Small-mammal postcrania from the middle Paleocene of Walbeck, Germany

Abstract

The fissure fills of Walbeck, northwest of Halle, have produced one of the largest known assemblages of Paleocene vertebrates and the only one of this age from Germany. Nearly 6,000 mammalian specimens have been identified, almost half of which represent small mammals of less than 500 g, the majority probably weighing 350 postcranial elements collected more than 70 years ago. Multiple morphs of most of the major limb bones are represented, the most numerous elements being humeri, femora, tibiae, calcanei, and astragali. A small number of bones are attributable to plesiadapiform primates and to the probably euarchontan Adapisoriculidae, both likely to have been arboreal. The vast majority of elements, however, represent terrestrial micro-mammals, some showing semifossorial adaptations but most indicating cursorial or saltatorial locomotion. Most of these bones probably belong to the most common small mammals from Walbeck (based on teeth): Adapisorex, Walbeckodon, and Prolouisina, which have recently been interpreted as stem macroscelideans. The morphology of these bones supports that interpretation. The predominance of terrestrial mammals and the low species diversity of the Walbeck local fauna suggest that it sampled a relatively open and unstable environment.