American Lion

The term "American lion" has sometimes been used to mean the cougar.

This article is about the feline. For the Pulitzer-winning biography, see American Lion (book).

American Lion Temporal range: Pleistocene
Skeleton from the La Brea tar pits
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Carnivora
Family:	Felidae
Genus:	Panthera
Species:	†P. atrox Leidy, 1853

The American lion (Panthera atrox) — also known as the North American lion, Naegele’s giant jaguar or American cave lion — is an extinct feline of the family Felidae, endemic to North America during the Pleistocene epoch (1.8 mya to 11,000 years ago), existing for approximately 1.79 million years.^[1] While it was once considered a subspecies of lion closely related to the Eurasian cave lion (Panthera leo spelaea),^[2] later study showed that it was not in fact a true lion and cannot be assigned to any modern species of cat.^[3]

The American lion was one of the largest types of cat ever to have existed, slightly larger than the Early Middle Pleistocene primitive cave lion, P. leo fossilis and about twenty-five percent larger than the modern African lion.^[4]

Description

Restoration of an American Lion

The American lion is an extinct animal which originated in North America and went on to colonize part of South America as part of the Great American Interchange. The head-body length of the American lion is estimated to have been 1.6–2.5 m (5 ft 3 in–8 ft 2 in) and it would have stood 1.2 metres (4 ft) at the shoulder.^[5] Thus it was smaller than its contemporary competitor for prey, the Giant short-faced bear, which was the largest carnivoran of North America at the time. The American lion was not as heavily built as the saber-toothed cat Smilodon populator, which may have weighed up to 360–470 kilograms (790–1,000 lb).^[6] Sorkin (2008) estimated it to weigh roughly 420 kilograms (930 lb),^[7][8] but new estimations show a top weight of 351 kg (774lbs.) for the largest specimen and an average weight for males of 255.65 kg (563lbs.).^[9]

Approximately one hundred specimens of American lions have been recovered from the La Brea Tar Pits, in Los Angeles, so their body structure is well known. The features and teeth of the extinct American lion strongly resemble modern lions, but they were considerably larger. The American lion was once believed to be the largest subspecies of lion.

Range

South of Alaska, the American lion first appeared during the Sangamonian Stage (the last interglacial). After that it was widespread in the western Americas from Alaska to Peru. It was absent from most of eastern North America and peninsular Florida,^[5] although it may have been present in the Lake Michigan area. Like many other large mammals, it went extinct at the end of the Pleistocene, about 10,000 years ago. By then the American lion was one of the abundant Pleistocene megafauna, a wide variety of very large mammals who lived during the Pleistocene. Remains are most common in the Yukon and from the La Brea Tar Pits.

Environment

Skull at the National Museum of Natural History

In some areas of its range, the American lion lived under cold climatic conditions. They probably used caves or fissures for shelter from the cold weather.^{[citation needed]} They may have lined their dens with grass or leaves, as the Siberian tiger does, another great cat that currently lives in the north.^[10]

There are fewer American lions in the La Brea tar pits than other predators such as saber-toothed cats (Smilodon fatalis) or dire wolves (Canis dirus), which suggests they may have been smart enough to avoid the hazard.^[4] American lions likely preyed on deer, North American horses (now extinct), North American camels, North American tapirs, American bison, mammoths, and other large, herbivorous animals.^[11][12]

This species disappeared about the same time as other species during the Holocene extinction event, which wiped out likely prey of megafauna. Bones of the lion have been found in the trash heaps of Paleolithic American Indians, so human predation may have contributed to their extinction.^[13]

A replica of the jaw of the first specimen of American lion discovered can be seen in the hand of a statue of paleontologist Joseph Leidy, which is currently standing outside the Academy of Natural Sciences in Philadelphia.

Classification

Reconstruction of the American Lion

The American lion was initially considered a distinct species of Pantherinae, with the scientific name Panthera atrox ( /ˈpænθərə ˈætrɒks/), which means "cruel" or "fearsome panther" in Latin). Overall the skull of the extinct cat was most like that of the jaguar (P. onca). Some later authors accepted this view, but other experts considered P. atrox most closely related to the African lion (P. leo) and its extinct Eurasian relative, the cave lion (P. spelaea). Later paleontologists assigned the extinct American cat as a subspecies of P. leo, ("P. leo atrox") rather than as a separate species. At least one authority considers the American Lion (along with its closest relative, P. spelaea), to be more closely related to the tiger, P. tigris, citing a comparison of skull shapes; The braincase, in particular, appears to be especially similar to the braincase of a tiger. ^{[14][Full citation needed][15][16]}

Illustration of the type specimen from Leidy, 1852

Genetic evidence from remains of P.atrox from Wyoming and Alberta shows that the American lion is the sister clade of P. spelaea, with a some degree of statistical support.^[2] Cladistic studies using morphological characteristics have been unable to resolve the phylogenetic position of the American Lion.^[16][3] In the first study, the American Lion was grouped with a clade consisting of the extant Lion and the Leopard.^[16] This result was contradicted by the second study that compared the skull, jaw, and teeth of P. atrox with other pantherines and concluded that "P. atrox was no lion" and was distinct from all extant species. The authors suggested that P. atrox may have arisen from pantherines that migrated into North America in the mid-Pleistocene Epoch and also gave rise to jaguars.^[3]

See also

	Extinction portal
	Paleontology portal
	Prehistoric mammals portal

• Panthera leo vereshchagini, the East Siberian or Beringian cave lion.

References

1. ^ http://dinosaurs.about.com/od/mesozoicmammals/p/American-Lion-Panthera-Leo-Atrox.htm
2. ^ ^{a b} Barnett, Ross et al. (2009): Phylogeography of lions (Panthera leo ssp.) reveals three distinct taxa and a late Pleistocene reduction in genetic diversity (PDF) Mol. Ecol. Vol.18, p.1668-1677.
3. ^ ^{a b c} Christiansen, Per, & Harris, John M. (2009). "Craniomandibular Morphology and Phylogenetic Affinities of Panthera atrox: Implications for the Evolution and Paleobiology of the Lion Lineage". Journal of Vertebrate Paleontology 29 (3): 934–945. doi:10.1671/039.029.0314. 
4. ^ ^{a b} Tom Demere. "SDNHM Fossil Mysteries Field Guide: American lion". http://www.sdnhm.org/exhibits/mystery/fg_lion.html. Retrieved 2010-05-18. 
5. ^ ^{a b} Paul S Martin (1984). Quaternary Extinctions. The University of Arizona Press. ISBN 0-8165-1100-4. 
6. ^ Christiansen P, Harris JM (2005) Body size of Smilodon (Mammalia: Felidae). J Morphol 266: 369–384
7. ^ Sorkin, B. 2008: "A biomechanical constraint on body mass in terrestrial mammalian predators". Lethaia, 41, pp 333–347
8. ^ Merriam, J.C. & Stock, C. 1932: The Felidae of Rancho La Brea. Carnegie Institution of Washington Publications 442, 1–231.
9. ^ Christiansen & Harris 2009
10. ^ http://www.beringia.com/research/lion.html
11. ^ arkgelbart.wordpress.com/2010/07/28/panthera-atrox-what-kind-of-cat-was-it/
12. ^ http://www.beringia.com/research/lion.html
13. ^ http://dinosaurs.about.com/od/mesozoicmammals/p/American-Lion-Panthera-Leo-Atrox.htm
14. ^ Groiss, 1996.
15. ^ Burger, Joachim et al. (2004): Molecular phylogeny of the extinct cave lion Panthera leo spelaea. (PDF) Mol. Phylogenet. Evol. Vol.30, p.841-849.
16. ^ ^{a b c} Christiansen, Per (December 2008): "Phylogeny of the great cats (Felidae: Pantherinae), and the influence of fossil taxa and missing characters" Cladistics Vol.24, Nu.6,pp. 977-992(16)

External links

• Prehistoric cats and prehistoric cat-like creatures, from the Messybeast Cat Resource Archive.
• ^{[dead link]}, by C. R. Harrington, from Yukon Beringia Interpretative Center.
• Panthera Atrox in Cryptozoology