Djaludjangi yadjanasp. nov. represents a previously unknown genus of petauroid possum from Riversleigh in northwestern Queensland. Of known phalangeridansDjaludjangimost closely resembles the Petauridae, but lacks synapomorphies previously used to define that family. Although considered likely a plesiomorphic petaurid,D. yadjanais referred here to Petauroidea:incertae sedis, pending comprehensive revision of phalangeriform dental character state distributions. Small possum diversity at Riversleigh indicates a complex and finely partitioned environment such as that found in present-day tropical forests; the discovery at Riversleigh of Australia's first Tertiary dactylopsiline species also argues for a rainforest palaeohabitat.