Descriptions of koala fossils from the Miocene of Riversleigh, northwestern Queensland and implications for Litokoala (Marsupialia, Phascolarctidae)

Litokoala is revised on the basis of new material from the early to middle Miocene deposits of Riversleigh. A new species of Litokoala is described from the System B Outasite Local Fauna. Litokoala garyjohnstoni sp. nov. possesses a unique combination of both plesiomorphic and apomorphic dental features, making its phylogenetic position within Litokoala difficult to interpret. In some aspects of dental morphology, L. garyjohnstoni is convergent on the early Miocene phascolarctid Nimiokoala greystanesi Black & Archer, 1997. The dentition of a partial skull of Litokoala from Jims Carousel Site, System C is also described. On the basis of this dentition, it is suggested that the morphological variation between L. kutjamarpensis Stirton, 1967 and L. kanunkaensis Springer, 1987 does not warrant specific distinction, the latter being the junior synonym.