Abstract

Water voles are important key fossils of the Quaternary. Given their wide distribution, regional differences were expected to exist in different areas. Early hints on possible independent evolutionary trends of water voles in Italy came from palaeontology and specifically from the comparison of enamel differentiation (SDQ value) of the first lower molars between specimens from Italy and Germany. The data available at that time indicated that in the early Middle Pleistocene there were only minor enamel differences between first lower molars of water voles from these two geographical regions, whereas from the late Middle Pleistocene onwards, two lineages were clearly distinguished. Examination of mitochondrial DNA of extant Arvicola populations from across Europe by Wust-Saucy led to a similar conclusion that Arvicola populations from the Italian Peninsula had undergone independent evolution during the last 0.2 million years.

The inclusion of new fossil and extant Arvicola samples from Italy and Central Europe, together with the examination of additional morphological parameters of the occlusal surface (so-called van der Meulen indexes), have provided further support for the proposed evolutionary pattern. The combined analysis of length, SDQ and A/L index reveal a certain degree of intercorrelation and indicate an essentially continuous evolutionary trend. However, variations are discernible, related to the age and geographical origins of the samples, and become more clearly seen at least since the beginning of the Late Pleistocene. Italian samples have a characteristic tendency to grow larger, elongate the anteroconid, and have less derived SDQ. This corroborates the suggestion that Italian water voles underwent an evolutionary history distinct from that of their Central European counterparts. The differences in morphology may be related to a combination of etho-/ecological (aquatic or terrestrial habits) and palaeobiogeographical factors.

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Abstract

The Middle Pleistocene site Bilzingsleben II is well-known for its wealth of vertebrate and archaeological remains. Of particular importance is the record of Homo erectus bilzingslebenensis. Most palaeontologists consider the find horizon as a primary vertebrate deposit formed during human occupation, while some archaeologists attribute its formation to turbulent gravitational mass flows, inundation or a combination of both. Here we present mortality profiles of the beavers Castor and Trogontherium to provide further arguments to this controversial discussion. The mortality profiles of Castor from Bilzingsleben II, Weimar-Ehringsdorf and Weimar-Taubach are largely identical indicating similar taphonomic filters that were effective in the formation of the find layers. Individuals, which were tentatively classified as suspected ±2–2½ year old beavers dominate by far in all three sites. The structure of these mortality profiles shows similarities to Stiner’s (1990) “prime dominated mortality pattern”, which is indicative of human hunting. This consideration is supported by the difference of the mortality profile of Trogontherium from Bilzingsleben II (dominance of older individuals) in relation to the profiles of non-hominin generated assemblages of Tegelen and Mosbach 2 (dominance of younger individuals). Thus, our data support the interpretation of the Palaeolithic find horizon of Bilzingsleben II as a primary vertebrate deposit, but not the gravitational mass flow and inundation hypotheses.

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