Due to its unique predatory morphology, scientists repeatedly claim Thylacoleo to be the most specialised mammalian carnivore of all time.[8] Thylacoleo had vertical shearing 'carnassial' cheek teeth that are relatively larger than in any other mammalian carnivore.[2] Thylacoleo was clearly derived from the diprotodontian ancestry due to its incisor morphology and is distinguished by the pronounced development of upper and lower third premolars which functioned as extreme carnassials with complementary reduction in the molar teeth row.[9] They also had canines but they served little purpose as they were stubby and not very sharp.[10]