The earliest immigration of woolly rhinoceros (Coelodonta tologoijensis, Rhinocerotidae, Mammalia) into Europe and its adaptive evolution in Palaearctic cold stage mammal faunas

摘要

The cold adapted larger mammal faunas of Pleistocene Eurasia (the so-called Mammuthus-Coelodonta faunas) were mainly composed of autochthonous Palaearctic elements. Whereas the history of the immigration and evolution of European woolly mammoths has been exhaustively studied, comparable investigations for woolly rhinoceroses are lacking. Referring to the remains of European and Asian Coelodonta in general and the first skull to be found of a European woolly rhinoceros of early Middle Pleistocene age (from Bad Frankenhausen, Germany) in particular, the occurrence, dispersal, morphological evolution and ecological adaptation of early Coelodonta are reviewed. Coelodonta originated around 2.5 Myr BP north of the Himalayan-Tibetan uplift. The genus was restricted in its range to different types of steppe landscapes of continental Asia for more than two million years and it wasn't until MIS 12, when extended phases of low temperature and aridity prevailed in western Eurasia that woolly rhinoceroses comparable to Coelodonta tologoijensis spread westward towards Central Europe for the first time. Coelodonta entered Central and, in several cases, Western Europe during all of the subsequent Middle to Late Pleistocene cold stages. Morphological evolution, in particular, the elongation and narrowing of the head and successively its lower and more inclined posture, the shift of the orbits towards the rear of the skull, and changes in the position and morphology of the tooth row concurrently indicate progressive adaptations to an efficient grazer. During the course of their Plio-/Pleistocene evolution, Coelodonta rhinoceroses changed strikingly from cursorial mixed feeders of central Asian origin to graviportal, highly specialised grazers, inhabiting huge belts of tundra-steppe-like environments during dry and cool to cold periods, and thus becoming the only rhinocerotid to join the Eurasian mammoth faunas. The Bad Frankenhausen Coelodonta record dates the initial formation of a pan-Eurasian Mammuthus-Coelodonta faunal complex to about 460 kyr BP.