EXAMINATION OF THE POSTERIOR CUSPS ON THE LOWER CARNASSIAL TO DETERMINE THE AFFINITY OF EXTANT AND FOSSIL PANTHERINE CATS

There is considerable similarity between lion (Panthera leo) and tiger (Panthera tigris) skeletons, which makes them and some of their fossil relatives difficult to distinguish. Manamendra-Arachchi et al. (2005), use the presence of posterior notches on the lower carnassials to determine the affinity of these felids based upon dentition alone. While different authors have used different terminology to describe these structures, their descriptions correspond to the presence of the Metaconid and Talonid cusps on the lower first molar. While the metaconid and talonid cusps are prominent in several families of the order Carnivora, they are greatly reduced in the Felidae, sometimes completely lost. In P. leo there is usually just a talonid, while P. tigris usually has both cusps.

This presentation reports on an ongoing study of these cusps and their phylogenetic significance. While this distinction does work to distinguish extant Lions and Tigers, the degree of difference appears to vary between the subspecies of tigers. The subspecies Panthera tigris tigris often shows these cusps blatantly, while P.t. altaica only shows this trait slightly. All fossil members of the Panthera leo group (P. leo. P. atrox, and P. spelaea) agree with the extant lions in having only one posterior cusp. When looking at some of the other pantherines, the leopard (Panthera pardus) and jaguar (Panthera onca) both generally follow the P. leo pattern of having only a talonid. While the clouded leopard (Neofelis nebulosa), and fossil P. tigris generally follow the tiger pattern of having both cusps. While this trait alone doesn't determine the phylogeny of these cats, it does show patterns that can help clarify their relationships.