Three new malleodectids (Marsupialia, Malleodectidae) from the late Oligocene and early Miocene deposits of the Riversleigh World Heritage area, northwestern Queensland

Three new malleodectids (Malleodectidae, Marsupialia) are described from late Oligocene and early Miocene deposits of the Riversleigh World Heritage Area, northwestern Queensland. Exosmachus robinbecki gen. et sp. nov. and Chitinodectes wessechresti gen. et sp. nov. share dental synapomorphies with Malleodectes species to the exclusion of other malleodectids. Protamalleus stevewroei gen. et sp. nov. is the most plesiomorphic malleodectid known, retaining several symplesiomorphies shared with plesiomorphic dasyuromorphians and australidelphians. Estimated body masses are 110–155 g (Exosmachus robinbecki), 151 g (Chitinodectes wessechresti), and 226 g (Protamalleus stevewroei). Parsimony phylogenetic analysis supports all new taxa as malleodectids, placing Exosmachus robinbecki as sister to Malleodectes species, Chitinodectes wessechresti as sister to this clade, and Protamalleus stevewroei as sister to all other malleodectids. Barinya wangala is sister to the clade containing Chitinodectes wessechresti, Exosmachus robinbecki and Malleodectes. A Bayesian total evidence analysis places B. wangala, Chitinodectes wessechresti, Exosmachus robinbecki, and Malleodectes within Malleodectidae, but recovers Protamalleus stevewroei as an incertae sedis dasyuromorphian. Morphofunctional analyses suggest Chitinodectes wessechresti and Exosmachus robinbecki were durophagous hypocarnivores like species of Malleodectes species, whereas Protamalleus stevewroei and B. wangala were more generalist carnivores, comparable to Dasyurus viverrinus but with enhanced durophagous capabilities.