The basipodium of Anthracobunodon weigelti HELLER, 1934 (Artiodactyla, Mammalia) from the middle Eocene Geiseltal near Halle (Germany)

Das Basipodium von Anthracobunodon weigelti HELLER, 1934 (Artiodactyla, Mammalia) aus dem mittleren Eozän des Geiseltales bei Halle (Deutschland)

Abstract

The carpus and tarsus are described of the middle Eocene haplobunodontid Anthracobunodon weigelti from the lignite beds of the Geiseltal (MP 13). The study is based on new methods of microradiography and computer-tomography which allow a classic and a three-dimensional investigation of morphological details. The reconstructed morphology of the basipodium is compared with other artiodactyls of the Eocene and interpreted phylogenetically. Anthracobunodon displays a paraxonic foot with typical artiodactyl astragalus and calcaneum. Navicular and cuboid are unfused. An entocuneiform and an ectocuneiform exist distally, which are probably fused with the mesocuneiform. The carpus displays the beginning of the paraxonic arrangement still without any fusion. The carpals are in two rows with four bones each. Five metacarpals are retained, the first of which is reduced to half the length of the others, the third is the longest. In the foot the main metatarsals have about the same length, the first metatarsus is reduced. Both extremities are characterised by hooflike third digits.