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PALAEOENVIRONMENTAL RECONSTRUCTION OF DMANISI SITE

April 01, 2010

Messager et. al. published 2 papers, one in Quaternary International: Palaeoenvironmental reconstruction of Dmanisi site (Georgia) based on palaeobotanical data; and other in Palaeogeography, Paleoclimatology, Palaeoecology: Palaeoecological inplications of the Lower Pleistocene phytolith record from the Dmanisi Site (Georgia), saying that early Pleistocene Dmanisi environment was well-represented with grasses, additionally, there have been periods of increased aridity which was contemporaneous of the human occupations of the site.

Abstract (QI)

The first hominid expansions out of Africa date to the Lower Pleistocene. As environmental changes are widely thought to be correlated to important steps in hominids' history [DeMenocal, P.B., Bloemendal, J., 1995. Plio-Pleistocene subtropical African climate variability and the paleoenvironment of hominid evolution: a combined data-model approach. In: Vrba, E., Denton, G., Burckle, L., Partridge, T. (Eds.), Paleoclimate and Evolution with Emphasis on Human Origins. Yale University Press, New Haven, pp. 262–288; Potts, R., 1998. Environmental hypotheses of hominin evolution. Yearbook of Physical Anthropology 41, 93–136], what kind of environments would they have encountered on their arrival in Eurasian areas? The site of Dmanisi (Lesser Caucasus, Georgia) is well-dated to the very beginning of Matuyama chron (ca. 1.77 Ma), and thus corresponds to one of the oldest dispersal events from Africa into Eurasia. New archaeological investigations of the lower Pleistocene sequences at Dmanisi yielded both human and faunal remains within a secure geochronological context. Although palaeoecological data, based primarily on faunal taxa are well-known, questions remain regarding the palaeoenvironmental and palaeoclimatic contexts of this site.

These questions are addressed using multiproxy palaeobotanical analyses (i.e. phytoliths, pollen grains and carpo-remains) on the Dmanisi material. Focuses on several profiles help to reconstruct the distribution and evolution of vegetation at the site over time. The results show a composite temperate ecosystem with grass species being well-represented. In the mid-part of the sequence, evidence of enhanced aridity contemporaneous with hominid occupation is recorded. Although these reconstructed environments are similar to African savannah because of the abundance of grasses, arid conditions and the abundance of large mammal species, they differ with respect to the vegetation taxa, which are mostly composed of temperate plants.ca. 1.77 Ma), and thus corresponds to one of the oldest dispersal events from Africa into Eurasia. New archaeological investigations of the lower Pleistocene sequences at Dmanisi yielded both human and faunal remains within a secure geochronological context. Although palaeoecological data, based primarily on faunal taxa are well-known, questions remain regarding the palaeoenvironmental and palaeoclimatic contexts of this site.

 

Abstract (PPP)

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.