Life and death at Dmanisi, Georgia: Taphonomic signals from the fossil mammals.

There are many hypotheses regarding influences on the early hominin biogeographic spread into Eurasia; among them is increased meat-eating. Dmanisi in Georgia is one of the rare Early Pleistocene sites in Eurasia, and here we present primary information and analysis of the medium and large mammal taphonomy, contributing information about site formation and the hominins' interaction with the fauna. Nearly 85% of the specimens come from the B1 stratum. Relative abundances of mammal families demonstrate some bias toward carnivores, especially Canis borjgali, and diverse Felidae species. Bones display little weathering. Post-depositional surface modifications and matrix obscure many bone surfaces, but carnivore tooth marking is the most common bone surface modification from the nutritive taphonomic phase. Tooth pits are large, in the size range of those made by modern Crocuta crocuta and Panthera leo. Breakage variables indicate most breaks occurred while the bones were still fresh, many by carnivore consumption. Fairly even limb bone representation of herbivores suggests carcasses were introduced to the site nearly whole. Hominin tool marks are present in low frequencies, but they suggest a variety of behaviors. These marks are found on Equus, Palaeotragus, Bison, large cervids, Pseudodama, Canis, and Mammuthus. Some were made by filleting proximal limb segments, and so are likely indicative of early access to carcasses, while other marks suggest scavenging. The Homo taphonomic variables resemble the rest of the taphonomic signatures from the site with little weathering, a slightly higher percentage of their bones are whole, but only a few have probable carnivore damage. The assemblage characteristics are compared to modern actualistic and experimental assemblages, and it is concluded that Dmanisi presents a palimpsest of hyena denning, felid activity, hominin meat-eating and likely natural deaths.

Zoogeographic significance of Dmanisi large mammal assemblage.

We undertake a comparative mammalian zoogeographic analysis with the aim of revealing the extent to which the Dmanisi Early Pleistocene large mammal assemblage resembles, at the genus level, African, Arabian, and Eurasian localities of similar age. The inclusion of Old World Pliocene and Pleistocene mammalian faunas provides us with insights into the provincial origins of specific mammalian taxa and permits us to assess the relative affiliation of the Dmanisi mammalian faunas to other faunas in the Old World. Our analysis also allows us to consider hypotheses about the timing and direction of zoogeographic connections between western Eurasia and Africa during the Early Pleistocene. We utilize multiple zoogeographic analytical tools as a cross-comparison of Dmanisi with 42 other Eurasian and African mammalian-bearing localities between 2.7 and 0.7 Ma. Overall, we find that Dmanisi compares most closely with a subgroup of Greek, Italian, and Spanish localities that are slightly younger than Dmanisi itself. This could suggest a progressive dispersal from East to West of the large mammal communities during the late Early Pleistocene and the first occurrence at Dmanisi, and then later in Western Europe, of some taxa such as Stephanorhinus ex gr. etruscus-hundsheimensis, Equus altidens, Bison georgicus, Soergelia minor, Megantereon whitei, Canis borjgali, Canis (Xenocyon) lycaonoides. Dmanisi's habitats included drier areas, probably of open wooded savannah and grassland and by mountainous to semiarid rocky terrain. There is evidence that Dmanisi records short intervals of increased aridity in the middle part of the succession contemporaneous with the occurrence of Homo.

The Dmanisi Equus: Systematics, biogeography, and paleoecology.

The Equus datum has been established as a geochronologic 'instantaneous' migratory event of a North American Equus species into Eurasia at the beginning of the Pleistocene (2.58 Ma). A remarkable radiation of Equus followed across Eurasia and Africa. Dmanisi includes excellent remains of Equus, well calibrated between 1.85 and 1.76 Ma. Our morphologic and morphometric analyses of the augmented Dmanisi Equus sample support the co-occurrence of Equus stenonis and Equus altidens in the sequence. Dmanisi E. stenonis is found to be morphologically similar to the European E. stenonis populations and represents the best well-dated easternmost occurrence of this species in Eurasia. The Dmanisi E. altidens represents the oldest well-calibrated occurrence of this species in Western Eurasia. Our analyses demonstrate that E. altidens extended its range westward from west Asia to Greece, Germany, Italy, Spain, and possibly France. Our results do not support distinguishing multiple subspecies of E. altidens, including E. altidens altidens, E. altidens granatensis and E. stenonis mygdoniensis. The Dmanisi cranial and postcranial samples exhibit morphologies close both to extant hemiones and zebras. Equus altidens is believed to have been well adapted to newly emergent arid environments in western Eurasia during the late Early and early Middle Pleistocene. The first occurrence of E. altidens at Dmanisi marks an important turnover in the horse communities of the late Early Pleistocene, with a dispersion of this species from West Asia to West Europe ca. 1.8 Ma.

Paleoecology, biochronology, and paleobiogeography of Eurasian Rhinocerotidae during the Early Pleistocene: The contribution of the fossil material from Dmanisi (Georgia, Southern Caucasus).

Rhinocerotidae represents a common element in the Eurasian Pleistocene faunas. Origin, dispersal route, and biochronology of several species are still poorly understood due to gaps in the fossil record, in particular from central Eurasia. A remarkable collection of rhinoceros remains was recovered from the Early Pleistocene site of Dmanisi (Georgia). This collection is unique for the Early Pleistocene Rhinocerotidae records due to its abundance in remains, its age (ca 1.8 Ma) and geographic position (between Eastern and Western Eurasia). Two crania, which display some different morphological traits, are assigned to two different morphotypes and investigated by means of geometric morphometrics using landmarks and semilandmarks. Shapes in lateral and dorsal views of different Rhinocerotini species are compared with the studied crania to infer paleoecological information. The shape in the lateral view reflects ecological niche, in particular feeding type from browsing to grazing, and it also represent taxonomic discrimination. Morphotypes 1 and 2 from Dmanisi fall in two different clusters, corresponding to two different species, notably in lateral view. The results suggest a niche partitioning during the Early Pleistocene of Dmanisi between a browse-dominated and a grass-dominated mixed feeders, or possibly the presence of two ecomorphotypes of the same species. A comprehensive update of the Early Pleistocene occurrences of Eurasian Rhinocerotidae is reported in the discussion on the paleoecology of the extinct Northern Eurasian rhinocerotines.

Spatial patterning of the archaeological and paleontological assemblage at Dmanisi, Georgia: An analysis of site formation and carnivore-hominin interaction in Block 2.

This study addresses the roles of biotic agents in site formation in the B1 strata of Block 2 at Dmanisi, Georgia, using theoretical and analogous frameworks for the interpretation of spatial behaviors of carnivores and hominins. For this study, stone material, faunal remains, and coprolites are analyzed to determine if any spatially distinct behaviors can be identified, located, and attributed to either hominins or carnivores. Faunal, stone, and coprolite assemblages are compared with each other, and lithic, taxonomic, and taphonomic subassemblages are compared with the overall distribution of their parent material. The spatial and taphonomic signatures suggest that hominin activity was only a small part of the contributing factors to site formation, whereas carnivores played a major role in the accumulation of bone.

The fossil record of the genus Varanus from the Southern Caucasus (Armenia, Georgia).

The Southern Caucasus, with its special geographic position and complex topography, is a well-known biodiversity hotspot. However, the formation of this hotspot remains largely unstudied. To reveal this, a thorough study of the fossil record of the region is necessary. In the present paper, we describe for the first time fossil monitor lizards (Varanus sp.) from two late Miocene localities from the Southern Caucasus (Jradzor, Armenia and Tetri Udabno, Georgia). We suggest that both fossils belong to a small-sized monitor lizard, comparable to the present-day species found in Iran and the Middle East (e.g., Iraq, Saudi Arabian)-the most western part of the extant monitor lizards' Eurasian distribution range. Our finds show that the genus had a broad distribution in the Eastern Paratethyan region during the late Miocene. In addition, we provide the probable temperature ranges for fossil localities.

Early Pleistocene enamel proteome from Dmanisi resolves Stephanorhinus phylogeny.

The sequencing of ancient DNA has enabled the reconstruction of speciation, migration and admixture events for extinct taxa1. However, the irreversible post-mortem degradation2 of ancient DNA has so far limited its recovery-outside permafrost areas-to specimens that are not older than approximately 0.5 million years (Myr)3. By contrast, tandem mass spectrometry has enabled the sequencing of approximately 1.5-Myr-old collagen type I4, and suggested the presence of protein residues in fossils of the Cretaceous period5-although with limited phylogenetic use6. In the absence of molecular evidence, the speciation of several extinct species of the Early and Middle Pleistocene epoch remains contentious. Here we address the phylogenetic relationships of the Eurasian Rhinocerotidae of the Pleistocene epoch7-9, using the proteome of dental enamel from a Stephanorhinus tooth that is approximately 1.77-Myr old, recovered from the archaeological site of Dmanisi (South Caucasus, Georgia)10. Molecular phylogenetic analyses place this Stephanorhinus as a sister group to the clade formed by the woolly rhinoceros (Coelodonta antiquitatis) and Merck's rhinoceros (Stephanorhinus kirchbergensis). We show that Coelodonta evolved from an early Stephanorhinus lineage, and that this latter genus includes at least two distinct evolutionary lines. The genus Stephanorhinus is therefore currently paraphyletic, and its systematic revision is needed. We demonstrate that sequencing the proteome of Early Pleistocene dental enamel overcomes the limitations of phylogenetic inference based on ancient collagen or DNA. Our approach also provides additional information about the sex and taxonomic assignment of other specimens from Dmanisi. Our findings reveal that proteomic investigation of ancient dental enamel-which is the hardest tissue in vertebrates11, and is highly abundant in the fossil record-can push the reconstruction of molecular evolution further back into the Early Pleistocene epoch, beyond the currently known limits of ancient DNA preservation.

Postcranial evidence from early Homo from Dmanisi, Georgia.

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 from Dmanisi comprising a partial skeleton of an adolescent individual, associated with skull D2700/D2735, and the remains from three adult individuals. This material shows that the postcranial anatomy of the Dmanisi hominins has a surprising mosaic of primitive and derived features. The primitive features include a small body size, a low encephalization quotient and absence of humeral torsion; the derived features include modern-human-like body proportions and lower limb morphology indicative of the capability for long-distance travel. Thus, the earliest known hominins to have lived outside of Africa in the temperate zones of Eurasia did not yet display the full set of derived skeletal features.