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Area de Paleontología, Dpto. Ciencias de la Tierra, Facultad de Ciencias, Universidad de Zaragoza, 50009 Zaragoza, Spain cuencag{at}unizar.es
The sites of Atapuerca are well known for their hominin-bearing localities of Early to Middle Pleistocene age. Trinchera Dolina yields western Europe’s oldest fossil hominin, the 850 ka Homo antecessor; and at Sima de los Huesos there occurs the best collection of the Middle Pleistocene hominin Homo heidelbergensis. However, small mammals (Rodentia, Insectivora, Chiroptera and Lagomorpha) represent the largest number of species and greatest fossil abundance in the deposits of the Atapuerca cave complex. The small mammals are grouped by habitat categories, but because the ecology of mammals is complex, we base our study on the evolution of these categories throughout the sequence. The assemblage distribution at the Trinchera Dolina site reflects landscape and environmental changes during the past million years. Shifts between woodland, open land and moorland are indicated by the relative abundance of species based on diagnostic elements such as first lower molars. These data are combined with the distribution of large mammals, pollen, sediments and geological context of the Trinchera Dolina site. From this interdisciplinary approach, we conclude that the first hominins from western Europe (Homo antecessor) lived during a warm, wet and wooded interval, probably corresponding to Marine Isotope Stages 21 to 19. The transition from Early to Middle Pleistocene at Atapuerca is characterized by palaeoenvironmental changes recorded between levels TD5–6 and TD8–10, respectively. The general opening of the landscape at the beginning of the Middle Pleistocene could have favoured the dispersal of hominins (Homo heidelbergensis) across western Europe.
