PEDAL MORPHOLOGY OF THE MARSUPIAL LION THYLACOLEO CARNIFEX (DIPROTODONTIA: THYLACOLEONIDAE) FROM THE PLEISTOCENE OF AUSTRALIA

摘要

Thylacoleo carnifex, the so-called marsupial lion, is arguably the most enigmatic of all Australia’s extinct marsupials. It was the last and most derived member of an entire family of extinct marsupials that included the small Oligo-Miocene form Priscileo and the Oligo-Miocene dog-sized species of Wakaleo. Dog to lioness-size Plio-Pleistocene species of Thylacoleo were the largest and principal mammalian carnivores of the Australian late Cenozoic and among the most widely distributed of the so-called megafauna species. Clearly derived from a diprotodontian ancestry, species of Thylacoleo have evolved to hyper-carnivory through pronounced development of upper and lower third premolars as extreme carnassials with a concomitant reduction in the molar tooth row. Paralleling these changes has come a foreshortening and broadening of the palate along with frontation of the orbits to produce a skull architecture reminiscent of felids, no doubt giving rise to Owen’s ‘lion’ analogy (Owen, 1871). Paradoxically they retain the diprotodontian incisor configuration to form an almost parrot-like beak while the upper canines persist as vestigial stumps within a very short diastema (Wells, Horton and Rogers, 1982).