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Hemmer H.,Johannes Gutenberg University Mainz | Kahlke R.-D.,Senckenberg Institute | Vekua A.K.,Georgian National Museum
Neues Jahrbuch fur Geologie und Palaontologie - Abhandlungen | Year: 2010

Comparative evaluation of fossil remains of the lower dentition of the jaguar, Panthera onca (LINNAEUS, 1758) in the light of recent DNA assessment allows a comprehensive phylogeographic interpretation. The speciation process led a jaguar stem population, clearly of African origin, to disperse over Europe during the time of the Olduvai polarity subchron (1.95-1.77 Myr) (Panthera onca toscana). Based on a hemimandible from Dmanisi, Republic of Georgia, dated to about 1.77 Myr, a new taxon Panthera onca georgica ssp. nov. is proposed for the earliest known Asian member of the species. Its generalized, more cutting dentition mediates between the contemporaneous P. onca toscana and the two later sister subspecies, the Eurasian P. onca gombaszoegensis, which is characterized by a specialized cutting and crushing dentition, and the North American P onca augusta. Placing the tooth differences within geographic coordinates indicates a central Asian evolutionary node between the latter two forms. Transcontinental dispersal probably brought the jaguar to North America during a glacial period between the Jaramillo polarity subchron and the end of the Matuyama magnetochron (0.99-0.78 Myr), to finally reach South America not before the Rancholabrean. Divergent taxonomie concepts for Pleistocene jaguars are discussed: single species P. onca with several subspecies, two species P gombaszoegensis and P. onca, or three species P. toscana, P gombaszoegensis and P. onca. © 2010 Schwelzerbart'sche Verlagsbuchhandlung, Stuttgart, Germany.

Garcia T.,French Natural History Museum | Feraud G.,University of Nice Sophia Antipolis | Falgueres C.,French Natural History Museum | de Lumley H.,Institute Of Paleontologie Humaine | And 2 more authors.
Quaternary Geochronology | Year: 2010

Several hominid remains have been discovered in the open-air site of Dmanisi (Georgia), the oldest prehistoric site in Eurasia. Two major arguments prove that this site is close in age to the Plio-Pleistocene boundary: a Villafranchian fauna and the morphological characteristics of hominid remains recently ascribed to Homo georgicus. Direct dating of the lower hominid-bearing level was carried out on volcanic glass and minerals using the 40Ar/39Ar method. The concordant results from two different sampled locations allow the determination of the age of the earliest human presence in Eurasia. This radioisotopic result strengthens the argument that the first dispersal of hominids outside Africa occurred at least 1.8Ma ago. © 2009 Elsevier B.V.

Messager E.,French Natural History Museum | Lordkipanidze D.,Georgian National Museum | Delhon C.,French National Center for Scientific Research | Ferring C.R.,University of North Texas
Palaeogeography, Palaeoclimatology, Palaeoecology | Year: 2010

Archaeological investigations of the lower Pleistocene deposits at Dmanisi (Lesser Caucasus, Georgia) have yielded an assemblage of hominin and faunal remains within a well-dated context. Although abundant vertebrate fossils have been recovered, paleobotanical studies have been limited. To address this, phytolith analysis has been conducted on two sections in order to reconstruct the distribution and evolution of vegetation throughout the entire sedimentary sequence. Large concentrations of phytoliths were recovered and analysed, permitting the reconstruction of climatic indices. The environmental data obtained from these phytolith assemblages are consistent with other palaeoecological data (i.e. geological, faunal and other archaeobotanical records). When considered together, they indicate an environment in which grasses were well-represented. In addition, the climatically important water stress indices derived from Dmanisi's phytolith assemblages suggest a period of increased aridity in the middle part of the stratigraphic sequence, which is contemporaneous with human occupations of the site. © 2010 Elsevier B.V. All rights reserved.

Margvelashvili A.,University of Zurich | Zollikofer C.P.E.,University of Zurich | Lordkipanidze D.,Georgian National Museum | Peltomaki T.,University of Tampere | De Leon M.S.P.,University of Zurich
Proceedings of the National Academy of Sciences of the United States of America | Year: 2013

The Plio-Pleistocene hominin sample from Dmanisi (Georgia), dated to 1.77 million years ago, is unique in offering detailed insights into patterns of morphological variation within a paleodeme of early Homo. Cranial and dentoalveolar morphologies exhibit a high degree of diversity, but the causes of variation are still relatively unexplored. Here we show that wear-related dentoalveolar remodeling is one of the principal mechanisms causing mandibular shape variation in fossil Homo and in modern human hunter- gatherer populations. We identify a consistent pattern of mandibular morphological alteration, suggesting that dental wear and compensatory remodeling mechanisms remained fairly constant throughout the evolution of the genus Homo. With increasing occlusal and interproximal tooth wear, the teeth continue to erupt, the posterior dentition tends to drift in a mesial direction, and the front teeth become more upright. The resulting changes in dentognathic size and shape are substantial and need to be taken into account in comparative taxonomic analyses of isolated hominin mandibles. Our data further show that excessive tooth wear eventually leads to a breakdown of the normal remodeling mechanisms, resulting in dentognathic pathologies, tooth loss, and loss of masticatory function. Complete breakdown of dentognathic homeostasis, however, is unlikely to have limited the life span of early Homo because this effect was likely mediated by the preparation of soft foods.

Agusti J.,Rovira i Virgili University | Lordkipanidze D.,Georgian National Museum
Quaternary Science Reviews | Year: 2011

In this paper we review a number of scenarios which have been proposed to explain the first hominin " out of Africa" at the base of the Pleistocene. These are the brain expansion scenario, the cultural exclusion scenario, the migratory wave scenario and the common African home scenario. These scenarios are checked against the current evidence provided by the Georgian site of Dmanisi, which contains the oldest Eurasian hominins. Therefore, it is concluded that none of these scenarios fits with the existing evidence, and that the only real African influence in Dmanisi is restricted to early Homo itself. In order to explain the presence of early Homo at Dmanisi, it is concluded that the expansion out of Africa should have happened before the actual datum of Dmanisi, most probably linked to the spread of Mode 1 tools in Africa. © 2010 Elsevier Ltd.

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