page_title: American lion
section_title: Taxonomy and evolution
hierarchical_section_title: American lion / Taxonomy and evolution
caption_attribution_description: An illustration of the holotype lower jaw of Panthera "Felis" atrox described by Leidy. From Leidy, 1852.
context_page_description: The American lion, also known as the "North American lion", or "American cave lion", is an extinct pantherine cat that lived in North America during the Pleistocene epoch and the early Holocene epoch, about 340,000 to 11,000 years ago.
  Its fossils have been excavated from Alaska to Mexico. Genetic analysis has shown that the American lion and the Late Pleistocene Eurasian cave lion are sister lineages.
  It was about 25% larger than the modern lion, making it one of the largest known felids.
context_section_description: The American lion was designated by American paleontologist Joseph Leidy as Felis atrox in 1853. Hemmer proposed the trinomen Panthera leo atrox in 1974, which was later supported by Kurten in 1985.
  The American lion was initially considered a distinct species of Pantherinae, and designated as Panthera atrox /ˈpænθərə ˈætrɒks/, which means "cruel" or "fearsome panther" in Latin. Some paleontologists accepted this view, but others considered it to be a type of lion closely related to the modern lion (Panthera leo) and its extinct relative, the Eurasian cave lion (Panthera leo spelaea or P. spelaea). It was later assigned as a subspecies of P. leo (P. leo atrox) rather than as a separate species. Most recently, both spelaea and atrox have been treated as full species.
  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.
  However, mitochondrial DNA sequence data from fossil remains suggests that the American lion (P. atrox) represents a sister lineage to the Eurasian cave lion (P. spelaea), and likely arose when an early cave lion population became isolated south of the North American continental ice sheet about 340,000 years ago. The most recent common ancestor of the P. atrox lineage is estimated to have lived about 200,000 (118,000 to 346,000) years ago. This implies that it became genetically isolated from P. spelaea before the start of the Illinoian glaciation; a spelaea population is known to have been present in eastern Beringia by that time, where it persisted until at least 11,925 ± 70 years ago. This separation was maintained during the interstadials of the Illinoian and following Wisconsin glaciations as well as during the Sangamonian interglacial between them. Boreal forests may have contributed to the separation during warmer intervals; alternatively, a reproductive barrier may have existed.
  The study also indicates that the modern lion is the closest living relative of P. atrox and P. spelaea. The lineages leading to extant lions and atrox/spelaea were thought to have diverged about 1.9 million years ago, before a whole genome-wide sequence of lions from Africa and Asia by Marc de Manuel et al. showed that the lineage of the cave lion diverged from that of the modern lion around 392,000 – 529,000 years ago.
caption: Illustration of the type specimen from Leidy, 1852
exif: {}