Cladistic studies using morphological characteristics have been unable to resolve the phylogenetic position of the American lion. One study considered the American lion, along with the cave lion, to be most closely related to the tiger (Panthera tigris), citing a comparison of the skull; the braincase, in particular, appears to be especially similar to the braincase of a tiger. Another study suggested that the American lion and the Eurasian cave lion were successive offshoots of a lineage leading to a leopard-extant lion clade. A more recent study comparing the skull and jaw of the American lion with other pantherines concluded that it was not a lion but a distinct species. It was proposed that it arose from pantherines that migrated to North America during the mid-Pleistocene and gave rise to American lions and jaguars (Panthera onca). Another study grouped the American lion with P. leo and P. tigris, and ascribed morphological similarities to P. onca to convergent evolution, rather than phylogenetic affinity.