could provide a direct window into the early, pre-reionization stages of galaxy formation. We show that 5-15% of the objects existing at z {approx} 8 do indeed survive until the present in the MW like environment without significant evolution. This implies that it is plausible that the fossil dwarf galaxies do exist in the Local Group. Because such galaxies form their stellar systems early during the period of active merging and accretion, they should have spheroidal morphology regardless of their current distance from the host galaxy. We show that both the expected luminosity function and spatial distribution of dark matter halos which are likely to host fossil galaxies agree reasonably well with the observed distributions of the luminous (L{sub V} > 10{sup 6} Lsun) Local Group fossil candidates near the host galaxy (d<200 kpc). However, the predicted abundance is substantially larger (by a factor of 2-3) for fainter galaxies (L{sub V} < 10{sup 6} Lsun) at larger distances (d>300 kpc). We discuss several possible explanations for this discrepancy.

Gnedin, Nickolay Y.; /Fermilab /KICP, Chicago /Chicago U., EFI; Kravtsov, Andrey V.; /KICP, Chicago /Chicago U., EFI /Chicago U., Astron. Astrophys. Ctr.

2006-01-01

329

Fossil birds of the Kibish Formation  

Microsoft Academic Search

The Kibish Formation has yielded a small collection of bird fossils, which are identified here as belonging to five species in four different families: Pelecanidae (pelicans), Anhingidae (darters), Ardeidae (herons) and Phasianidae (gamefowl). Two species of pelicans are identified: Pelecanus cf. P. onocrotalus, and P. aff. P. rufescens. The darter is referrable to Anhinga melanogaster. The heron is identifiable as Ardea

Antoine Louchart

2008-01-01

330

Atmospheric Sulfur and Fossil Fuel Combustion  

Microsoft Academic Search

Sulfate-chloride ratios in ice samples from the Greenland ice sheet indicate that the combustion of fossil fuels is now introducing slightly more sulfur into the atmosphere than such natural processes as volcanism and the oxidation of hydrogen sulfide derived from organic matter. The amount of sulfate co-varies with the amount of lead in the recent glacial strata, which fact suggests

Minoru Koide; Edward D. Goldberg

1971-01-01

331

Realistic ocean energy alternatives to fossil fuels  

Microsoft Academic Search

The US Commission on Ocean Policy endorsed the Administrations complete dependence on fossil fuels as the primary energy source for the nation. Two very significant alternatives were rejected or neglected. The first alternative was sea based semi submerged nuclear power plant ships deployed in a line paralleling the coastline of the United States. The US has developed and deployed hundreds

John Piña Craven

2005-01-01

332

Solar hydrogen: Moving beyond fossil fuels  

Microsoft Academic Search

The prospect of using hydrogen from water as a substitute for oil and other fossil fuels has moved from the realm of dream to distinct possibility. What has made hydrogen worth reconsidering now are recent dramatic developments in photovoltaic (PV) cells that directly convert sunlight into electricity. This book discusses the advantages of a hydrogen-based economy and how such a

J. M. Ogden; R. H. Williams

1989-01-01

333

The Fascinating Story of Fossil Fuels  

ERIC Educational Resources Information Center

How this energy source was created, its meaning to mankind, our drastically reduced supply, and why we cannot wait for nature to make more are considered. Today fossil fuels supply 96 percent of the energy used but we must find alternate energy options if we are to combat the energy crisis. (BL)

Asimov, Isaac

1973-01-01

334

An interesting new fossil dragonfly (Anisoptera: Libellulidae: \\  

Microsoft Academic Search

Summary A new dragonfly species, Parabrachydiplax miocenica n. gen. n. sp. (Anisoptera: Libelluli- dae), is described from the early Middle Miocene of Heggbach in southern Germany. The holotype was collected by the priest J. PROBST in 1865 and represents the earliest record of fossil insect remains from the Upper Freshwater Molasse of Baden-Württemberg. The phylo- genetic position of this new

Volker J. Sach

335

Homo-epitaxial growth on misoriented GaN substrates by MOCVD[Metal Organic Chemical Vapor Deposition  

SciTech Connect

The N-side of GaN single crystals with off-angle orientations of 0{degree}, 2{degree}, and 4{degree} towards the [10{bar 1}0] direction was used as a substrate for homo-epitaxial MOCVD growth. The highest misorientation resulted in a reduction of the density of grown hillocks by almost two orders of magnitude as compared with homo-epitaxial films grown on the exact (000{bar 1}) surface. The features still found on the 4{degree} misoriented sample after growth can be explained by a model involving the interaction of steps, introduced by the misorientation and the hexagonal hillocks during the growth process.

Zauner, A.R.A.; Schermer, J.J.; Enckevort, W.J.P. van; Kirilyuk, V.; Weyher, J.L.; Grzegory, I.; Hageman, P.R.; Larsen, P.K.

2000-07-01

336

Models of diffusion-limited uptake of trace elements in fossils and rates of fossilization  

NASA Astrophysics Data System (ADS)

Many fossils are assumed to take up trace elements by a process of combined diffusion plus adsorption (DA), yet in principle composition profiles can be explained by several different diffusion-limited processes, including diffusion plus reaction or recrystallization (DR) and double-medium diffusion (DMD). The DA and DMD models are supported by REE and U composition profiles across fossil teeth, measured by laser-ablation ICP-MS, that show error-function - like diffusion profiles into enamel from the dentine-enamel interface and concentrations in the interior of enamel that are at original biogenic levels or higher. Published composition and age profiles in some Pleistocene bones may be better explained by a DR model. All three diffusion models imply linear behavior between age and distance squared, vastly simplifying U-series dating methods for Pleistocene fossils. Modeled uptake rates for fossil teeth yield a strict minimum bound on durations of about one decade to one century. The similarity of diffusion profiles in teeth, irrespective of depositional ages ranging from ˜30 ka to >30 Ma, implies that uptake occurred quickly, with a maximum duration of a few tens of kyr for typical fossil enamel; faster uptake is implied for typical fossil bone and dentine. Disparities in these uptake estimates compared to some archeological bone may reflect sampling and preservation bias for paleontological vs. archeological materials.

Kohn, Matthew J.

2008-08-01

337

Fossil Woodwardia virginica Foliage From the Middle Miocene Yakima Canyon  

NSDL National Science Digital Library

Fossil Woodwardia virginica foliage from the middle Miocene Yakima Canyon flora of central Washington State, USA. Vegetative and fertile features of this fossil are remarkably similar to those of the modern ""Virginia chain fern"" of the Atlantic coastal region, USA.

Kathleen B. Pigg (Arizona State University;Department of Plant Biology ADR;POSTAL)

2004-03-09

338

Evaluation of Hybrid Solar/Fossil Rankine-Cooling Concept.  

National Technical Information Service (NTIS)

The hybrid solar/fossil Rankine cycle is analyzed thermodynamically to determine fuel use and efficiency. The hybrid system is briefly compared with solar organic Rankine systems with a fossil fuel auxiliary mode, and with geothermal resources. The econom...

H. M. Curran

1980-01-01

339

Advanced Research and Technology Development Fossil Energy Materials Program.  

National Technical Information Service (NTIS)

The Advanced Research and Technology Development (AR and TD) Fossil Energy Materials Program is a multifaceted materials research and development program sponsored by the Office of Fossil Energy of the US Department of Energy. The program is administered ...

R. R. Judkins R. A. Bradley

1987-01-01

340

Fossil Record Accurately Reflects Recent Flowering of Marine Biodiversity  

NSF Publications Database

... Lane (703) 292-8550 hlane@nsf.gov Fossil Record Accurately Reflects Recent Flowering of Marine ... produced by the inconsistencies of the fossil record, says a team of paleontologists led by the ...

341

DFT, FT-Raman, FT-IR, HOMO-LUMO and NBO studies of 4-Methylmorpholine.  

PubMed

The experimental FT-IR (4000-400 cm(-1)) and FT-Raman (3500-100 cm(-1)) spectra of 4-Methylmorpholine were recorded. The observed bands were interpreted with the aid of normal coordinate analysis and force field calculations based on density functional theory (DFT) using B3LYP functional theory (DFT) using B3LYP functional with 6-311+G and 6-3++G basis sets. The complete assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. The molecular structure and vibrational frequencies, infrared intensities and Raman scattering actives have been calculated frequency showed the best agreement with experimental results. The formation of the hydrogen bond was investigated using NBO calculations. The calculated HOMO and LUMO energies show that charge transfer occur within the molecule. The dipolemoment (?) and polarizability (?), anisotropy polarizability (??) and first hyperpolarizability (?(total)) of the molecule have been reported. PMID:22929905

Balachandran, V; Mahalakshmi, G; Lakshmi, A; Janaki, A

2012-11-01

342

Syntheses and antiproliferative effects of d-homo- and d-secoestrones.  

PubMed

Substituted and/or heterocyclic d-homoestrone derivatives were synthetized via the intramolecular cyclization of a ?-alkenyl-d-secoaldehyde, -d-secoalcohol or -d-secocarboxylic acid of estrone 3-benzyl ether. The d-secoalcohol was modified at three sites in the molecule. The in vitro antiproliferative activities of the new d-homo- and d-secoestrone derivatives were determined on HeLa, MCF-7, A431 and A2780 cells through use of MTT assay. d-Homoalcohols 3 and 5 displayed cell line-selective cytostatic effects against ovarian and cervical cell lines, respectively. Two d-secoestrones (6 and 12c) proved to be effective, with IC50 values comparable with those of the reference agent cisplatin. A selected compound (6) was tested by tubulin polymerization assay and its cancer specificity was additionally determined by using noncancerous human fibroblast cells. PMID:24928727

Mernyák, Erzsébet; Szabó, Johanna; Bacsa, Ildikó; Huber, Judit; Schneider, Gyula; Minorics, Renáta; Bózsity, Noémi; Zupkó, István; Varga, Mónika; Bikádi, Zsolt; Hazai, Eszter; Wölfling, János

2014-09-01

343

Vibrational spectroscopic investigations, first hyperpolarizability, HOMO-LUMO and NMR analyzes of p-fluorobenzonitrile.  

PubMed

Quantum chemical density functional calculations were carried out for PFBN with the GAUSSIAN 09W using ab initio and Becke-3-Lee-Yang-Parr (B3LYP) functional. The observed FT-IR and FT-Raman vibrational frequencies are analyzed and compared with theoretically predicted vibrational frequencies. The geometries and normal modes of vibration obtained from DFT method are in good agreement with the experimental data. The first-order hyperpolarizability (?) of the investigated molecule was computed using DFT calculations. The calculated HOMO and LUMO energies shows that charge transfer occur within molecule. The influences of nitrogen on the geometry of benzene and its normal modes of vibrations have also been discussed. The UV-Vis spectral analysis of PFBN has also been done which confirms the charge transfer of PFBN. The chemical shifts of H atoms and C atoms were calculated using NMR analysis. PMID:23201569

Arivazhagan, M; Meenakshi, R; Prabhakaran, S

2013-02-01

344

The living fossil of human judgment.  

PubMed

Although the biases and anomalies characterizing psychometric data should serve as conclusive evidence of systematic flaws in scientific methodology, these problems are usually ignored, which reduces empirical psychology to the closed system of its error theory. However, psychometric scores are ambiguous, and response-shifts and fluctuating validities point to fundamental differences in what the measuring-apparatus questionnaire records and how the measuring-apparatus person judges. Therefore, empirical methods fail when psychology requires evidence-based knowledge about cognitive processes and phenomena. Correcting these flaws requires a reassessment of basic scientific premises and careful consideration of Homo sapiens' biosemiotic heuristics. Based on comprehensive biopsychosocial, data, the author reconstructs the evolutionary axioms of self-referenced cognitions and reveals what is usually obscured by the axioms of normal science. He substantiates the need for a paradigm shift toward basic bio-cultural principles and an evolutionary understanding of human thinking and behavior. PMID:24615167

Schwarz, Michael

2014-06-01

345

Construction of a constitutively expressed homo-fermentative pathway in Lactobacillus brevis.  

PubMed

Lactobacillus brevis is a promising lactic acid producing strain that simultaneously utilizes glucose and xylose from lignocellulosic hydrolysate without carbon catabolic repression and inhibition. The production of by-products acetic acid and ethanol has been the major drawback of this strain. Two genes, pfkA (fructose-6-phosphate kinase [PFK]) and fbaA (fructose-1,6-biphosphate aldolase [FBA]), that encode the key enzymes of the EMP/glycolytic pathway from Lactobacillus rhamnosus, were fused to the downstream of the strong promoter P32 and expressed in L. brevis s3f4 as a strategy to minimize the formation of by-products. By expressing the two enzymes, a homo-fermentative pathway for lactic acid production was constructed. The lactic acid yields achieved from glucose in the transformants were 1.12 and 1.16 mol/mol, which is higher than that of the native strain (0.74 mol/mol). However, the lactic acid yield from xylose in the transformants stayed the same as that of the native strain. Enzyme assay indicated that the activity of the foreign protein FBA in the transformants was much higher than that of the native strains, but was ten times lower than that in L. rhamnosus. This result was consistent with the metabolic flux analysis, which indicated that the conversion efficiency of the expressed PFK and FBA was somewhat low. Less than 20 % of the carbons accumulated in the form of fructose-6-phosphate were converted into glyceraldehyde-3-phosphate (GAP) by the expressed PFK and FBA. Metabolic flux analysis also indicated that the enzyme phosphoketolase (XPK) played an important role in splitting the carbon flow from the pentose phosphate pathway to the phosphoketolase pathway. This study suggested that the lactic acid yield of L. brevis could be improved by constructing a homo-fermentative pathway. PMID:24728715

Guo, Wei; He, Ronglin; Ma, Lijuan; Jia, Wendi; Li, Demao; Chen, Shulin

2014-08-01

346

Nonlinear Socio-Ecological Dynamics and First Principles ofCollective Choice Behavior of ``Homo Socialis"  

NASA Astrophysics Data System (ADS)

Socio-ecological dynamics emerged from the field of Mathematical SocialSciences and opened up avenues for re-examination of classical problems of collective behavior in Social and Spatial sciences. The ``engine" of this collective behavior is the subjective mental evaluation of level of utilities in the future, presenting sets of composite socio-economic-temporal-locational advantages. These dynamics present new laws of collective multi-population behavior which are the meso-level counterparts of the utility optimization individual behavior. The central core of the socio-ecological choice dynamics includes the following first principle of the collective choice behavior of ``Homo Socialis" based on the existence of ``collective consciousness": the choice behavior of ``Homo Socialis" is a collective meso-level choice behavior such that the relative changes in choice frequencies depend on the distribution of innovation alternatives between adopters of innovations. The mathematical basis of the Socio-Ecological Dynamics includes two complementary analytical approaches both based on the use of computer modeling as a theoretical and simulation tool. First approach is the ``continuous approach" --- the systems of ordinary and partial differential equations reflecting the continuous time Volterra ecological formalism in a form of antagonistic and/or cooperative collective hyper-games between different sub-sets of choice alternatives. Second approach is the ``discrete approach" --- systems of difference equations presenting a new branch of the non-linear discrete dynamics --- the Discrete Relative m-population/n-innovations Socio-Spatial Dynamics (Dendrinos and Sonis, 1990). The generalization of the Volterra formalism leads further to the meso-level variational principle of collective choice behavior determining the balance between the resulting cumulative social spatio-temporal interactions among the population of adopters susceptible to the choice alternatives and the cumulative equalization of the power of elites supporting different choice alternatives. This balance governs the dynamic innovation choice process and constitutes the dynamic meso-level counterpart of the micro-economic individual utility maximization principle.

Sonis, M.

347

New form of information from T. rex and Mastodon fossils  

NSDL National Science Digital Library

After discovering a giant T. rex leg bone fossil in Montana, back in 2003, a team of scientists had a problem: It wouldn't fit in their helicopter. When they broke the fossil open in order to fit the pieces inside, this led to a shocking discovery. Some of the dinosaur's soft tissues such as blood vessels were still present inside the fossil.

American Association for the Advancement of Science (AAAS;)

2007-04-12

348

Development of concepts for a zero-fossil-energy greenhouse  

Microsoft Academic Search

Dutch government and greenhouse horticultural practice aim for strongly reduced fossil energy use and of environmental loads in 2010 and energy neutral greenhouses in 2020. This research aims to design a greenhouse concept with minimal use of fossil energy and independent of nearby greenhouses. The concept is called the zero-fossil-energy-greenhouse. This paper presents a theoretical design study and analysis to

Ooster van't A; Henten van E. J; E. G. O. N. Janssen; G. P. A. Bot; E. Dekker

2008-01-01

349

Identification of Common Fossil Organisms for Introductory Geology.  

ERIC Educational Resources Information Center

Provides a format for the identification of fossils when introducing geologic time in the laboratory. Presents an organization of fossils into three major groups based on radial, bilateral, and no apparent symmetry. States that this method reinforces student learning and provides for an orderly approach to fossils. (RT)

Davis, Larry Eugene; Eves, Robert Leo

1988-01-01

350

First Fossil Lamprey: A Record from the Pennsylvanian of Illinois  

Microsoft Academic Search

A fossil record of lampreys has previously been unknown. A new genus demonstrates the presence of this group in the Pennsylvanian. The body outline, parts of the head skeleton, rasping tongue mechanism, gill basket, and other internal organs are preserved. The fossils are very similar in structure to modern forms. The absence of hagfish characters in the fossil supports the

David Bardack; Rainer Zangerl

1968-01-01

351

Three new fossil landbirds from the early Paleogene of Denmark  

Microsoft Academic Search

Well-preserved remains of fossil modern birds are rare, especially from the earliest stages of their evolution. In this paper we describe three new fossil specimens that can be referred to two of the major clades of extant 'landbirds', namely Apodiformes ('swifts') and Coliiformes ('mousebirds'). Because the fossils presented here are from the earliest tertiary of Denmark, they represent some of

GARETH J. DYKE; DAVID M. WATERHOUSE; ANETTE V. KRISTOFFERSEN

2004-01-01

352

The United Kingdom's Fossil Resource Consumption Between 1968 and 2000  

Microsoft Academic Search

SummaryThis article presents the trends of two indicators measuring fossil resource consumption in the United Kingdom (UK). First, a domestic material consumption (DMC) indicator for fossil resources (DMCfossil) in the mass unit million tonnes is calculated. DMCfossil shows that between 1970 and 2000 UK fossil resource consumption decreased by 10%, which suggests absolute dematerialization for this resource. Investigation into the

Eleni Papathanasopoulou; Tim Jackson

2010-01-01

353

Palaeomagnetic analysis of the Sterkfontein palaeocave deposits: implications for the age of the hominin fossils and stone tool industries.  

PubMed

Palaeomagnetic analysis was conducted on speleothems from Members 1-5 at Sterkfontein Cave, South Africa. Palaeomagnetic analysis of siltstone and speleothem from the bulk of Member 4 indicate a reversed magnetic polarity that dates the deposits and its Australopithecus africanus fossils to between 2.58 and ~2.16 Ma. Further confirmation of this age comes in the form of two short normal polarity events correlated to the Rèunion (~2.16 Ma) and Huckleberry Ridge (~2.05 Ma) events in speleothem capping the bulk of Member 4 and coeval with deposition of the final phase of Member 4, including A. africanus fossil Sts 5. At ~2.16-2.05 Ma, Sts 5 is the youngest representative of A. africanus yet discovered. Palaeomagnetic analysis of the Silberberg Grotto deposits identifies a single short geomagnetic field event in flowstone overlying the StW 573 Australopithecus fossil, which is suggested to represent the Rèunion event at ~2.16 Ma. This further supports the uranium lead age estimates of 2.3-2.2 Ma for the StW 573 fossil. Based on a reversed polarity for the deposits below the skeleton it cannot be older than 2.58 Ma. If StW 573 is considered to be a second species of Australopithecus then this indicates that two species of Australopithecus are present at Sterkfontein between 2.6 and 2.0 Ma. All of the Member 5 deposits date to less than 1.8 Ma based on a comparison of palaeomagnetic, faunal, and electron spin resonance age estimates. The StW 53 fossil bearing infill (M5A) is intermediate in age between Member 4 and the rest of Member 5 (B-C) at around 1.78-1.49 Ma. The rest of Member 5 (B-C) containing Oldowan and Acheulian stone tools and Homo and Paranthropus fossils was deposited gradually between 1.40 and 1.07 Ma, much younger than previously suggested. PMID:21392817

Herries, Andy I R; Shaw, John

2011-05-01

354

Fossil groups in the local Universe  

NASA Astrophysics Data System (ADS)

In a hierarchically evolving universe, the oldest and most undisturbed galaxy systems are low mass groups which have not yet been absorbed into larger halos. Such 'fossil groups' consist of a giant elliptical galaxy embeded in a large, group-scale halo of hot gas. Only a handful of these objects have been studied so far, and their properties point to their being repositories of the lowest entropy and least disrupted intergalactic gas present in collapsed halos. We propose to observe two of the closest known fossil groups, in order to establish their properties as a class. Moreover, these observations will enable us to probe gas physics in conditions which are uniquely susceptible to radiative cooling instabilities, thereby providing a critical test of gas heating and feedback models.

Sanderson, Alastair

2004-09-01

355

Structural coloration in a fossil feather  

PubMed Central

Investigation of feathers from the famous Middle Eocene Messel Oil Shale near Darmstadt, Germany shows that they are preserved as arrays of fossilized melanosomes, the surrounding beta-keratin having degraded. The majority of feathers are preserved as aligned rod-shaped eumelanosomes. In some, however, the barbules of the open pennaceous, distal portion of the feather vane are preserved as a continuous external layer of closely packed melanosomes enclosing loosely aligned melanosomes. This arrangement is similar to the single thin-film nanostructure that generates an iridescent, structurally coloured sheen on the surface of black feathers in many lineages of living birds. This is, to our knowledge, the first evidence of preservation of a colour-producing nanostructure in a fossil feather and confirms the potential for determining colour differences in ancient birds and other dinosaurs.

Vinther, Jakob; Briggs, Derek E. G.; Clarke, Julia; Mayr, Gerald; Prum, Richard O.

2010-01-01

356

Structural coloration in a fossil feather.  

PubMed

Investigation of feathers from the famous Middle Eocene Messel Oil Shale near Darmstadt, Germany shows that they are preserved as arrays of fossilized melanosomes, the surrounding beta-keratin having degraded. The majority of feathers are preserved as aligned rod-shaped eumelanosomes. In some, however, the barbules of the open pennaceous, distal portion of the feather vane are preserved as a continuous external layer of closely packed melanosomes enclosing loosely aligned melanosomes. This arrangement is similar to the single thin-film nanostructure that generates an iridescent, structurally coloured sheen on the surface of black feathers in many lineages of living birds. This is, to our knowledge, the first evidence of preservation of a colour-producing nanostructure in a fossil feather and confirms the potential for determining colour differences in ancient birds and other dinosaurs. PMID:19710052

Vinther, Jakob; Briggs, Derek E G; Clarke, Julia; Mayr, Gerald; Prum, Richard O

2010-02-23

357

FOSSIL RIDGE WILDERNESS STUDY AREA, COLORADO.  

USGS Publications Warehouse

The Fossil Ridge Wilderness Study Area, approximately 20 mi northeast of Gunnison in central Colorado, was studied and its mineral-resource potential assessed. Portions of the study area have substantiated resource potential for gold, silver, copper, lead, zinc, molybdenum, uranium, thorium, rare-earth elements, and high-calcium limestone. Much of the area has a probable resource potential for the preceeding commodities as well as for tin. Various other elements are found in anomalous concentrations within the study area, but there is likelihood for their occurrence in amounts sufficient to constitute resources. Exploration, especially for molybdenum, gold, and uranium, has been active in the past and is expected to continue in the future. No potential for fossil fuel resources was identified in this study.

DeWitt, Ed; Kluender, Steven, E.

1984-01-01

358

Diatoms: a fossil fuel of the future.  

PubMed

Long-term global climate change, caused by burning petroleum and other fossil fuels, has motivated an urgent need to develop renewable, carbon-neutral, economically viable alternatives to displace petroleum using existing infrastructure. Algal feedstocks are promising candidate replacements as a 'drop-in' fuel. Here, we focus on a specific algal taxon, diatoms, to become the fossil fuel of the future. We summarize past attempts to obtain suitable diatom strains, propose future directions for their genetic manipulation, and offer biotechnological pathways to improve yield. We calculate that the yields obtained by using diatoms as a production platform are theoretically sufficient to satisfy the total oil consumption of the US, using between 3 and 5% of its land area. PMID:24529448

Levitan, Orly; Dinamarca, Jorge; Hochman, Gal; Falkowski, Paul G

2014-03-01

359

Fossil energy review, July--September 1991  

SciTech Connect

This report is a quarterly update of key events in the Department of Energy`s Fossil Energy program, published for business, industry and academic researchers. Articles in this update include: Nine Clean Coal Projects Chosen; Testing of Acid Rain Control System Begins in Pennsylvania; Tallahassee Opts not to Proceed with Clean Coal ``Fluidized Bed`` Project; DOE Schedules Clean Coal Round {number_sign}5 Public Meetings; Costs, Mixed Results End TransAlta Project; DOE Opens Competition for First Oil Field Tests; DOE, LSU to Study Bypassed Oil in Gulf of Mexico Offshore Fields; DOE to Cofund Study of Coal Wastes for Land Reclamation; DOE, VA Move Hospital Waste-Coal Cofiring Demo Project to Next Stage; R&D Teams Chosen to Bring Oil-from-Coal Costs to $30 per Barrel; US, Soviet Union Discuss Fossil Fuels Cooperation Following G-7 Summit; Cavern Space Created for Initial SPR Oil Target; and DOE Choses Texaco, Unocal to Expand SPR Distribution System.

Not Available

1991-12-31

360

Fossil energy review, July--September 1991  

SciTech Connect

This report is a quarterly update of key events in the Department of Energy's Fossil Energy program, published for business, industry and academic researchers. Articles in this update include: Nine Clean Coal Projects Chosen; Testing of Acid Rain Control System Begins in Pennsylvania; Tallahassee Opts not to Proceed with Clean Coal Fluidized Bed'' Project; DOE Schedules Clean Coal Round {number sign}5 Public Meetings; Costs, Mixed Results End TransAlta Project; DOE Opens Competition for First Oil Field Tests; DOE, LSU to Study Bypassed Oil in Gulf of Mexico Offshore Fields; DOE to Cofund Study of Coal Wastes for Land Reclamation; DOE, VA Move Hospital Waste-Coal Cofiring Demo Project to Next Stage; R D Teams Chosen to Bring Oil-from-Coal Costs to $30 per Barrel; US, Soviet Union Discuss Fossil Fuels Cooperation Following G-7 Summit; Cavern Space Created for Initial SPR Oil Target; and DOE Choses Texaco, Unocal to Expand SPR Distribution System.

Not Available

1991-01-01

361

Genetic evidence of an early exit of Homo sapiens sapiens from Africa through eastern Africa  

Microsoft Academic Search

The out-of-Africa scenario has hitherto provided little evidence for the precise route by which modern humans left Africa. Two major routes of dispersal have been hypothesized: one through North Africa into the Levant, documented by fossil remains, and one through Ethiopia along South Asia, for which little, if any, evidence exists. Mitochondrial DNA (mtDNA) can be used to trace maternal

Lluís Quintana-Murci; Ornella Semino; Hans-J. Bandelt; Giuseppe Passarino; Ken McElreavey; A. Silvana Santachiara-Benerecetti

1999-01-01

362

Problematic microscopic trace (?) fossils, Oligocene, Slovakia  

NASA Astrophysics Data System (ADS)

Meioscopic to microscopic capsules found in reddish, probably marine or brackish shales (Oligocene, Pannonian Basin; South Slovakia) are interpreted as possible trace fossils. They may represent burrows of meioscopic in-fauna. Ferruginous walls of the capsules appeared very probably as late as during diagenesis; however, the (possibly organic) matrix had to exist before the diagenetic processes. Other discussed explanations (inorganic "ironstones"; coprolites) are not plausible.

Mikuláš, R.; Boorová, D.; Holcová, K.

2013-05-01

363

Central heating: fossil-fired boilers  

Microsoft Academic Search

This evaluation provides performance and cost data for fossil-fuel-fired steam boilers, hot-water generators, and thermal fluid generators currently available from manufacturers. Advanced-technology fluidized-bed boilers also are covered. Performance characteristics investigated include unit efficiencies, turndown capacity, and pollution requirements. Costs are tabulated for equipment and installation of both field-erected and packaged units. The information compiled in this evaluation will assist in

C. F. Blazek; N. R. Baker; R. R. Tison

1979-01-01

364

Fossil pollen records of extant angiosperms  

Microsoft Academic Search

The fossil record for angiosperm pollen types which are comparable to recent taxa is evaluated, following a similar survey\\u000a published in 1970. Special attention is paid to the dating of the sediments. Evidence for 139 families is considered to be\\u000a reliable, for others the records are cited as provisional, pending the accumulation of more evidence. Some published records\\u000a are shown

Jan Muller

1981-01-01

365

Precambrian ``fossil'' Vermiforma is a tectograph  

SciTech Connect

Vermiforma antiqua Cloud 1976, once celebrated as the earliest animal fossil of the US, is actually a tectonic artifact. The main argument is that the congruence and equal orientation of multiple patterns on the same bedding plane are incompatible with swaying worm bodies of worm burrows. As shown by analog and numerical simulations, these structures can be explained as tracks of particles that broke out from the base of an overlying turbidite and became rolled between beds during bed-to-bed shearing.

Seilacher, A.; Meschede, M.; Bolton, E.W.; Luginsland, H.

2000-03-01

366

Oral Presentation of a Fossil Group  

NSDL National Science Digital Library

Each student chooses a different fossil group that interests him/her and prepares a 10 minute PowerPoint presentation about that group, lavishly illustrated and richly illuminated with fascinating facts! This can be as large a group as a phylum or as small as a species. Powerpoint handouts are given out during the oral presentation. Students must have a concluding slide citing references. The discussion must go beyond what is presented by the professor in lecture.

Reams, Max W.

367

IGT calculates world reserves of fossil fuels  

SciTech Connect

The Institute of Gas Technology has published the IGT World Reserves Survey, giving their latest tabulation of world reserves of fossil fuels and uranium. The report contains 120 Tables and 41 Figures. Estimates are provided for proved reserves, resources, current production, and life indexes of the non-renewable energy sources of the US and of the world as a whole. World regional data are also provided in many cases. The data are summarized here. 2 figures, 5 tables.

Not Available

1986-12-01

368

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

369

The First Turbulence and First Fossil Turbulence  

Microsoft Academic Search

A model is proposed connecting turbulence, fossil turbulence and the big-bang origin of the universe. While details are incomplete, the model is consistent with our knowledge of these processes and is supported by observations. Turbulence arises in a hot big-bang quantum gravitational dynamics scenario at Planck scales. Chaotic, eddy-like motions produce an exothermic Planck particle cascade from 10-35 m at

Carl H. Gibson

2004-01-01

370

Fossil dust shells around luminous supergiants  

NASA Technical Reports Server (NTRS)

The observed frequency with which infrared excesses appear in F, G, and K supergiants of luminosity class Ia supports the idea that these excesses arise in a 'fossil' circumstellar dust shell that was formed during a prior M-super-giant phase of evolution. The required leftward evolution of the star on the H-R diagram would then imply that the Ledoux, rather than the Schwarzschild, criterion for convective mixing is the correct criterion to use in stellar evolution calculations.

Stothers, R.

1975-01-01

371

In situ growth and density-functional-theory study of polarity-dependent homo-epitaxial ZnO microwires  

SciTech Connect

Polarity-dependent homo-epitaxy on (0001)-Zn and (0001)-O surfaces of cleaved ZnO microwires was investigated by in situ growth in ESEMand DFT simulations. ZnO monomers adsorption, adatoms desorption and chemisorption were simulated to understand the explicit mechanism.

Zhu, Rui [ORNL; Xu, Jun [ORNL; Gao, Jingyun [Peking University; Zhang, Jingmin [Peking University; Zhu, Wenguang [University of Tennessee, Knoxville (UTK); Xu, Hongjun [Peking University; Sun, Yanghui [Peking University; Fu, Qiang [Peking University; Chen, Li [Peking University; Du, Dapeng [Peking University

2012-01-01

372

Molecular biology of Homo sapiens: Abstracts of papers presented at the 51st Cold Spring Harbor symposium on quantitative biology  

SciTech Connect

This volume contains abstracts of papers presented at the 51st Cold Springs Harbor Symposium on Quantitative Biology. The topic for this meeting was the ''Molecular Biology of Homo sapiens.'' Sessions were entitled Human Gene Map, Human Cancer Genes, Genetic Diagnosis, Human Evolution, Drugs Made Off Human Genes, Receptors, and Gene Therapy. (DT)

Watson, J.D.; Siniscalco, M.

1986-01-01

373

Causal Assessment of Biological Impairment in the Bogue Homo River, Mississippi Using the U.S. EPA'S Stressor Identification Methodology.  

National Technical Information Service (NTIS)

This assessment of biological impairment in the Bogue Homo River, Mississippi is taken from more than 700 court ordered assessments of the causes of impairments requiring development of a total maximum daily load (TMDL). A TMDL is the calculation of the m...

A. Stewart J. Kurtz J. Thomas J. Whittington M. Hicks

2010-01-01

374

Response to comment on "A complete skull from Dmanisi, Georgia, and the evolutionary biology of early Homo".  

PubMed

Schwartz et al. hold that variation among the Dmanisi skulls reflects taxic diversity. The morphological observations to support their hypothesis, however, are partly incorrect, and not calibrated against intraspecific variation in living taxa. After proper adjustment, Schwartz et al.'s data are fully compatible with the hypothesis of a single paleodeme of early Homo at Dmanisi. PMID:24763573

Zollikofer, Christoph P E; Ponce de León, Marcia S; Margvelashvili, Ann; Rightmire, G Philip; Lordkipanidze, David

2014-04-25

375

A complete algorithm to resolve ambiguity for intersubunit NOE assignment in structure determination of symmetric homo-oligomers  

Microsoft Academic Search

Assignment of nuclear Overhauser effect (NOE) data is a key bottleneck in structure determination by NMR. NOE assignment resolves the ambiguity as to which pair of protons generated the observed NOE peaks, and thus should be restrained in structure determination. In the case of intersubunit NOEs in symmetric homo-oligomers, the ambiguity includes both the identities of the protons within a

SHOBHA POTLURI; ANTHONY K. YAN; BRUCE R. DONALD; CHRIS BAILEY-KELLOGG

2007-01-01

376

Life optimization for fossil fuel power plants  

SciTech Connect

During 1985 and 1986, EPRI funded several major studies of aging fossil-fuel power plants. These were aimed both at evaluation and planning on the plant level (life optimization), and condition assessment of individual components (life assessment). The experience gained during the execution of these projects, along with available international experience on the optimized use of existing power plants, was integrated in Generic Guidelines for the Life Extension of Fossil Fuel Power Plants,'' issued in November 1986 (CS-4778). These guidelines advocated the assessment of residual component life in increasingly detailed stages, the phased evaluation and refurbishment of equipment, the importance of integrated planning, and the requirement for application of data management techniques. To extend the procedures and methods presented in those generic guidelines, and to demonstrate the potential benefits of a formalized approach to the consideration of fossil fuel power plant evaluation, the Electric Power Research Institute initiated a technology transfer demonstration project, RP2596-10. This report provides a summary of the activities in that demonstration project. One of the tools that was developed during the project was a compilation of the condition assessment of 25 critical and major components. This report includes an overview of the Component Condition Assessment Guidelines, as well as other tools and analysis methods that were developed during the project. The project also served as a review of the application of the methods and procedures presented in the basic guidelines document; therefore, this report also includes an evaluation and suggested refinements of the generic guidelines.

McNaughton, W.P.; Richman, R.H. (Daedalus Associates, Inc., Mountain View, CA (USA)); Parker, J.D.; McMinn, A. (Failure Analysis Associates, Inc., Alexandria, VA (USA)); Bell, R.J. (Heat Exchanger Systems, Inc., Boston, MA (USA)); McCabe, P.; Leake, W.H. Jr. (EI International, Inc., Idaho Falls, ID (USA)); Dimmer, J.P.; Damon, J.E. (General Physics Corp., San Diego, CA (USA)); Brusger, E.C.; Farber, M.

1990-11-01

377

Age and metallicity gradients in fossil ellipticals  

NASA Astrophysics Data System (ADS)

Context. Fossil galaxy groups are speculated to be old and highly evolved systems of galaxies that formed early in the universe and had enough time to deplete their L? galaxies through successive mergers of member galaxies, building up one massive central elliptical, but retaining the group X-ray halo. Aims: Considering that fossils are the remnants of mergers in ordinary groups, the merger history of the progenitor group is expected to be imprinted in the fossil central galaxy (FCG). We present for the first time radial gradients of single-stellar population (SSP) ages and metallicites in a sample of FCGs to constrain their formation scenario. We also measure line-strength gradients for the strongest absorption features in these galaxies. Methods: We took deep spectra with the long-slit spectrograph ISIS at the William Herschel Telescope (WHT) for six FCGs. The obtained spectra are fit with Pegase HR SSP models within the full-spectrum fitting package ULySS yielding SSP ages and metallicities of the stellar populations. We measure radial gradients of SSP ages and metallicities along the major axes. Lick indices are measured for the strongest absorption features to determine line-strength gradients and compare with the full-spectrum fitting results. Results: Our sample comprises some of the most massive galaxies in the universe exhibiting an average central velocity dispersion of ?0 = 271 ± 28 km s-1. Metallicity gradients are throughout negative with comparatively flat slopes of ?[Fe/H] = -0.19 ± 0.08 while age gradients are found to be insignificant (?age = 0.00 ± 0.05). All FCGs lie on the fundamental plane, suggesting that they are virialised systems. We find that gradient strengths and central metallicities are similar to those found in cluster ellipticals of similar mass. Conclusions: The comparatively flat metallicity gradients with respect to those predicted by monolithic collapse (?Z = -0.5) suggest that fossils are indeed the result of multiple major mergers. Hence we conclude that fossils are not "failed groups" that formed with a top-heavy luminosity function. The low scatter of gradient slopes suggests a similar merging history for all galaxies in our sample. Figures 3 and 4 are available in electronic form at http://www.aanda.orgReduced spectra are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/553/A99

Eigenthaler, P.; Zeilinger, W. W.

2013-05-01

378

U Pb dating of fossil enamel from the Swartkrans Pleistocene hominid site, South Africa  

NASA Astrophysics Data System (ADS)

We demonstrate that young fossil enamel older than the range of the U-series (˜ 300 ka) can be dated by the U-Pb methods using new models of U and Pb loss and uptake. Contrary to the current hypothesis of U uptake that only considers the adsorption/diffusion mechanism, we here develop a complete time-dependent model which takes gains and losses of the most critical nuclides ( 238U, 234U, and 230Th) into account, both during chemical (dissolved U) and physical (Th and U ?-recoil) processes. Lead is assumed to be a mixture between two components of common Pb and a radiogenic component; the proportions of these components are calculated from the Pb isotope abundances and U/Pb ratios. We apply this new U-Pb method to bovid enamel from the Swartkrans Cave (Gauteng Province, South Africa). This cave has yielded abundant early Pleistocene hominid remains attributed to Paranthropus and Homo as well as various associated archaeological vestiges. Biochronological comparisons with East Africa have provided age estimates ranging between 1.8 and 1.0 Ma, which, however, remain poorly constrained. After correction for initial 234U disequilibrium and further 238U loss, the U and Pb isotope data yield ages of 1.83 ± 1.38, 1.36 ± 0.29, and 0.83 ± 0.21 Ma for the three stratigraphic units, Members 1, 2, and 3, respectively. We discuss the consequences of these radiometric results for hominid evolution in South Africa.

Balter, Vincent; Blichert-Toft, Janne; Braga, José; Telouk, Philippe; Thackeray, Francis; Albarède, Francis

2008-03-01

379

Traversing the mountaintop: world fossil fuel production to 2050  

PubMed Central

During the past century, fossil fuels—petroleum liquids, natural gas and coal—were the dominant source of world energy production. From 1950 to 2005, fossil fuels provided 85–93% of all energy production. All fossil fuels grew substantially during this period, their combined growth exceeding the increase in world population. This growth, however, was irregular, providing for rapidly growing per capita production from 1950 to 1980, stable per capita production from 1980 to 2000 and rising per capita production again after 2000. During the past half century, growth in fossil fuel production was essentially limited by energy demand. During the next half century, fossil fuel production will be limited primarily by the amount and characteristics of remaining fossil fuel resources. Three possible scenarios—low, medium and high—are developed for the production of each of the fossil fuels to 2050. These scenarios differ primarily by the amount of ultimate resources estimated for each fossil fuel. Total fossil fuel production will continue to grow, but only slowly for the next 15–30 years. The subsequent peak plateau will last for 10–15 years. These production peaks are robust; none of the fossil fuels, even with highly optimistic resource estimates, is projected to keep growing beyond 2050. World fossil fuel production per capita will thus begin an irreversible decline between 2020 and 2030.

Nehring, Richard

2009-01-01

380

Aestivation in the fossil record: evidence from ichnology.  

PubMed

Aestivation is a physiological and behavioral response to high temperature or low moisture conditions. Therefore, it is typically not considered to be capable of being preserved in the fossil record. However, most aestivating organisms produce a burrow to protect themselves from the harmful environmental conditions that trigger aestivation. These structures can be preserved in the rock record as trace fossils. While trace fossils are abundant in the continental fossil record, few are definitively associated with aestivation. Interpreting aestivation behavior from fossil burrows requires a detailed examination and interpretation of the surrounding sedimentary rocks and comparisons with taxonomically and ecologically similar extant organisms. Currently, only four types of aestivation structures are recognized in the fossil record: Pleistocene earthworm chambers, Devonian to Cretaceous lungfish burrows, Permian lysorophid burrows, and Permian to Triassic dicynodont burrows. The trace fossil evidence suggests that aestivation evolved independently among continental organisms in several clades during the middle to late Paleozoic. PMID:20069413

Hembree, Daniel I

2010-01-01

381

Fossil Energy Program semiannual progress report, October 1990--March 1991  

SciTech Connect

This report covers progress made during the period October 1, 1990, through March 31, 1991, for research and development projects that contribute to the advancement of various fossil energy technologies. Projects on the Fossil Energy Program are supported by the DOE Office of Fossil Energy, the DOE Morgantown Energy Technology Center, the DOE Pittsburgh Energy Technology Center, the DOE Fossil Energy Clean Coal Technology Program, the DOE Office of Basic Energy Sciences, the DOE Fossil Energy Office of Petroleum Reserves, the DOE Fossil Energy Naval Petroleum and Oil Shale Reserves, and the US Agency for International Development. The Fossil, Energy Program organization chart is shown in the appendix. Topics include: alloys, ceramics and composite research and development; corrosion and erosion research; environmental analysis and information systems; coal conversion development; mild gasification product characterization; coal combustion research; strategic petroleum reserve planning and modeling; and coal structure and chemistry.

Judkins, R.R.

1992-07-01

382

Azole affinity of sterol 14?-demethylase (CYP51) enzymes from Candida albicans and Homo sapiens.  

PubMed

Candida albicans CYP51 (CaCYP51) (Erg11), full-length Homo sapiens CYP51 (HsCYP51), and truncated ?60HsCYP51 were expressed in Escherichia coli and purified to homogeneity. CaCYP51 and both HsCYP51 enzymes bound lanosterol (K(s), 14 to 18 ?M) and catalyzed the 14?-demethylation of lanosterol using Homo sapiens cytochrome P450 reductase and NADPH as redox partners. Both HsCYP51 enzymes bound clotrimazole, itraconazole, and ketoconazole tightly (dissociation constants [K(d)s], 42 to 131 nM) but bound fluconazole (K(d), ~30,500 nM) and voriconazole (K(d), ~2,300 nM) weakly, whereas CaCYP51 bound all five medical azole drugs tightly (K(d)s, 10 to 56 nM). Selectivity for CaCYP51 over HsCYP51 ranged from 2-fold (clotrimazole) to 540-fold (fluconazole) among the medical azoles. In contrast, selectivity for CaCYP51 over ?60HsCYP51 with agricultural azoles ranged from 3-fold (tebuconazole) to 9-fold (propiconazole). Prothioconazole bound extremely weakly to CaCYP51 and ?60HsCYP51, producing atypical type I UV-visible difference spectra (K(d)s, 6,100 and 910 nM, respectively), indicating that binding was not accomplished through direct coordination with the heme ferric ion. Prothioconazole-desthio (the intracellular derivative of prothioconazole) bound tightly to both CaCYP51 and ?60HsCYP51 (K(d), ~40 nM). These differences in binding affinities were reflected in the observed 50% inhibitory concentration (IC(50)) values, which were 9- to 2,000-fold higher for ?60HsCYP51 than for CaCYP51, with the exception of tebuconazole, which strongly inhibited both CYP51 enzymes. In contrast, prothioconazole weakly inhibited CaCYP51 (IC(50), ~150 ?M) and did not significantly inhibit ?60HsCYP51. PMID:23274672

Warrilow, Andrew G; Parker, Josie E; Kelly, Diane E; Kelly, Steven L

2013-03-01

383

Comparative evaluation of solar, fission, fusion, and fossil energy resources. Part 4: Energy from fossil fuels  

NASA Technical Reports Server (NTRS)

The conversion of fossil-fired power plants now burning oil or gas to burn coal is discussed along with the relaxation of air quality standards and the development of coal gasification processes to insure a continued supply of gas from coal. The location of oil fields, refining areas, natural gas fields, and pipelines in the U.S. is shown. The technologies of modern fossil-fired boilers and gas turbines are defined along with the new technologies of fluid-bed boilers and MHD generators.

Williams, J. R.

1974-01-01

384

The place of Neandertals in the evolution of hominid patterns of growth and development  

Microsoft Academic Search

This study uses the two developmental fields of dental maturation and femoral growth to determine if the pattern of growth and development in Neandertals (archaic Homo sapiens) was intermediate between that of Homo erectus and recent modern humans. Specimens used in the analysis included Neandertals and Upper Palaeolithic early modernHomo sapiens from Europe and individuals from two recent modern human

Jennifer L. Thompson; Andrew J. Nelson

2000-01-01

385

The youngest Ediacaran fossils from southern Africa.  

PubMed

Discovery of fossils of the Ediacara biota near the top of the Spitzkopf Member at farm Swanpunt extends the known range of these remains in Namibia more than 600 m to near the sub-Cambrian unconformity. The fossiliferous beds occur approximately 100 m above a volcanic ash dated at 543 +/- 1 Ma, and thus may be the youngest Proterozoic Ediacara-type fossils reported anywhere in the world. Fossils are preserved within and on the tops of dm-thick beds of storm-deposited sandstone at two stratigraphic levels; the environment is interpreted as open marine, generally calm but with episodic disruptions by storm waves, and probably within the euphotic zone. The presence of Pteridinium carolinaense (St. Jean), which is also known from the classic sections in Ediacara and the White Sea among others, reinforces evidence from geochronology and chemostratigraphy that the Swartpunt section is terminal Neoproterozoic in age. The new genus and species Swartpuntia germsi is a large, multifoliate frond that exhibits at least three quilted petaloids. Macroscopically, Swartpuntia resembles Pteridinium and Ediacara-type fronds such as Charniodiscus traditionally interpreted as Cnidaria, whereas microscopically it exhibits segmentation that is remarkably similar to that of the putative worm Dickinsonia. Combination of diagnostic characters of these supposedly disparate groups in a single species suggests that many species of quilted Ediacaran organisms were more similar to each other than they were to any modern groups, and provides support for the concept of the "Vendobionta" as a late Neoproterozoic group of mainly multifoliate organisms with a distinctive quilted segmentation. PMID:11541433

Narbonne, G M; Saylor, B Z; Grotzinger, J P

1997-11-01

386

Forests in a fossil-fuel world  

SciTech Connect

Humanity's use of the fossilized remains of ancient forests now threatens the health and productivity of the modern-day descendants of these trees. Air pollution and acid rain are attacking forests around the world, threatening ecological disaster unless action is taken. Weakened by the stress of air pollutants, acidic and impoverished soils, or toxic metals, trees lose their resistance to natural events such as drought, insect attacks, and frost. Although the mechanisms of this damage are not understood, a growing body of circumstantial evidence is unfolding in North America and in the forests of West Germany. International cooperation and government recognition that prices must include the cost of pollution damage are essential.

Postel, S.

1984-08-01

387

What Can You Learn From Fossils?  

NSDL National Science Digital Library

At one point or another, it seems like all students are interested in paleontology. Wonderful extinct animals like dinosaurs excite the imagination like almost nothing else. Once you have the students' interest, you will find that a study of paleontology provides avenues of exploration into a wide variety of foundational sciences such as biology, geology, chemistry, physics, and astronomy. The purpose of this set of activities is to enable students to engage in the same kind of investigative study as do paleontologists. Included in this free selection from Adventures in Paleontology: 36 Classroom Fossil Activities are nine lessons and corresponding activities. You will also find included, a Table of Contents, Introduction, and Index.

Slesnick, Irwin; Hansen, Thor

2006-01-01

388

After the Bell: Beachcombing for fossils  

NSDL National Science Digital Library

If you have ever taken a field trip to a natural history museum or an aquarium, you may have noticed in the gift shop a display of fossil shark teeth that can be as old as 65 million years for sale. Where did these teeth come from? How are the ages of these teeth known? Can I find such teeth on my own and, if so, where? These are questions that people of all ages often ask while marveling at these beautiful relics from eons past, and these are the questions we answer in this month's After the Bell column.

Craven, John; Hogan, Tracy

2006-10-01

389

Recent Developments in Biodesulfurization of Fossil Fuels  

NASA Astrophysics Data System (ADS)

The emission of sulfur oxides can have adverse effects on the environment. Biodesulfurization of fossil fuels is attracting more and more attention because such a bioprocess is environmentally friendly. Some techniques of desulfurization have been used or studied to meet the stricter limitation on sulfur content in China. Recent advances have demonstrated the mechanism and developments for biodesulfurization of gasoline, diesel and crude oils by free cells or immobilized cells. Genetic technology was also used to improve sulfur removal efficiencies. In this review, we summarize recent progress mainly in China on petroleum biodesulfurization.

Xu, Ping; Feng, Jinhui; Yu, Bo; Li, Fuli; Ma, Cuiqing

390

Automated evaluation of angiogenic effects mediated by VEGF and PlGF homo- and heterodimers.  

PubMed

The effects of growth factors on the blood vessel pattern of chick chorioallantoic membrane (CAM) were assessed with a fast and automated method (extended counting method, XCM; Sandau, 1996) that measures complexity, without assumptions about a fractal structure. XCM is a reliable measure of complexity not only in theory but also in practice: (1) it is robust with respect to thresholding; (2) it shows reduced variance due to pattern translation and rotation; (3) its properties come close to requirements of fractal geometry. It hence is superior to established fractal methods for distinguishing effects induced by various isoforms of vascular endothelial growth factor (VEGF121 and VEGF165), placenta growth factor (PlGF) isoforms, and control treatment. We here show that VEGF homo- and heterodimers and VEGF121/PlGF1 heterodimers increase vascular complexity, whereas PlGF1 and PlGF2 are not effective. PlGF1 and VEGF121 did not mutually influence each other when applied in adjacent fields on the same CAM. Since blood vessels in the CAM originate via nonfractal growth processes, their growth should be analyzed accordingly. PMID:9473412

Kurz, H; Wilting, J; Sandau, K; Christ, B

1998-01-01

391

Homo-FRET Imaging Enables Quantification of Protein Cluster Sizes with Subcellular Resolution  

PubMed Central

Fluorescence-anisotropy-based homo-FRET detection methods can be employed to study clustering of identical proteins in cells. Here, the potential of fluorescence anisotropy microscopy for the quantitative imaging of protein clusters with subcellular resolution is investigated. Steady-state and time-resolved anisotropy detection and both one- and two-photon excitation methods are compared. The methods are evaluated on cells expressing green fluorescent protein (GFP) constructs that contain one or two FK506-binding proteins. This makes it possible to control dimerization and oligomerization of the constructs and yields the experimental relation between anisotropy and cluster size. The results show that, independent of the experimental method, the commonly made assumption of complete depolarization after a single energy transfer step is not valid here. This is due to a nonrandom relative orientation of the fluorescent proteins. Our experiments show that this relative orientation is restricted by interactions between the GFP barrels. We describe how the experimental relation between anisotropy and cluster size can be employed in quantitative cluster size imaging experiments of other GFP fusions. Experiments on glycosylphosphatidylinisotol (GPI)-anchored proteins reveal that GPI forms clusters with an average size of more than two subunits. For epidermal growth factor receptor (EGFR), we observe that ?40% of the unstimulated receptors are present in the plasma membrane as preexisting dimers. Both examples reveal subcellular heterogeneities in cluster size and distribution.

Bader, Arjen N.; Hofman, Erik G.; Voortman, Jarno; van Bergen en Henegouwen, Paul M.P.; Gerritsen, Hans C.

2009-01-01

392

erbB3 is an active tyrosine kinase capable of homo- and heterointeractions.  

PubMed

Often considered to be a "dead" kinase, erbB3 is implicated in escape from erbB-targeted cancer therapies. Here, heregulin stimulation is shown to markedly upregulate kinase activity in erbB3 immunoprecipitates. Intact, activated erbB3 phosphorylates tyrosine sites in an exogenous peptide substrate, and this activity is abolished by mutagenesis of lysine 723 in the catalytic domain. Enhanced erbB3 kinase activity is linked to heterointeractions with catalytically active erbB2, since it is largely blocked in cells pretreated with lapatinib or pertuzumab. erbB2 activation of erbB3 is not dependent on equal surface levels of these receptors, since it occurs even in erbB3-transfected CHO cells with disproportionally small amounts of erbB2. We tested a model in which transient erbB3/erbB2 heterointeractions set the stage for erbB3 homodimers to be signaling competent. erbB3 homo- and heterodimerization events were captured in real time on live cells using single-particle tracking of quantum dot probes bound to ligand or hemagglutinin tags on recombinant receptors. PMID:24379439

Steinkamp, Mara P; Low-Nam, Shalini T; Yang, Shujie; Lidke, Keith A; Lidke, Diane S; Wilson, Bridget S

2014-03-01

393

Simulation of Threading Dislocation Images in X-ray Topographs of Silicon Carbide Homo-Epilayers  

SciTech Connect

Three types of dislocation are seen in homo-epilayers of SiC grown on 4H-SiC wafers with an 8 degree surface offcut: axial screw dislocations, basal plane dislocations propagated into the epilayer at an 8 degree inclination and threading edge dislocations. These types may be imaged by monochromatic synchrotron X-ray topography in the grazing-incidence reflection geometry using the 11{bar 2}8 reflection. Equations needed to apply the ray-tracing method of computer simulating X-ray topographic defect images in this experimental geometry were derived and used to simulate images of all three. Simulations for axial screw dislocations appear as white circles surrounded by narrow dark rings, and those for basal plane dislocations as linear white streaks, both consistent with experimental topographs. Simulations of the threading edge dislocations showed 4 {micro}m wide white ovals with narrow arcs of dark contrast at their ends, inclined relative to the g vector of the topograph according to the sign of their Burgers vector. These images resembled the experimental topographs inasmuch as was possible at the maximum resolution of X-ray topographs.

Vetter,W.; Tsuchida, H.; Kamata, I.; Dudley, M.

2005-01-01

394

Indium oxide thin-film homo-junctions: Morphology and electrical properties  

NASA Astrophysics Data System (ADS)

Indium oxide shows an unusual combination of electrical and optical properties that give rise to a broad range of applications in optoelectronic devices. Here, we report results of structural, x-ray photoelectron spectroscopy, and electrical transport studies of transparent homo-junctions, obtained by sequential growth of polycrystalline thin layers of indium oxide under O2-rich and O2-poor conditions. We find that the growth temperature, which affects significantly film morphology, is critical for the rectifying behavior of the junctions. Only junctions grown at about 350 °C are rectifying. We also find that p-type-like layers have higher concentration of inter-grain oxygen than n-type layers, presumably coming from oxygen-rich deposition conditions and from much larger number of grain boundaries than in n-type layers. We conjecture that the segregation of oxygen ions at grain boundaries is responsible for the formation of inversion layers in O2-rich films and their apparent p-type dc conduction. This mechanism significantly modifies the capacitance-voltage characteristics of the junctions. However, the rectifying mechanism can be accounted for by a space-charge layer at the p-n interface. Such behavior might be important in other polycrystalline thin films with a large number of interface defects at grain boundaries.

Stankiewicz, Jolanta; Villuendas, Francisco; Pilar Lozano, María; Díez, Isabel

2013-08-01

395

Calix[n]imidazolium as a new class of positively charged homo-calix compounds  

PubMed Central

Macrocycles based on neutral calixarenes and calixpyrroles have been extensively explored for ion binding, molecular assembly and related applications. Given that only these two types of calix compounds and their analogs are available, the introduction of new forms of widely usable calix macrocycles is an outstanding challenge. Here we report the quadruply/quintuply charged imidazole-based homo-calix compounds, calix[4/5]imidazolium. The noncovalent (C-H)+/?+-anion interactions of the imidazolium rings with anions inside and outside the cone are the stabilizing factors for crystal packing, resulting in self-assembled arrays of cone-shaped calix-imidazolium molecules. Calix[4]imidazolium senses fluoride selectively even in aqueous solutions. Calix[5]imidazolium recognizes neutral fullerenes through ?+–? interactions and makes them soluble in water, which could be useful in fullerene chemistry. Not only derivatization and ring expansion of calix[n]imidazolium, but also their utilization in ionic liquids, carbene chemistry and nanographite/graphene exfoliation could be exploited.

Chun, Young; Jiten Singh, N; Hwang, In-Chul; Woo Lee, Jung; Yu, Seong Uk; Kim, Kwang S

2013-01-01

396

Glycosyl Modification Facilitates Homo- and Hetero-oligomerization of the Serotonin Transporter  

PubMed Central

The serotonin transporter (SERT) is an oligomeric glycoprotein with two sialic acid residues on each of two complex oligosaccharide molecules. In this study, we investigated the contribution of N-glycosyl modification to the structure and function of SERT in two model systems: wild-type SERT expressed in sialic acid-defective Lec Chinese hamster ovary (CHO) cells and a mutant form (after site-directed mutagenesis of Asn-208 and Asn-217 to Gln) of SERT, QQ, expressed in parental CHO cells. In both systems, SERT monomers required modification with both complex oligosaccharide residues to associate with each other and to function in homo-oligomeric forms. However, defects in sialylated N-glycans did not alter surface expression of the SERT protein. Furthermore, in heterologous (CHO and Lec) and endogenous (placental choriocarcinoma JAR cells) expression systems, we tested whether glycosyl modification also manipulates the hetero-oligomeric interactions of SERT, specifically with myosin IIA. SERT is phosphorylated by cGMP-dependent protein kinase G through interactions with anchoring proteins, and myosin is a protein kinase G-anchoring protein. A physical interaction between myosin and SERT was apparent; however, defects in sialylated N-glycans impaired association of SERT with myosin as well as the stimulation of the serotonin uptake function in the cGMP-dependent pathway. We propose that sialylated N-glycans provide a favorable conformation to SERT that allows the transporter to function most efficiently via its protein-protein interactions.

Ozaslan, Deniz; Wang, Sophie; Ahmed, Billow A.; Kocabas, Arif M.; McCastlain, John C.; Bene, Anca; Kilic, Fusun

2011-01-01

397

The critical role played by animal source foods in human (Homo) evolution.  

PubMed

Wild primates take most of the daily diet from plant sources, eating moderate to small amounts of animal source foods (ASF). Plant materials make up from 87% to >99% of the annual diet of great apes, the closest living relatives of modern humans (Homo sapiens sapiens). Reflecting their close genetic relationship, gut form and nutrient requirements of apes and humans (Hominoidea) are very similar, as is their pattern of digestive kinetics-one predicated on a relatively slow turnover of ingesta. In plant-eating mammals, in contrast to carnivorous mammals, greater body size is associated with lower dietary quality. Turning to ASF as a routine rather than occasional dietary component would have permitted the evolving human lineage to evade the nutritional constraints placed on body size increases in apes. Without routine access to ASF, it is highly unlikely that evolving humans could have achieved their unusually large and complex brain while simultaneously continuing their evolutionary trajectory as large, active and highly social primates. As human evolution progressed, young children in particular, with their rapidly expanding large brain and high metabolic and nutritional demands relative to adults would have benefited from volumetrically concentrated, high quality foods such as meat. Today, many humans, particularly those in high income nations, have a variety of high quality, non-ASF dietary alternatives, but such foods were not generally available to paleolithic human ancestors nor to many people today in low income nations. PMID:14672286

Milton, Katharine

2003-11-01

398

Novel Telechelic Polymer Hydrogels using Homo and Hetero-combinations of End-blocks  

NASA Astrophysics Data System (ADS)

The last two decades have seen telechelic triblock polymers support increasing number of applications as stabilizers and flow modifiers in fields as varied as pharmaceutics, paints and oil recovery. Mainly consisting of a solvophilic mid-block end-capped with solvophobic blocks, their use as flow altering additives stems from their ability to form gels comprising hydrophobic junctions, with hydrophilic blocks bridging these junctions. Previous studies have shown that the chemical nature of the end-block has a direct bearing on the morphology of the gel, which in turn affects its macroscopic properties. We have conducted an examination of this relationship using a variety of techniques including cryogenic scanning electron microscopy (cryo-SEM), small angle neutron scattering (SANS) and rheology. Using homo and hetero-combinations of poly(1,2-butadiene) and poly(perfluoropropylene oxide) as hydrophobic end-blocks with poly(ethylene oxide) as the hydrophilic mid-block, we have demonstrated that the hydrogels obtained are distinct in morphology and physical properties. The study seeks to highlight the importance of controlling end-blocks in triblock polymers as a potential tool towards manipulating the physical properties of gels.

Taribagil, Rajiv R.; Hillmyer, Marc A.; Lodge, Timothy P.

2010-03-01

399

Regulation of the transcription factor Ets-1 by DNA-mediated homo-dimerization  

PubMed Central

The function of the Ets-1 transcription factor is regulated by two regions that flank its DNA-binding domain. A previously established mechanism for auto-inhibition of monomeric Ets-1 on DNA response elements with a single ETS-binding site, however, has not been observed for the stromelysin-1 promoter containing two palindromic ETS-binding sites. We present the structure of Ets-1 on this promoter element, revealing a ternary complex in which protein homo-dimerization is mediated by the specific arrangement of the two ETS-binding sites. In this complex, the N-terminal-flanking region is required for ternary protein–DNA assembly. Ets-1 variants, in which residues from this region are mutated, loose the ability for DNA-mediated dimerization and stromelysin-1 promoter transactivation. Thus, our data unravel the molecular basis for relief of auto-inhibition and the ability of Ets-1 to function as a facultative dimeric transcription factor on this site. Our findings may also explain previous data of Ets-1 function in the context of heterologous transcription factors, thus providing a molecular model that could also be valid for Ets-1 regulation by hetero-oligomeric assembly.

Lamber, Ekaterina P; Vanhille, Laurent; Textor, Larissa C; Kachalova, Galina S; Sieweke, Michael H; Wilmanns, Matthias

2008-01-01

400

Homo-oligomerisation and nuclear localisation of mouse histone deacetylase 1.  

PubMed

Reversible histone acetylation changes the chromatin structure and can modulate gene transcription. Mammalian histone deacetylase 1 (HDAC1) is a nuclear protein that belongs to a growing family of evolutionarily conserved enzymes catalysing the removal of acetyl residues from core histones and other proteins. Previously, we have identified murine HDAC1 as a growth factor-inducible protein in murine T-cells. Here, we characterise the molecular function of mouse HDAC1 in more detail. Co-immunoprecipitation experiments with epitope-tagged HDAC1 protein reveal the association with endogenous HDAC1 enzyme. We show that HDAC1 can homo-oligomerise and that this interaction is dependent on the N-terminal HDAC association domain of the protein. Furthermore, the same HDAC1 domain is also necessary for in vitro binding of HDAC2 and HDAC3, association with RbAp48 and for catalytic activity of the enzyme. A lysine-rich sequence within the carboxy terminus of HDAC1 is crucial for nuclear localisation of the enzyme. We identify a C-terminal nuclear localisation domain, which is sufficient for the transport of HDAC1 and of reporter fusion proteins into the nucleus. Alternatively, HDAC1 can be shuttled into the nucleus by association with another HDAC1 molecule via its N-terminal HDAC association domain. Our results define two domains, which are essential for the oligomerisation and nuclear localisation of mouse HDAC1. PMID:11302704

Taplick, J; Kurtev, V; Kroboth, K; Posch, M; Lechner, T; Seiser, C

2001-04-20

401

Homo- and heterofermentative lactobacilli differently affect sugarcane-based fuel ethanol fermentation.  

PubMed

Bacterial contamination during industrial yeast fermentation has serious economic consequences for fuel ethanol producers. In addition to deviating carbon away from ethanol formation, bacterial cells and their metabolites often have a detrimental effect on yeast fermentative performance. The bacterial contaminants are commonly lactic acid bacteria (LAB), comprising both homo- and heterofermentative strains. We have studied the effects of these two different types of bacteria upon yeast fermentative performance, particularly in connection with sugarcane-based fuel ethanol fermentation process. Homofermentative Lactobacillus plantarum was found to be more detrimental to an industrial yeast strain (Saccharomyces cerevisiae CAT-1), when compared with heterofermentative Lactobacillus fermentum, in terms of reduced yeast viability and ethanol formation, presumably due to the higher titres of lactic acid in the growth medium. These effects were only noticed when bacteria and yeast were inoculated in equal cell numbers. However, when simulating industrial fuel ethanol conditions, as conducted in Brazil where high yeast cell densities and short fermentation time prevail, the heterofermentative strain was more deleterious than the homofermentative type, causing lower ethanol yield and out competing yeast cells during cell recycle. Yeast overproduction of glycerol was noticed only in the presence of the heterofermentative bacterium. Since the heterofermentative bacterium was shown to be more deleterious to yeast cells than the homofermentative strain, we believe our findings could stimulate the search for more strain-specific antimicrobial agents to treat bacterial contaminations during industrial ethanol fermentation. PMID:24198118

Basso, Thiago Olitta; Gomes, Fernanda Sgarbosa; Lopes, Mario Lucio; de Amorim, Henrique Vianna; Eggleston, Gillian; Basso, Luiz Carlos

2014-01-01

402

Earth's early fossil record: Why not look for similar fossils on Mars?  

NASA Technical Reports Server (NTRS)

The oldest evidence of life on Earth is discussed with attention being given to the structure and formation of stromatolites and microfossils. Fossilization of microbes in calcium carbonate or chert media is discussed. In searching for fossil remains on Mars, some lessons learned from the study of Earth's earliest fossil record can be applied. Certain sedimentary rock types and sedimentary rock configurations should be targeted for investigation and returned by the Martian rover and ultimately by human explorers. Domical, columnar to wavy laminated stratiform sedimentary rocks that resemble stromatolites should be actively sought. Limestone, other carbonates, and chert are the favored lithology. Being macroscopic, stromatolites might be recognized by an intelligent unmanned rover. In addition, black, waxy chert with conchoidal fracture should be sought. Chert is by far the preferred lithology for the preservation of microbes and chemical fossils. Even under optimal geological conditions (little or no metamorphism or tectonic alteration, excellent outcrops, and good black chert) and using experienced field biogeologists, the chances of finding well preserved microbial remains in chert are very low.

Awramik, Stanley M.

1989-01-01

403

Taxonomy and fossils: a critical appraisal.  

PubMed Central

Many compendia at the species, genus and family levels document the fossil record, but these are not standardized, nor usually critical in content, and few are available on the World Wide Web. The sampling of the available record is good for organisms with fossilizable parts, but preservational constraints on the entire morphology, life history and geographical distribution lead to difficulties in recognizing and naming species. We recommend abandoning some of the palaeontological species concepts such as chronospecies and stratospecies, and we advocate species recognition based on unique combinations of characters. The compilation of species lists is extremely time consuming, and given the inherent problems we suggest that compilation of generic lists is a more achievable goal because genera are recognized by definitive morphological characters. In calculating taxon duration, care must be taken to distinguish between mono-, para- and polyphyletic groups, the first being the only reliable unit for use in calculating diversity curves. We support the inclusion of fossils into classifications based on Recent organisms, but we recognize some of the problems this may pose for standard Linnaean classifications. Web-based taxonomy is the way forward, having the advantages of speed and currency of information dissemination, universal access with links to primary literature and increasingly sophisticated imagery. These advantages over conventional outlets will only be realized with careful Web design and a commitment to maintenance.

Forey, Peter L; Fortey, Richard A; Kenrick, Paul; Smith, Andrew B

2004-01-01

404

Shotgun microbial profiling of fossil remains.  

PubMed

Millions to billions of DNA sequences can now be generated from ancient skeletal remains thanks to the massive throughput of next-generation sequencing platforms. Except in cases of exceptional endogenous DNA preservation, most of the sequences isolated from fossil material do not originate from the specimen of interest, but instead reflect environmental organisms that colonized the specimen after death. Here, we characterize the microbial diversity recovered from seven c. 200- to 13 000-year-old horse bones collected from northern Siberia. We use a robust, taxonomy-based assignment approach to identify the microorganisms present in ancient DNA extracts and quantify their relative abundance. Our results suggest that molecular preservation niches exist within ancient samples that can potentially be used to characterize the environments from which the remains are recovered. In addition, microbial community profiling of the seven specimens revealed site-specific environmental signatures. These microbial communities appear to comprise mainly organisms that colonized the fossils recently. Our approach significantly extends the amount of useful data that can be recovered from ancient specimens using a shotgun sequencing approach. In future, it may be possible to correlate, for example, the accumulation of postmortem DNA damage with the presence and/or abundance of particular microbes. PMID:24612293

Der Sarkissian, C; Ermini, L; Jónsson, H; Alekseev, A N; Crubezy, E; Shapiro, B; Orlando, L

2014-04-01

405

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

406

Fossil energy biotechnology: A research needs assessment. Final report  

SciTech Connect

The Office of Program Analysis of the US Department of Energy commissioned this study to evaluate and prioritize research needs in fossil energy biotechnology. The objectives were to identify research initiatives in biotechnology that offer timely and strategic options for the more efficient and effective uses of the Nation`s fossil resource base, particularly the early identification of new and novel applications of biotechnology for the use or conversion of domestic fossil fuels. Fossil energy biotechnology consists of a number of diverse and distinct technologies, all related by the common denominator -- biocatalysis. The expert panel organized 14 technical subjects into three interrelated biotechnology programs: (1) upgrading the fuel value of fossil fuels; (2) bioconversion of fossil feedstocks and refined products to added value chemicals; and, (3) the development of environmental management strategies to minimize and mitigate the release of toxic and hazardous petrochemical wastes.

Not Available

1993-11-01

407

A report on biocompounds from palm fossil of India  

PubMed Central

The occurrence of a large number of fossil woods having resemblance in anatomical features with the modern palm genus, Phoenix L in Deccan Intertrappean fossil flora of Maastrichtian-Danian age (i. e. Late Cretaceous and Earliest Tertiary (65-67 my)) indicates the most primitive record of date palm. Present discovery of biocompounds from fossil wood of Phoenix collected from Deccan Intertrappean having affinity with the biocompounds known from modern plant further exemplify the earliest documentation of Phoenix in Indian peninsula.

Sharma, Dinesh Chandra; Khan, Mohd Sajid; Khan, M Salman; Srivastava, Rashmi; Srivastava, Ashwini Kumar; Shukla, Ritu

2014-01-01

408

THE FOSSIL HISTORY OF THE LEGUMINOSAE: PHYLOGENETIC AND BIOGEOGRAPHIC IMPLICATIONS  

Microsoft Academic Search

his paper summarizes the lileralure dealing with systematic and biogeographic as~eLls orlhe fossil record oflhe ugllmLnosae II addresses the implications oflhe fossil recon.! wil h respecl to i) structural evolution within the family, ii) pattern and timing of lhvers,licallon in Ihe Lcguminosae, iii) biogeographic history, and iv) cU!Tent.hypotheses of phylogenelic relauonships within the family. The early fossil record of the

PATRICK S HERENDEEN; WILLIAM L CREPET; DAVID L DILCHER

409

Side-chain liquid crystalline homo- and copolymethacrylates with a carbonate linkage between the benzylideneaniline mesogen and ethylene chain  

Microsoft Academic Search

New liquid crystalline (LC) homo- and copolymethacrylates having a carbonate linkage between a benzylideneaniline mesogen and ethylene chain in the side chain were prepared by free radical polymerization of methacrylate derivatives comprising 4-cyano- and\\/or 4-methoxybenzylide-neaniline units using AIBN as an initiator. The structures of the polymers were characterized by FTIR, HNMR, and elemental analyses. The LC properties were evaluated by

Moriyuki Sato; Takashi Nakano; Ken-Ichi Mukaida

1995-01-01

410

Melt complex viscosity and molecular weights for homo-polypropylene modified by grafting bifunctional monomers under electron beam irradiation  

Microsoft Academic Search

High melt viscosity polypropylene was manufactured by grafting bifunctional monomers, HDDA (1,6-hexanediol diacrylate) and TPGDA (tripropyleneglycol diacrylate), onto homo-polypropylene under an electron beam irradiation. Melt complex viscosity (??) of modified polypropylene was sensitive to irradiation dose and monomer content. The melt viscosity of the polypropylene modified with TPGDA increased to 132,290Pas (at 190°C and 0.1rad\\/s of frequency) from 5039Pas for

Do-Hung Han; Jae-Hyuk Jang; Byung-Gi Cho; Byung-Nam Kim; Gil-Soo Seo

2006-01-01

411

Synthesis, characterization, catalase functions and DNA cleavage studies of new homo and heteronuclear Schiff base copper(II) complexes  

Microsoft Academic Search

A new tetradentate diimine–dioxime ligand containing a donor set of N4, and its homo-, heterodinuclear and homotrinuclear copper(II) complexes were prepared and characterized on the basis of their elemental analysis, FT-IR, 1H and 13C NMR spectra, molar conductivity and magnetic moment measurements. The extraction ability of N,N??-bis[1-biphenyl-2-hydroxyimino-1-ethylidene]-diethylenetriamine was also evaluated in chloroform by using several transition metal picrates such as

Bulent Dede; Ismail Ozmen; Fatma Karipcin

2009-01-01

412

The upstream conserved regions (UCRs) mediate homo- and hetero-oligomerization of type 4 cyclic nucleotide phosphodiesterases (PDE4s).  

PubMed

PDE4s (type 4 cyclic nucleotide phosphodiesterases) are divided into long and short forms by the presence or absence of conserved N-terminal domains termed UCRs (upstream conserved regions). We have shown previously that PDE4D2, a short variant, is a monomer, whereas PDE4D3, a long variant, is a dimer. In the present study, we have determined the apparent molecular masses of various long and short PDE4 variants by size-exclusion chromatography and sucrose density-gradient centrifugation. Our results indicate that dimerization is a conserved property of all long PDE4 forms, whereas short forms are monomers. Dimerization is mediated by the UCR domains. Given their high sequence conservation, the UCR domains mediate not only homo-oligomerization, but also hetero-oligomerization of distinct PDE4 long forms as detected by co-immunoprecipitation assays and FRET microscopy. Endogenous PDE4 hetero-oligomers are, however, low in abundance compared with homo-dimers, revealing the presence of mechanisms that predispose PDE4s towards homo-oligomerization. Oligomerization is a prerequisite for the regulatory properties of the PDE4 long forms, such as their PKA (protein kinase A)-dependent activation, but is not necessary for PDE4 protein-protein interactions. As a result, individual PDE4 protomers may independently mediate protein-protein interactions, providing a mechanism whereby PDE4s contribute to the assembly of macromolecular signalling complexes. PMID:24555506

Xie, Moses; Blackman, Brigitte; Scheitrum, Colleen; Mika, Delphine; Blanchard, Elise; Lei, Tao; Conti, Marco; Richter, Wito

2014-05-01

413

Geometric variation of the frontal squama in the genus homo: frontal bulging and the origin of modern human morphology.  

PubMed

The majority of studies of frontal bone morphology in paleoanthropology have analyzed the frontal squama and the browridge as a single unit, mixing information from different functional elements. Taking into account that the bulging of the frontal bone is often described as a species-specific trait of Homo sapiens, in this article we analyze variation in the midsagittal profile of the genus Homo, focusing on the frontal squama alone, using landmark-based superimpositions and principal components analysis. Our results demonstrate that anatomically modern humans are definitely separated from extinct human taxa on the basis of frontal bulging. However, there is minor overlap among these groups, indicating that it is necessary to exercise caution when using this trait alone to make taxonomic inferences on individual specimens. Early modern humans do not show differences with recent modern humans, and "transitional" individuals such as Jebel Irhoud 1, Maba, and Florisbad, show modern-like frontal squama morphology. The bulging of the frontal squama in modern humans may represent a structural consequence of more general cranial changes, or it could be a response to changes in the morphology of the underlying prefrontal brain elements. A subtle difference between Neandertals and the Afro-European Middle Pleistocene Homo sample is associated with flattening at bregma in the former group, a result that merits further investigation. PMID:23292748

Bruner, Emiliano; Athreya, Sheela; de la Cuétara, José Manuel; Marks, Tarah

2013-02-01

414

Functional inositol 1,4,5-trisphosphate receptors assembled from concatenated homo- and heteromeric subunits.  

PubMed

Vertebrate genomes code for three subtypes of inositol 1,4,5-trisphosphate (IP3) receptors (IP3R1, -2, and -3). Individual IP3R monomers are assembled to form homo- and heterotetrameric channels that mediate Ca(2+) release from intracellular stores. IP3R subtypes are regulated differentially by IP3, Ca(2+), ATP, and various other cellular factors and events. IP3R subtypes are seldom expressed in isolation in individual cell types, and cells often express different complements of IP3R subtypes. When multiple subtypes of IP3R are co-expressed, the subunit composition of channels cannot be specifically defined. Thus, how the subunit composition of heterotetrameric IP3R channels contributes to shaping the spatio-temporal properties of IP3-mediated Ca(2+) signals has been difficult to evaluate. To address this question, we created concatenated IP3R linked by short flexible linkers. Dimeric constructs were expressed in DT40-3KO cells, an IP3R null cell line. The dimeric proteins were localized to membranes, ran as intact dimeric proteins on SDS-PAGE, and migrated as an ?1100-kDa band on blue native gels exactly as wild type IP3R. Importantly, IP3R channels formed from concatenated dimers were fully functional as indicated by agonist-induced Ca(2+) release. Using single channel "on-nucleus" patch clamp, the channels assembled from homodimers were essentially indistinguishable from those formed by the wild type receptor. However, the activity of channels formed from concatenated IP3R1 and IP3R2 heterodimers was dominated by IP3R2 in terms of the characteristics of regulation by ATP. These studies provide the first insight into the regulation of heterotetrameric IP3R of defined composition. Importantly, the results indicate that the properties of these channels are not simply a blend of those of the constituent IP3R monomers. PMID:23955339

Alzayady, Kamil J; Wagner, Larry E; Chandrasekhar, Rahul; Monteagudo, Alina; Godiska, Ronald; Tall, Gregory G; Joseph, Suresh K; Yule, David I

2013-10-11

415

Homo floresiensis and the late Pleistocene environments of eastern Indonesia: defining the nature of the relationship  

NASA Astrophysics Data System (ADS)

Evidence from Liang Bua, a limestone cave on the island of Flores in East Indonesia, provides a unique opportunity to explore the long term relationship between hominins and their environment. Occupation deposits at the site span ˜95 ka and contain abundant stone artefacts, well preserved faunal remains and evidence for an endemic species of hominin: Homo floresiensis. Work at the site included detailed geomorphological and environmental analysis, which has enabled comparisons to be drawn between changes in the occupational intensity in the cave, using stone tool and faunal counts, and changes in the environmental conditions, using the characteristics of the sedimentary layers in the cave and speleothem records. These comparisons demonstrate that H. floresiensis endured rapidly fluctuating environmental conditions over the last ˜100 ka, which influenced the geomorphological processes in the cave and their occupational conditions. The intensity of occupation in the cave changed significantly between 95 and 17 ka, with peaks in occupation occurring at 100-95, 74-61 and 18-17 ka. These correlate with episodes of channel formation and erosion in the cave, which in turn correspond with high rainfall, thick soils and high bio-productivity outside. In contrast, periods of low occupational intensity correlate with reduced channel activity and pooling associated with drier periods from 94 to 75 and 36 to 19 ka. This apparent link between intensity of hominin use of the cave and the general conditions outside relates to the expansion and contraction of the rainforest and the ability of H. floresiensis to adapt to habitat changes. This interpretation implies that these diminutive hominins were able to survive abrupt and prolonged environmental changes by changing their favoured occupation sites. These data provide the basis for a model of human-environment interactions on the island of Flores. With the addition of extra data from other sites on Flores, this model will provide a greater understanding of H. floresiensis as a unique human species.

Westaway, K. E.; Morwood, M. J.; Sutikna, T.; Moore, M. W.; Rokus, A. D.; van den Bergh, G. D.; Roberts, R. G.; Saptomo, E. W.

2009-12-01

416

Structure and spectroscopic studies of homo-and heterometallic complexes of adipic acid dihydrazide  

NASA Astrophysics Data System (ADS)

A single crystal of adipic acid dihydrazide, ADH, has been analyzed. Its reaction with Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+, Ag+, Pd2+ and/or Pt2+ gave homometallic and heterometallic complexes which are characterized by partial elemental analysis, spectra (MS, ESR, 1H NMR, electronic; IR), thermal analysis and magnetic measurements. Some complexes: Zn0.73Cu(ADH)Cl4·H2O; Zn0.71Hg0.36(ADH)Cl4·H2O; Zn0.65Cd0.46(ADH)Cl4·½H2O; Zn0.75Co0.41(ADH-2H)Cl2·3H2O; Cd0.85Co0.43(ADH)Cl4·½EtOH were isolated having nonstiochiometric metal ratios. The ligand behaves as a neutral (bidentate or tetradentate) and/or binegative tetradentate. A square-pyramid, square-planar and tetrahedral structures were proposed for the homo Co(II), Cu(II) and Ni(II) complexes, respectively. A similar and different stereochemistry around each metal ion (tetrahedral + tetrahedral; tetrahedral + square-planar; tetrahedral + tetrahedral and/or tetrahedral + octahedral) was suggested for the heterometallic complexes. Some complexes were found highly stable with stability point >240 °C; the most stable is [HgNi(ADH-2H)Cl2]. The presence of diamagnetic atom (Zn, Cd or Hg) reduces the magnetic moments and gave anomalous moments. The degradation steps and the hydrated complexes are confirmed through the TGA study. The order of covalency of [Zn0.73Cu(ADH)Cl4]·H2O, [CdCu(ADH)Cl4]·H2O and [HgCu(ADH-2H)Cl2] matches with the size of the second metal (Zn complex > Cd complex > Hg complex). Some heterometallic complexes were found nonstoichiometric through the analysis of their metal content and supported by TGA.

Jeragh, Bakir; El-Asmy, Ahmed A.

417

Homo- and heteropolymetallic 3-(2-pyridyl)pyrazolate manganese and rhenium complexes.  

PubMed

fac-[MBr(CO)3(pypzH)] (M = Mn, Re; pypzH = (3-(2-pyridyl)pyrazole) complexes are prepared from fac-[MBr(CO)3(NCMe)2] and pypzH. The result of their deprotonation depends on the metallic substrate: the rhenium complex affords cleanly the bimetallic compound [fac-{Re(CO)3(?(2)-pypz)}]2 (?(2)-pypz = ?(2)-3-(2-pyridyl-?(1)N)pyrazolate-2?(1)N), which was crystallographically characterized, whereas a similar manganese complex was not detected. When two equivalents of pyridylpyrazolate are used, polymetallic species [fac-M(CO)3(?(2)-pypz)(?(3)-pypz)M'] (?(3)-pypz = ?(3)-3-(2-pyridyl-?(1)N)pyrazolate-1?(2)N,N:2?(1)N:; M = Mn, M' = Li, Na, K; M = Re, M' = Na) are obtained. The crystal structures of the manganese carbonylate complexes were determined. The lithium complex is a monomer containing one manganese and one lithium atom, whereas the sodium and potassium complexes are dimers and reveal an unprecedented coordination mode for the bridging 3-(2-pyridyl)pyrazolate ligand, where the nitrogen of the pyridyl fragment and the nitrogen-1 of pyrazolate are chelated to manganese atoms, and each nitrogen-2 of pyrazolate is coordinated to two alkaline atoms. The polymetallic carbonylate complexes are unstable in solution and evolve spontaneously to [fac-{Re(CO)3(?(2)-pypz)}]2 or to the trimetallic paramagnetic species [Mn(II)(?(2)-pypz)2{fac-{Mn(I)(CO)3(?(2)-pypz)}2}]. The related complex cis-[MnCl2(pypzH)2] was also synthesized and structurally characterized. The electrochemical behavior of the new homo- and heteropolymetallic 3-(2-pyridyl)pyrazolate complexes has been studied and details of their redox properties are reported. PMID:24452527

Arroyo, Marta; Gómez-Iglesias, Patricia; Antón, Noelia; García-Rodríguez, Raúl; Alegria, Elisabete C B A; Pombeiro, Armando J L; Miguel, Daniel; Villafañe, Fernando

2014-03-14

418

The future of oil: unconventional fossil fuels.  

PubMed

Unconventional fossil hydrocarbons fall into two categories: resource plays and conversion-sourced hydrocarbons. Resource plays involve the production of accumulations of solid, liquid or gaseous hydro-carbons that have been generated over geological time from organic matter in source rocks. The character of these hydrocarbons may have been modified subsequently, especially in the case of solids and extra-heavy liquids. These unconventional hydrocarbons therefore comprise accumulations of hydrocarbons that are trapped in an unconventional manner and/or whose economic exploitation requires complex and technically advanced production methods. This review focuses primarily on unconventional liquid hydro-carbons. The future potential of unconventional gas, especially shale gas, is also discussed, as it is revolutionizing the energy outlook in North America and elsewhere. PMID:24298078

Chew, Kenneth J

2014-01-13

419

Rates of speciation in the fossil record.  

PubMed Central

Data from palaeontology and biodiversity suggest that the global biota should produce an average of three new species per year. However, the fossil record shows large variation around this mean. Rates of origination have declined through the Phanerozoic. This appears to have been largely a function of sorting among higher taxa (especially classes), which exhibit characteristic rates of speciation (and extinction) that differ among them by nearly an order of magnitude. Secular decline of origination rates is hardly constant, however; many positive deviations reflect accelerated speciation during rebounds from mass extinctions. There has also been general decline in rates of speciation within major taxa through their histories, although rates have tended to remain higher among members in tropical regions. Finally, pulses of speciation appear sometimes to be associated with climate change, although moderate oscillations of climate do not necessarily promote speciation despite forcing changes in species' geographical ranges.

Sepkoski, J J

1998-01-01

420

What Can We Learn From Fossils  

NSDL National Science Digital Library

Students have learned throughout the course how paleontologists make interpretations about fossils. As we covered the various dinosaur groups we covered what interpretations have been made about their growth rates, eating habits, speeds, and etc. There is also a discussion of how paleontologists have made these interpretations. This activity is associated with the Taphonomy chapter and allows students to use the tools that they have acquired throughout the course to make interpretation about a modern animal and an extinct animal. Each student receives a packet of information on a modern animal and an extinct animal. This packet includes various pictures of the skeleton, foot prints, teeth, skull, and etc. To complete the assignment each student must synthesize the knowledge they learned throughout the course and make supported conclusions about each animal. They also must complete a write up of the locality of the extinct animal and what is known about the paleoecology.

Hochstein, Joann

421

Fossil birds of the Kibish Formation.  

PubMed

The Kibish Formation has yielded a small collection of bird fossils, which are identified here as belonging to five species in four different families: Pelecanidae (pelicans), Anhingidae (darters), Ardeidae (herons) and Phasianidae (gamefowl). Two species of pelicans are identified: Pelecanus cf. P. onocrotalus, and P. aff. P. rufescens. The darter is referrable to Anhinga melanogaster. The heron is identifiable as Ardea sp., and the gamefowl as Numidinae indet. (guineafowl). Pelecanus cf. P. onocrotalus is represented by, among other remains, a well-preserved partial skull. Four of the birds are thus referrable to extant taxa that provide some paleoenvironmental clues for Member I of the Kibish Formation. The two species of pelican, the darter, and the heron indicate the presence of local freshwater bodies, a lake or a slow river, supporting resources of fish. The guineafowl is poorly informative ecologically, but probably excludes the notion that the local terrestrial landscape was treeless. PMID:18656245

Louchart, Antoine; Haile-Selassie, Y; Vignaud, P; Likius, A; Brunet, M

2008-09-01

422

Rates of speciation in the fossil record  

NASA Technical Reports Server (NTRS)

Data from palaeontology and biodiversity suggest that the global biota should produce an average of three new species per year. However, the fossil record shows large variation around this mean. Rates of origination have declined through the Phanerozoic. This appears to have been largely a function of sorting among higher taxa (especially classes), which exhibit characteristic rates of speciation (and extinction) that differ among them by nearly an order of magnitude. Secular decline of origination rates is hardly constant, however; many positive deviations reflect accelerated speciation during rebounds from mass extinctions. There has also been general decline in rates of speciation within major taxa through their histories, although rates have tended to remain higher among members in tropical regions. Finally, pulses of speciation appear sometimes to be associated with climate change, although moderate oscillations of climate do not necessarily promote speciation despite forcing changes in species' geographical ranges.

Sepkoski, J. J. Jr; Sepkoski JJ, J. r. (Principal Investigator)

1998-01-01

423

FAST FOSSIL ROTATION OF NEUTRON STAR CORES  

SciTech Connect

It is argued that the superfluid core of a neutron star super-rotates relative to the crust, because stratification prevents the core from responding to the electromagnetic braking torque, until the relevant dissipative (viscous or Eddington-Sweet) timescale, which can exceed {approx}10{sup 3} yr and is much longer than the Ekman timescale, has elapsed. Hence, in some young pulsars, the rotation of the core today is a fossil record of its rotation at birth, provided that magnetic crust-core coupling is inhibited, e.g., by buoyancy, field-line topology, or the presence of uncondensed neutral components in the superfluid. Persistent core super-rotation alters our picture of neutron stars in several ways, allowing for magnetic field generation by ongoing dynamo action and enhanced gravitational wave emission from hydrodynamic instabilities.

Melatos, A., E-mail: amelatos@unimelb.edu.au [School of Physics, University of Melbourne, Parkville, VIC 3010 (Australia)

2012-12-10

424

Fossil Groups in the Local Universe  

NASA Technical Reports Server (NTRS)

The two galaxies observed as part of this project were originally selected as fossil group candidates because of their isolation from other galaxies and their apparent high X-ray luminosity and extended X-ray emission. However, the X-ray data available was minimal, being drawn from the ROSAT All-Sky Survey. We have performed an initial analysis of the XMM data from both galaxies and found that their gaseous halos are smaller, cooler, and less luminous than expected. In the case of NGC 57, the RASS estimate of extent and luminosity was biased because of a previously unidentified background group which is visible in the XMM data to one side of the galaxy. In the case of IC 153 1, the contribution from background point sources near the galaxy appears to be to blame. This suggests that both galaxies should be reclassified as isolated ellipticals. Such systems are very rare, and currently poorly understood; for comparison, there are now 6-10 known fossil groups, but only one isolated elliptical with useful X-ray data. We are currently re-analyzing the data for the two galaxies to take advantage of the calibration improvements of SAS 6.1, and to include calculations of the mass profiles of the two systems. A paper is currently in preparation dealing with the X-ray properties and environment of the galaxies, and we expect to submit this to the Astrophysical Journal within the next two months. Multi-band optical imaging of the field surrounding NGC 57 has been acquired to confirm its isolated status and provide more information on the background group. IC 1531 was accepted as a target in Chandra cycle 6 as part of a related proposal, and we intend to add this new observation to our XMM data when it becomes available. A second paper is planned to include the results of this combined analysis.

OSullivan, Ewan

2005-01-01

425

Profound 62 Myr Cycle in Fossil Diversity  

NASA Astrophysics Data System (ADS)

By combining the Sepkoski Compendium of Marine Fossil Genera with the new ICS 2004 geologic time scale, we have shown that the fossil record contains a 62 +/- 3 Myr cycle in the diversity of genera. This cycle has a very high statistical significance and while the associated changes in diversity are frequently gradual, all of the sharp drops known as major mass extinctions have occurred during declining phases of this cycle. This suggests that the timing or magnitude of these extinctions has been influenced by this periodic process; however, it remains unclear whether extinction events actually cause the cycle. While, we cannot explain the origin of the 62 Myr cycle, we believe it indicates a profound influence of some periodic physical process on Earth's environment throughout at least the last 540 Myr. In addition, the diversity data contain a statistically ambiguous 140 +/- 15 Myr cycle which could be due to changes of the same frequency reported in climate and cosmic rays. While all major mass extinctions seem to bear some relation to this cycle, we also find that the Permian-Triassic extinction was qualitatively unique. This extinction, the most severe in Earth's history, had substantial impact on classes of organisms that were historically resistant to the 62 Myr changes. This suggests that the processes leading to the P-T extinction may have included factors that were unique to that point in the Phanerozoic. It should be noted that the 62 Myr hypothesis is originally due to Thomson (Thomson KS, Nature 261, 578-580 (1976); Devs. in Palaeo. and Strat. 5, 377-404 (1977)) and Ager (Ager DV, Proc. Geologists' Assoc. 87, 131-159 (1977)), though their work has largely been forgotten. At the time of this submission, our revival of the 62 Myr hypothesis and related analysis is currently undergoing peer review at Nature.

Muller, R. A.; Rohde, R. A.

2004-12-01

426

Synthesis of chiral nonracemic homo-1-deoxyazasugars with D-talo-and L-allo-configuration via tandem Wittig [2+3] cycloaddition reaction  

Microsoft Academic Search

Wittig reaction of 6a,b proceeds with concomitant 1,3-dipolar cycloaddition of the azido function to the nonisolable triazoline 20 which isomerizes to diazoamine 7. Elimination of nitrogen from 7 provides vinylogous urethane 8 which can be transformed to heterocyclic ?-amino acid 10 and D-homo-1-deoxyazatalose (13). Catalytic hydrogenation of 7 and manipulation of functional groups give L-homo-1-deoxyazaallose (16) and ?-amino acid 18.

Claus Herdeis; Thomas Schiffer

1996-01-01

427

Fossil Leaves and Fossil Leaf n-Alkanes: Reconstructing the First Closed Canopied Rainforests  

NASA Astrophysics Data System (ADS)

Although the age and location is disputed, the rise of the first closed-canopy forest is likely linked with the expansion of angiosperms in the late Cretacous or early Cenozoic. The carbon isotope 'canopy effect' reflects the extent of canopy closure, and is well documented in ?13C values of the leaves and leaf lipids in modern forests. To test the extent of canopy closure among the oldest documented angiosperm tropical forests, we analyzed isotopic characteristics of leaf fossils and leaf waxes from the Guaduas and Cerrejón Formations. The Guaduas Fm. (Maastrichtian) contains some of the earliest angiosperm fossils in the Neotropics, and both leaf morphology and pollen records at this site suggest an open-canopy structure. The Cerrejón Fm. (Paleocene) contains what are believed to be the first recorded fossil leaves from a closed-canopy forest. We analyzed the bulk carbon isotope content (?13Cleaf) of 199 fossil leaves, as well as the n-alkane concentration and chain-length distribution, and ?13C of alkanes (?13Clipid) of 73 fossil leaves and adjacent sediment samples. Fossil leaves are dominated by eudicots and include ten modern plant families (Apocynaceae, Bombaceae, Euphorbaceae, Fabaceae, Lauraceae, Malvaceae, Meliaceae, Menispermaceae, Moraceae, Sapotaceae). We interpreted extent of canopy coverage based on the range of ?13Cleaf values. The narrow range of ?13C values in leaves from the Guaduas Fm (2.7‰) is consistent with an open canopy. A significantly wider range in values (6.3‰) suggests a closed-canopy signature for site 0315 of the Cerrejón Fm,. In contrast, at Site 0318, a lacustrine deposit, leaves had a narrow range (3.3‰) in ?13C values, and this is not consistent with a closed-canopy, but is consistent with leaf assemblages from a forest edge. Leaves that accumulate in lake sediments tend to be biased toward plants living at the lake edge, which do not experience closed-canopy conditions, and do not express the isotopic characteristics associated with canopy effect. A biomass flux-weighted model of alkane chain-length distribution and ?13Cleaf indicate n-alkanes extracted from bulk rock are consistent with inputs integrated over time from plants represented by fossil leaves. In a modern rainforest, we found leaf lipid amounts markedly higher in the shaded and moist understory, consistent with studies that show alkanes proffer fungal protection. Shade tolerance is associated with higher plant orders and, consistent with this, literature data for modern plants from 30 plant orders shows alkane production in asterids and rosids is 2 to 3 times greater than in basal angiosperms or gymnosperms. The lower clades tend to contain greater amounts of terpenoids and novel benzylisoquinoline alkaloids, rather than alkanes. For our three fossil floras, alkane abundance is strongly influenced by depositional setting, with preservation best in the lacustrine setting. Within each site, abundance patterns are potentially influenced by both taxonomic affiliation and by canopy structure as measured by ?13Cleaf values, and such relationships shed light on the combined influences of plant evolution, canopy structure and the function of biochemical resources on the geochemical record of the first rainforests.

Graham, H. V.; Freeman, K. H.

2013-12-01

428

Fossil fuel decarbonization technology for mitigating global warming  

Microsoft Academic Search

It has been understood that production of hydrogen from fossil and carbonaceous fuels with reduced COâ emission to the atmosphere is key to the production of hydrogen-rich fuels for mitigating the COâ greenhouse gas climate change problem. The conventional methods of hydrogen production from fossil fuels (coal, oil, gas and biomass) include steam reforming and water gas shift mainly of

Steinberg

1998-01-01

429

Combined solar and fossil fuel systems for electric power generation  

Microsoft Academic Search

The paper is intended to present a parametric study for the combined solar and fossil fuel system for electric power generation. The combined system is so designed that the solar energy will be utilized to a maximum extent at the time when the solar energy is available. The balance of energy requirement is met by burning fossil fuels such as

K. W. Li; J. Cashman

1981-01-01

430

Atmospheric heating and cooling from fossil-fuel combustion  

Microsoft Academic Search

Burning fossil fuels produces not only carbon dioxide but also sulfur dioxide. Atmospheric oxidation converts sulfur dioxide into sulfate aerosols which scatter solar radiation and lead to increased reflectivity of clouds. Both effects are thought to cool the atmosphere and offset to some extent warming from increased carbon dioxide. If estimates are accurate, the net radiative forcing resulting from fossil-fuel

1994-01-01

431

Alternative energy: Can renewable energy sources replace fossil fuels  

Microsoft Academic Search

Fossil fuels have been the prime mover of industrial life for some 200 years. The burning of coal and oil have saved inestimable amounts of time and labor while substantially raising living standards around the world. But many scientists now say the use of fossil fuels, which account for 85% of US energy use, contributes to global warming and could

1992-01-01

432

Fossil Plants as Indicators of the Phanerozoic Global Carbon Cycle  

Microsoft Academic Search

Developments in plant physiology since the 1980s have led to the realization that fossil plants archive both the isotopic composition of atmospheric CO2 and its concentration, both critical integrators of carbon cycle processes through geologic time. These two carbon cycle signals can be read by analyzing the stable carbon isotope composition ([delta ]13) of fossilized terrestrial organic matter and by

D. J. Beerling; D. L. Royer

2002-01-01

433

Nonrandom decay of chordate characters causes bias in fossil interpretation  

Microsoft Academic Search

Exceptional preservation of soft-bodied Cambrian chordates provides our only direct information on the origin of vertebrates. Fossil chordates from this interval offer crucial insights into how the distinctive body plan of vertebrates evolved, but reading this pre-biomineralization fossil record is fraught with difficulties, leading to controversial and contradictory interpretations. The cause of these difficulties is taphonomic: we lack data on

Robert S. Sansom; Sarah E. Gabbott; Mark A. Purnell

2010-01-01

434

Where is the Fossil Evidence for Gondwanan Crayfish?  

Microsoft Academic Search

Crayfish body- and ichnofossils recently reported from Lower Permian and Lower Triassic strata of Antarctica have been reinterpreted to be the body fossils of euthycarcinoid arthropods and the burrows of small- to large-sized therapsids (mammal-like reptiles). The earliest fossil evidence of crayfish presence and activity in continental deposits is still from the Laurasian continents of Pangea. This evidence is in

Stephen T. Hasiotis

2002-01-01

435

Surveying a fossil oyster reef using terrestrial laser scanning  

Microsoft Academic Search

The Korneuburg Basin, situated north-west of Vienna, is well known to contain a rich variety of fossils from the Early Miocene (16.5 ma) and therefore has been investigated extensively by scientists in the past decades. An exceptional discovery was made in 2005: a large fossil oyster reef has been excavated and documented carefully during the last years. Aside from the

A. Haring; U. Exner; M. Harzhauser

2009-01-01

436

Field Project: Fossil Collection, Identification, and Report Writing  

NSDL National Science Digital Library

The primary purposes of this exercise are to assemble a collection of fossils in the field, to gain experience in fossil identification, to interpret the mode of life and environment in which the organisms lived, and to present this in a written format . This exercise is designed to sharpen the observational skills that are steadily developed during lab and integrate them with lecture concepts.

Leslie, Steve

437

Reconstructing Ancient Environments: A Role for Fossils in Biology Courses.  

ERIC Educational Resources Information Center

Discusses how the nature of the rock and, particularly, its fossils can be used in ecology courses for schools and colleges to help students to deduce the nature of the environment at the time the rock was deposited. A checklist and ways of identifying geological sites and fossils are included. (HM)

Angseesing, J. P. A.

1979-01-01

438

World catalog of extant and fossil Corethrellidae (Diptera).  

PubMed

A world catalog of extant and fossil frog-biting midges (Diptera: Corethrellidae) provides full type information, known life stages, and distribution of each species. There are 105 extant and seven fossil species of Corethrellidae but unnamed species are known from Costa Rica, Colombia and Madagascar. New information on types and other important specimens are provided. PMID:24870687

Borkent, Art

2014-01-01

439

Fossilization and Learning Strategies in Second Language Acquisition.  

ERIC Educational Resources Information Center

In interlanguage, the transitional state reaching from one's native language to a given target language, phonological, morphological, syntactic, lexical, sociocultural, or psycholinguistic errors may be generated and systematized by the process of fossilization. Depending on the amount of time needed for remediation, fossilized features may be…

Sims, William R.

1989-01-01

440

Reducing CO 2 emissions by substituting biomass for fossil fuels  

Microsoft Academic Search

Replacing fossil fuels with sustainably-produced biomass will reduce the net flow of CO2 to the atmosphere. We express the efficiency of this substitution in reduced emissions per unit of used land or biomass and in costs of the substitution per tonne of C. The substitution costs are calculated as the cost difference between continued use of fossil fuels at current

Leif Gustavsson; Pål Börjesson; Bengt Johansson; Per Svenningsson

1995-01-01

441

Fossil Fuel Combustion and the Major Sedimentary Cycle  

Microsoft Academic Search

The combustion of the fossil fuels coal, oil, and lignite potentially can mobilize many elements into the atmosphere at rates, in general, less than but comparable to their rates of flow through natural waters during the weathering cycle. Since the principal sites of fossil fuel combustion are in the mid-latitudes of the Northern Hemisphere, changes in the composition of natural

K. K. Bertine; Edward D. Goldberg

1971-01-01

442

The Great Fossil Fiasco: Teaching about Peer Review.  

ERIC Educational Resources Information Center

Describes a lesson that engages middle school students in learning about peer review. Uses the article "Archaeoraptor Fossil Trail," which was published in the November, 1999 issue of "National Geographic" as an example of a real life story of how peer review forces scientists to critically re-examine a fossil discovery. (SOE)

Gift, Nancy; Krasny, Marianne

2003-01-01

443

Early cyanobacterial fossil record: preservation, palaeoenvironments and identification  

Microsoft Academic Search

The cyanobacterial fossil record is among the oldest for any group of organisms, possibly reaching back to 3500 Ma ago. The molecular phylogeny of cyanobacteria is complementary to the fossil findings, confirming the antiquity of the group, the role of cyanobacteria in the evolution of planetary primary production, and the symbiotic origins of plastids in algae and plants from cyanobacterial

Stjepko Golubic; Lee Seong-Joo

1999-01-01

444

Fossil fuel production from the southeastern United States  

Microsoft Academic Search

The southeastern states (VA, NC, SC, KY, TN, GA, FL, AL, and MS) are blessed with geologic diversity and a wealth of fossil fuels. Currently, only a fraction of these resources are being produced and utilized. The multitude of fossil fuel resources in the southeastern states includes significant oil and gas accumulations and prolific coal deposits. Oil and gas are

E. A. Mancini; B. L. Bearden

1993-01-01

445

Availability of Fossil-Fired Steam Power Plants.  

National Technical Information Service (NTIS)

Fossil-fired power plants of 600 MW or larger constitute a major proportion of the baseload capacity in the country but have the poorest availability record of any size category. Two primary aims of the EPRI Fossil Plant Performance and Reliability Progra...

D. Anson

1977-01-01

446

Flavonoids and other chemical constituents of fossil miocene zelkova (ulmaceae).  

PubMed

Organic solvent extractions of Zelkova oregoniana, a Miocene angiosperm compression fossil, indicate the chemical preservation of kaempferol, dihydrokaempferol, an n-alkane chain length range of 10 to 32 carbons, hydroxy acids, steranes, triterpenoids, and methyl pheophorbide a. This appears to be the oldest occurrence of flavonoids in fossil sediments reported. PMID:17821805

Niklas, K J; Giannasi, D E

1977-05-20

447

Special Creation and the Fossil Record: The Central Fallacy.  

ERIC Educational Resources Information Center

Fossil records are used to point out two major flaws in the scientific creationist theory: (1) factual evidence does not support the theory, and (2) the creationists' own characterization of the fossil record contradicts their theory. Claims that creationists avoid discussing specifics about their model because of weaknesses. (DC)

Miller, Kenneth R.

1982-01-01

448

Microalgal and terrestrial transport biofuels to displace fossil fuels  

Microsoft Academic Search

Terrestrial transport biofuels differ in their ability to replace fossil fuels. When both the conversion of solar energy into biomass and the life cycle inputs of fossil fuels are considered, ethanol from sugarcane and biodiesel from palm oil do relatively well, if compared with ethanol from corn, sugar beet or wheat and biodiesel from rapeseed. When terrestrial biofuels are to

Lucas Reijnders

2009-01-01

449

Fossils of the Gault Clay and Folkestone Beds of Kent, UK  

NSDL National Science Digital Library

A diverse collection of lower Cretaceous (Albian) fossils is featured on this site. Fossil photos, illustrations and information about each suborder are provided for an array of fossil groups. Specific fossil groups include Ammonoidea, Bivalvia, Cephalopoda, Cnidaria (Corals), Echinodermata, Fish, Foraminifera, Gastropoda, Ostracoda, and Scaphopoda. Short discussions of United Kingdom geology, Albian stratigraphy, geologic time and fossil imaging techniques are also included.

Fred, Clouter

450

Synthesizing and databasing fossil calibrations: divergence dating and beyond  

PubMed Central

Divergence dating studies, which combine temporal data from the fossil record with branch length data from molecular phylogenetic trees, represent a rapidly expanding approach to understanding the history of life. National Evolutionary Synthesis Center hosted the first Fossil Calibrations Working Group (3–6 March, 2011, Durham, NC, USA), bringing together palaeontologists, molecular evolutionists and bioinformatics experts to present perspectives from disciplines that generate, model and use fossil calibration data. Presentations and discussions focused on channels for interdisciplinary collaboration, best practices for justifying, reporting and using fossil calibrations and roadblocks to synthesis of palaeontological and molecular data. Bioinformatics solutions were proposed, with the primary objective being a new database for vetted fossil calibrations with linkages to existing resources, targeted for a 2012 launch.

Ksepka, Daniel T.; Benton, Michael J.; Carrano, Matthew T.; Gandolfo, Maria A.; Head, Jason J.; Hermsen, Elizabeth J.; Joyce, Walter G.; Lamm, Kristin S.; Patane, Jose S. L.; Phillips, Matthew J.; Polly, P. David; Van Tuinen, Marcel; Ware, Jessica L.; Warnock, Rachel C. M.; Parham, James F.

2011-01-01

451

Fossil-energy program. Progress report for June 1981  

SciTech Connect

This report - the eighty-third of series - is a compendium of monthly progress reports for the ORNL research and development programs that are in support of the increased utilization of coal and other fossil fuel alternatives as sources of clean energy. The projects reported this month include those for coal conversion development, chemical research and development, materials technology, component development and process evaluation, technical support to major liquefaction projects, process analysis and engineering evaluations, fossil energy environmental analysis, flue gas desulfurization, coal preparation waste utilization, atmospheric fluidized bed coal combustor for cogeneration, TVA FBC demonstration plant program technical support, PFBC systems analysis, fossil fuel applications assessments, performance assurance system support for fossil energy projects, international energy technology assessment, generalized equilibrium models for liquid and gaseous fuel supplies, analyses of coal production goals, and fossil energy information center.

Not Available

1981-08-01

452

The rhizome of Reclinomonas americana, Homo sapiens, Pediculus humanus and Saccharomyces cerevisiae mitochondria  

PubMed Central

Background Mitochondria are thought to have evolved from eubacteria-like endosymbionts; however, the origin of the mitochondrion remains a subject of debate. In this study, we investigated the phenomenon of chimerism in mitochondria to shed light on the origin of these organelles by determining which species played a role in their formation. We used the mitochondria of four distinct organisms, Reclinomonas americana, Homo sapiens, Saccharomyces cerevisiae and multichromosome Pediculus humanus, and attempted to identify the origin of each mitochondrial gene. Results Our results suggest that the origin of mitochondrial genes is not limited to the Rickettsiales and that the creation of these genes did not occur in a single event, but through multiple successive events. Some of these events are very old and were followed by events that are more recent and occurred through the addition of elements originating from current species. The points in time that the elements were added and the parental species of each gene in the mitochondrial genome are different to the individual species. These data constitute strong evidence that mitochondria do not have a single common ancestor but likely have numerous ancestors, including proto-Rickettsiales, proto-Rhizobiales and proto-Alphaproteobacteria, as well as current alphaproteobacterial species. The analysis of the multichromosome P. humanus mitochondrion supports this mechanism. Conclusions The most plausible scenario of the origin of the mitochondrion is that ancestors of Rickettsiales and Rhizobiales merged in a proto-eukaryotic cell approximately one billion years ago. The fusion of the Rickettsiales and Rhizobiales cells was followed by gene loss, genomic rearrangements and the addition of alphaproteobacterial elements through ancient and more recent recombination events. Each gene of each of the four studied mitochondria has a different origin, while in some cases, multichromosomes may allow for enhanced gene exchange. Therefore, the tree of life is not sufficient to explain the chimeric structure of current genomes, and the theory of a single common ancestor and a top-down tree does not reflect our current state of knowledge. Mitochondrial evolution constitutes a rhizome, and it should be represented as such. Reviewers This article was revised by William Martin, Arcady Mushegian and Eugene V. Koonin.

2011-01-01

453

Structure and spectroscopic studies of homo-and heterometallic complexes of adipic acid dihydrazide.  

PubMed

A single crystal of adipic acid dihydrazide, ADH, has been analyzed. Its reaction with Co(2+), Ni(2+), Cu(2+), Zn(2+), Cd(2+), Hg(2+), Ag(+), Pd(2+) and/or Pt(2+) gave homometallic and heterometallic complexes which are characterized by partial elemental analysis, spectra (MS, ESR, (1)H NMR, electronic; IR), thermal analysis and magnetic measurements. Some complexes: Zn(0.73)Cu(ADH)Cl4·H2O; Zn(0.71)Hg(0.36)(ADH)Cl4·H2O; Zn(0.65)Cd(0.46)(ADH)Cl4·½H2O; Zn(0.75)Co(0.41)(ADH-2H)Cl2·3H2O; Cd0.85Co0.43(ADH)Cl4·½EtOH were isolated having nonstiochiometric metal ratios. The ligand behaves as a neutral (bidentate or tetradentate) and/or binegative tetradentate. A square-pyramid, square-planar and tetrahedral structures were proposed for the homo Co(II), Cu(II) and Ni(II) complexes, respectively. A similar and different stereochemistry around each metal ion (tetrahedral+tetrahedral; tetrahedral+square-planar; tetrahedral+tetrahedral and/or tetrahedral+octahedral) was suggested for the heterometallic complexes. Some complexes were found highly stable with stability point >240 °C; the most stable is [HgNi(ADH-2H)Cl2]. The presence of diamagnetic atom (Zn, Cd or Hg) reduces the magnetic moments and gave anomalous moments. The degradation steps and the hydrated complexes are confirmed through the TGA study. The order of covalency of [Zn(0.73)Cu(ADH)Cl4]·H2O, [CdCu(ADH)Cl4]·H2O and [HgCu(ADH-2H)Cl2] matches with the size of the second metal (Zn complex>Cd complex>Hg complex). Some heterometallic complexes were found nonstoichiometric through the analysis of their metal content and supported by TGA. PMID:24530707

Jeragh, Bakir; El-Asmy, Ahmed A

2014-05-01

454

Ag(I)-mediated homo and hetero pairs of guanosine and cytidine: Monitoring by circular dichroism spectroscopy  

NASA Astrophysics Data System (ADS)

Ag(I)-containing compounds are attractive as antibacterial and antifungal agents. The renewed interest in the application of silver(I) compounds has led to the need for detailed knowledge of the mechanism of their action. One of the possible ways is the coordination of Ag(I) to G-C pairs of DNA, where Ag+ ions form Ag(I)-mediated base pairs and inhibit the transcription. Herein, a systematic chiroptical study on silver(I)-mediated homo and mixed pairs of the C-G complementary-base derivatives cytidine(C) and 5'-guanosine monophosphate(G) in water is presented. Ag(I)-mediated homo and hetero pairs of G and C and their self-assembled species were studied under two pH levels (7.0 and 10.0) by vibrational (VCD) and electronic circular dichroism(ECD). VCD was used for the first time in this field and showed itself to be a powerful method for obtaining specific structural information in solution. Based on results of the VCD experiments, the different geometries of the homo pairs were proposed under pH 7.0 and 10.0. ECD was used as a diagnostic tool to characterize the studied systems and as a contact point between the previously defined structures of the metal or proton mediated pairs of nucleobases and the systems studied here. On the basis of the obtained data, the formation of the self-assembled species of cytidine with a structure similar to the i-motif structure in DNA was proposed at pH 10.0.

Goncharova, Iryna

2014-01-01

455

Genetic evidence of an early exit of Homo sapiens sapiens from Africa through eastern Africa.  

PubMed

The out-of-Africa scenario has hitherto provided little evidence for the precise route by which modern humans left Africa. Two major routes of dispersal have been hypothesized: one through North Africa into the Levant, documented by fossil remains, and one through Ethiopia along South Asia, for which little, if any, evidence exists. Mitochondrial DNA (mtDNA) can be used to trace maternal ancestry. The geographic distribution and variation of mtDNAs can be highly informative in defining potential range expansions and migration routes in the distant past. The mitochondrial haplogroup M, first regarded as an ancient marker of East-Asian origin, has been found at high frequency in India and Ethiopia, raising the question of its origin. (A haplogroup is a group of haplotypes that share some sequence variations.) Its variation and geographical distribution suggest that Asian haplogroup M separated from eastern-African haplogroup M more than 50,000 years ago. Two other variants (489C and 10873C) also support a single origin of haplogroup M in Africa. These findings, together with the virtual absence of haplogroup M in the Levant and its high frequency in the South-Arabian peninsula, render M the first genetic indicator for the hypothesized exit route from Africa through eastern Africa/western India. This was possibly the only successful early dispersal event of modern humans out of Africa. PMID:10581031

Quintana-Murci, L; Semino, O; Bandelt, H J; Passarino, G; McElreavey, K; Santachiara-Benerecetti, A S

1999-12-01

456

Can the exchange-correlation potential of density functional theory be expressed solely in terms of HOMO and LUMO properties?  

NASA Astrophysics Data System (ADS)

In a recent Letter with Ayers, we have demonstrated that the idempotent Dirac density matrix generated by any local potential V( r) can be derived in terms of