Systematic position of the cave lion Panthera spelaea (Goldfuss) based on cranial and dental characters

Well-preserved skulls of Late Pleistocene Panthera spelaea are described from two geographically distant regions of Russia situated in the Russian Plain and Northern Siberia. The resemblance of the studied material with contemporaneous fossil lions from Alaska is established. The cranial morphology of P. spelaea confirms its phylogenetic position within the lion group, whereas many of the characters supporting the cave lion's relationship with the tiger are primitive. Both living and cave lions are advanced relative to the Middle Pleistocene P. fossilis in having larger upper incisors and more inflated bullae. P. spelaea also possesses the following advanced characters in common with the living lion: widened muzzle in the canine and P2 areas, wide nasal bones, relatively short pre-orbital part of the skull, laterally widened mastoid area, V-shaped form of the posterior tip of the frontal process of maxillary bone, and reduced cusp on the protocone bulge of P4. These conditions establish P. spelaea as a distinct species.