Australian Marsupial Carnivores: Recent Advances in Palaeontology

Over the last two decades, the study of new fossil material has yielded major insights into the evolution of Australia's marsupial carnivores. This material includes the first complete or nearcomplete crania for Tertiary representatives of Dasyuridae, Thylacinidae and Propleopinae (Hypsiprymnodontidae), as well as the first skulls known for the thylacoleonid genera, Priscileo and Wakaleo. Also of significance has been the discovery of a new species of marsupial carnivore, Djarthia murgonensis, from the Early Eocene Tingmarra local Fauna. Regarding dasyuromorphian evolution, the study of well-preserved material from OligoceneMiocene deposits of Riversleigh has been particularly illuminating. Many findings have been unanticipated. For example, it is now clear that during the early and middle Miocene, the now ubiquitous dasyurids were rare, while the recently extinct Thylacinidae were unexpectedly diverse. Furthermore, at present there is no hard evidence for the existence of any extant dasyurid genera or subfamily greater than Pliocene in age. The oldest confirmed dasyurid is from early to middle Miocene deposits and forms a sister clade to the three living subfamilies. Moreover, it is argued that dasyurids are highly specialised among dasyuromorphians, particularly with respect to their basicranial morphology and not 'primitive' Australian marsupials as has often been supposed. On the other hand, from results of analysis of late Oligocene-Miocene cranial material, k is now evident that Thylacinidae constitutes a very conservative lineage with the recently extinct Thylacinus cynocephalus little more derived than some late Oligocene-Miocene taxa regarding either cranial or dental features. Propleopinae (giant ratkangaroos), previously known only from dental remains, are now represented by two skulls. Interpretation of this evidence supports the hypothesis that at least some species included significant amounts of meat in their diets, while phylogenetic analysis hints at the possibility of a special relationship with balbarines. With respect to Thylacoleonidae, the study of cranial material leaves the issue of the family’s ordinal level affinities uncertain, while the previously accepted tenet that Wakaleo could not be ancestral to Thylacoleo is also questioned. On the basis of dental evidence to hand, the Early Eocene Djarthia murgonensis can not be placed in any marsupial clade with confidence. Thus, biogeographic scenarios excluding the possibility that ameridelphians ever colonised Australia are considered premature. Growing evidence for a diversity of marsupial carnivores in pre-Pleistocene Australia is considered to diminish, if not contradict the argument that the continent's large terrestrial carnivore niches have long been domi-