A new genus of dasyurid Miyumba chrisdickmani (Marsupialia, Dasyuridae) from the Early Miocene deposits of the Riversleigh World Heritage Area, north-western Queensland

This study describes Miyumba chrisdickmani gen. et sp. nov., a new genus and species of dasyurid (Marsupialia, Dasyuridae) from Early Miocene deposits of the Riversleigh World Heritage Area in north-western Queensland. This taxon, similar in size to extant species of Antechinus and Sminthopsis (23–33.5 g), is the oldest and most plesiomorphic member of the family Dasyuridae. Character analysis identifies one new lower dental synapomorphy for Dasyuridae that previously lacked any dental synapomorphies uniting the family. Parsimony and Bayesian phylogenetic analysis supports the placement of M. chrisdickmani as the sister taxon to all other dasyurids. These analyses also recover the diminutive Mayigriphus orbus from early Late Miocene deposits of Riversleigh either as a sminthopsine dasyurid or as the second most plesiomorphic member of the family after M. chrisdickmani. Joculusium muizoni from Riversleigh’s Middle Miocene deposits was recovered outside Dasyuridae as a sister taxon by both phylogenetic analyses. Urrayira whitei was recovered by both analyses as a member of the dasyurid genus Planigale, whereas Antechinus yuna and Antechinus yammal were supported as species of Antechinus. Morphological similarity of M. chrisdickmani to extant dasyurids from New Guinea suggests a possible close phylogenetic relationship between these lineages and may represent yet another remnant New Guinean group of rainforest-adapted marsupials that had its origins in the Miocene rainforests of Riversleigh.