Macropodoid endocranial casts from the early Miocene of Riversleigh,northwestern Queensland

Two macropodoid endocranial casts from the early Miocene of the Riversleigh World Heritage Area, northwestern Queensland are described. The larger is associated with a fragmentary cranium and is attributable to the balbarine kangaroo Balbaroo. The smaller more complete specimen was found as an isolated endocast and cannot be confidently identified beyond superfamily level. The external neurocranial morphology of both specimens closely resembles that of plesiomorphic macropodoids and indicates a basal ‘macropodid-grade’ level of complexity. Development of the visual region of the neocortex suggests that crepuscular-nocturnal habits might have been present in early Miocene kangaroos.