Priscileo ("Ancient Lion") is the basal-most genus of Thylacoleonidae. Fossils of this genus have been found in Oligocene and Miocene strata of South Australia and Queensland. It was about the size of a possum and was less powerful than the other marsupial lions. The two species have crushing molar teeth (as in omnivorous kangaroos) as well as carnassial blades (large, flesh cutting teeth derived from the first lower molar and last upper molar). The Early Miocene species of P. roskellyae may have been an arboreal species.