Palaeoenvironmental and taphonomical study based on the microvertebrate assemblages of three upper pleistocene cave sites from Mani and central Greece

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Κολενδριανού, Μαρία
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The present thesis is a discussion of the palaeoenvironmental conditions in the wider area of Kythros islet (Lefkas) and Mani Peninsula (Peloponnese) during the last hundred thousand years, based on the taxonomic determination of microvertebrate fossil material from three cave sites: Panthera cave (Kythros islet, Inner Ionian Archipelago, central Greece), Kalamakia cave and Melitzia cave (Mani Peninsula, Peloponnese). The taphonomical history of these caves was also reconstructed with regard to the assemblages’ agent of accumulation and the post- depositional processes they went through. In this context, 74916 teeth and skeletal elements from amphibians, lizards, snakes, insectivores and rodents were examined from the three Upper Pleistocene cave sites, in what was the first attempt to apply taphonomical indices for the identification of predators and taphonomical processes and to conduct palaeoenvironmental reconstructions using the Taxonomic Habitat Index (THI) upon microvertebrate palaeontological material from Greece and the southern Balkans. 62 taxa and 2388 individuals were identified in all three sites with Melitzia being the richest and Panthera cave the poorest in both species richness and individual abundance. Herpetofauna was the most diverse animal group, but rodents were the most numerically abundant animal group in every cave. Out of the taxa identified for all three cave sites, 16 are reported for the first time in the Greek fossil record, 2 are reported for the first time in mainland Greece and 10 are reported for the first time in Upper Pleistocene deposits. Regarding the palaeoenvironmental analysis, the reconstructions revealed the existence of mixed habitats varying between relative expansions mainly of shrublands, grasslands, deciduous forests and rocky areas with the occasional presence of water bodies of a local character in the caves’ wider areas. There were no major shifts between the percentages of different habitats but those that were detected could be correlated with climatic events within a geochronological context (Kalamakia, Melitzia). However, local factors and/ or site taphonomy are also believed to have affected the analyses to some extent. Consequently, it is suggested that- in the future- these palaeoenvironmental reconstructions should be complemented by palaeoclimatic analyses and interpreted in conjunction. Concerning taphonomy, the most common agent of microvertebrate accumulation was predation, since digestion was always present in every unit of every site in the present study. Different predators were identified in every site while, in some cases, predation by multiple predators is believed to have taken place simultaneously or successively. In Panthera cave, assemblages are believed to have been formed by category 3-4 mammalian or owl predators in the lowermost unit, while the uppermost units seem to have been significantly affected by post- depositional processes that either affected the signature(s) of the accumulating agent(s) beyond identification (unit 1) or caused the accumulation of material themselves (water transport in unit 0). In the case of Kalamakia, barn owls were the accumulative agents while for Melitzia category 3 and 4 predators were responsible for the accumulation of microvertebrate material (mixed with predation by category 1-2 predators in some units). Other than digestion, additional alterations were identified in the sites that were related to post- depositional natural processes occurring in a cave (black staining by water dripping, weathering, cave corrosion, rootmarks) or caused by the human or animal residents of the caves (burning, trampling). These processes seem to have significantly affected some of the results and interpretation efforts of the present study, either directly by altering the preservation state of the material or indirectly by producing inconclusive results. In both cases, the introduced biases were taken into consideration during interpretations. Moreover, palaeozoogeographical implications regarding the identification of 10 taxa that were found to be outside their modern geographical ranges were considered, regarding previous identifications in the Greek fossil record. Possible corridors of dispersal are, therefore, proposed based on the Greek relief and the water bodies that could have acted as barriers during the animals’ descent southwards/ ascent northwards. Finally, rare dental phenotypic anomalies on the occlusal surface of Microtus molars were identified that may be considered as a hint of closed breeding and bottleneck events in the beginning and at the end of the last glacial period, cautiously adding further information into the already complex phylogeographic history of the genus, since these rare traits are only an indication of said processes.
Fossils, Taphonomical indices, Palaeoenvironmental analysis, Palaeozoogeography, Peloponnese, Microtus