TAXONOMY & NOMENCLATURE * *How Do We Know This? Like living animals, fossil remains of once-living animals
classified and grouped according to their relationships
each other and to their ancestors.
(Barry 1987) (Burger et al 2004) (Leidy 1853) (Turner 1987 & 1997) (Wozencraft 2005)
Describer (Date): Leidy 1853 for Panthera atrox. American Philosophical Society Transactions 10:319-321
Extinct Pleistocene lions from North America may be genetically distinct enough to be a separate species (Panthera atrox), or they may instead be a subspecies of the modern lion, Panthera leo (Panthera leo atrox). Both taxonomies are used. (Leidy 1853) (Turner 1997) (Burger et al 2004)
Common name: American Lion
Scientific Name: "Panthera" may be traced to Sanskrit for tiger, or "pundarikam" which was then altered to a Greek sounding word; "leo" means lion in Latin; "atrox' means cruel or frightful in Latin
Genetic studies split all living cats into eight clusters of species with lions grouped with other Panthera. (Johnson et al 2005)
Domestic cat lineage
Leopard Cat group
Bay Cat group
Earliest fossils of the Panthera genus date to 3-4 million years ago from Tanzania (Barry 1987) (Turner 1997)
Panthera atrox was the North American (and northern South American) cave lion during the Pleistocene;
other cave lions at the time lived in Europe and Siberia
These cave lion lineages were isolated from African and Asian lions since at least 600,000 years ago, according to DNA data (Burger 2004)
Cave lion lineages are "highly distinct" genetically from the living lion (Burger 2004)
The last North American lions became extinct around 13,000 calendar years ago along with mammoths and many other large mammals.
Panthera leo, the African lion, is the only surviving lion; of eight recognized subspecies, two are believed extinct in the wild.
PREHISTORIC DISTRIBUTION & HABITAT * *How Do We Know This? Paleontologists use knowledge of the earth's rocks, global
plate tectonic movements,
ancient ecosystems, and the chemical process of fossilization
to make sense
of fossil distribution patterns and ancient habitats.
(Barry 1987) (Cerling et al 1998) (Gilbert & Martin 1984) (Jefferson2001) (Kurtén 1968)
No other mammal (with the exception of humans today) has ever had such a wide distribution as the extinct lions in the Panthera lineage.
During the Pleistocene Epoch which ended about 11,500 years ago, lions occupied most of Africa, Europe, Asia, North America, and northern South America
Panthera atrox, the extinct American Lion, ranged from Alaska to Peru but was absent in northeastern Canada and U.S. and southern Florida
P. atrox fossils found in U.S. states of California, Texas, Idaho, Nevada, Nebraska, Mississippi, and northern Florida
Large concentration of Panthera atrox fossils discovered at Rancho La Brea's asphalt deposits in Los Angeles
Over 80 individuals trapped
as they sought prey animals stuck in pools of tar (Jefferson 2001)
Many other species of extinct predators, including Smilodon fatalis were trapped along with P. atrox
Seems to have occupied open country rather than forests
Evolution of the Panthera cats coincides with evolution of open grassland plant communities of C-4 plants (Barry 1987) (Cerling et al 1998)
Adaptation to open country may have allowed lions over time to move into North America from Asia across treeless expanses of tundra
Slender but powerful legs of this great lion aided pursuit in open country
P. atrox probably occupied steppe tundra and mountain conifer/grasslands ecosystems (Gilbert & Martin 1984) .
Natural Trap Cave in Wyoming and other sites with P. atrox fossils had associated fossils of animals that still live in steppe tundra and mountain grassland habitats today
PHYSICAL CHARACTERISTICS* *How Do We Know This? Study of fossil bone and tooth anatomy yields much
about placement and strength of muscles, tendons, ligaments,
nerves, and blood vessels.
In rare cases, skin and hair impressions or actual skin or hair
Body weight is more difficult to gauge because fat leaves no impression
on the skeleton.
A few extinct Pleistocene lions were painted by observant paleolithic artists.
Estimated Body Weight: Large male up to 235 kg (518 lbs); large female up to 175 kg (386 lbs); estimated to be 25 % larger than modern lions. (Anderson 1984) Head and Body Length: 1.6 - 2.5 m (5.3 - 8.2 ft) (Shaw 2005) Tail Length: .5 - .8 m (1.7 - 2.7 ft) (Shaw 2005)
Very similar to modern lions, but larger, with relatively longer and stronger legs
Larger brain, relative to size, than seen in the Smilodon that lived at the same time
Used exclusively for meat-eating
Males' canine teeth 20% larger than females' (Kurtén 1985)
Strength of bite focused at canines
Cro-Magnon people in France painted detailed portraits of lions on cave walls around 30,000 years ago.
Lions were depicted without manes (Clottes 2003)
Observant artists even drew black dots at base of the lions' whiskers (Turner 1997)
Manned lions may have replaced earlier mane-less lions at the end of the Pleistocene (Yamaguchi 2004)
Not known whether the American Lions were spotted (leopard-like) or more uniform in color
Males consistently larger than females; males have larger canine teeth than females (Yamaguichi 2003)
Not known with certainty whether extinct lions had manes, which in modern lions is an important sexual signal (Yamaguichi 2003)
Level of sexual dimorphism similar to or slightly greater than in modern P. leo (Meachen-Samuels & Binder 2009)
Other Physical Characteristics
Flexible and powerful front limbs
Bending strength of Panthera atrox forelimbs much greater than modern lion's and similar to a brown bear's (Anyonge 1996)
These traits helped them to subdue their prey before inflicting a powerful canine killing bite
To some degree all cats have these traits, but they are extreme in several large Pleistocene felids
Like all cats, retractable claws
BEHAVIOR & ECOLOGY* *How Do We Know This? Since direct observation of a fossil animal's behavior isn't
comparison and contrast with living animals for guidance.
Tracks can sometimes
reveal further clues to behavior. At a fossil site, the mix of plant and animal
species gives clues to the ecosystem of that time
(Jefferson 1992, 2001) (Van Valkenburgh & Hertel 1993) (Yamaguchi et al 2004)
Pleistocene lions assumed to be social because of skeletal differences between sexes
Males have large canines
Males have prominent midline crest on the skull
Modern lions with these traits have breeding system with much competition between males
Pleistocene lions assumed to be solitary
because of roughly equal numbers of male and female P. atrox at La Brea Tar Pits
Statistics (128 males vs 100 females) suggest either solitary hunting or hunting by pairs, not prides (Jefferson 2001)
When lions were painted by paleolithic artists, they were sometimes depicted in groups, as with social females today.
Genetic studies suggest modern lions arose from a single population of maned individuals that replaced older mane less
Pleistocene populations (Yamaguchi et al 2004)
Mane-less lions, however, could have been social before manes evolved.
These large cats were keystone species in their habitats, like lions today
Competition with other large predators such as saber-toothed cats and giant bears more intense
than between large carnivores today.
Frequency of fossils tooth breakage suggests this pattern (Van Valkenburgh & Hertel 1993)
P. atrox extinction probably a due to combination of climate change and ecosystem disruption
by paleolithic humans
DIET & FEEDING* *How Do We Know This? Clues to fossil mammals' diets come from teeth,
skull shape and the positions and strength of major jaw muscles, from fossilized
dung and guts, from oxygen isotopes
in bone and teeth,
and from diets of similar
(Guthrie 1990) (Martin & Klein 1984) (Owen 2002) (Therrien 2005) (Van Valkenburgh and Hertel 1993)
All cats, from lions to house cats are hyper-carnivores, with teeth suited for a diet of meat and nothing else.
Have no molars specialized for chewing their food like dogs or bears.
Jaws, like those of modern lions, could kill by closing around the throat or muzzle of their prey
(Owen 2002) (Therrien 2005)
Extinct American lions' jaws concentrated their forces at the canine teeth
Strength of bite greater than that of modern lions
Strong incisor teeth in front of jaw could strip flesh from bone
Carnassial teeth in rear used to slice flesh, not chew bone
Panthera atrox's long legs were ideal for pursuit of prey (Martin and Klein 1984)
Probably fed on horses and deer, camels, ground sloths, young mammoths, and bison in North America.
These animals are size equivalents of prey for lions in the wild today.
Claw and tooth marks on a mummified steppe bison's skin indicate P. atrox killed with techniques like modern lions (Guthrie 1990)
Tooth fracture frequencies of P. atrox suggest to paleontologists that competition was fierce with other predators for prey
(Van Valkenburgh & Hertel 1993)
Extinct lions may have consumed more of their carcasses' bony parts due to this competition.
REPRODUCTION & DEVELOPMENT * *How do We Know This? Clues to stages of development in
a growing animal
replacement patterns and timing of suture closure in skull
and limb bones.
(Feranec 2004) (Therrien 2005)
Life Stages/Growth Patterns
Juvenile Panthera atrox have canine teeth not yet used to kill prey;
they feed on adults' kills
The two halves of the lower jaws are not yet reinforced at the midline symphysis to withstand the force of a killing bite (Therrien 2005)
Growth rates for canine teeth of Panthera atrox were about 2-3 mm (.08 to 1.2 in)/month (Feranec 2004)
Mortality and Extinction
No know predators on adult American Lions
Accidents, fights, hunting by Paleolithic humans
Extinction of Panthera atrox around 13,000 years ago
DISEASES AND PATHOLOGY*
*How do We Know This? Abnormalities in fossil bones may show
evidence of arthritis, cancer, nutritional stress, fractures and more.
Flattened and reduced incisors in a fossil P. atrox lower jaw from Alaska is perhaps a result of old age (Whitmore & Foster 1967) or is a regional genetic difference from lions further south (Beebe & Hulland 1988)
Trauma from fights may have caused bone remodeling seen in two jaw specimens from Alaska (Beebe & Hulland 1988)
Tooth breakage (from possible fights with other predators) three times more common than in lions today (Van Valkenburg & Hertel 1993)
A P. atrox from natural Trap Cave in Wyoming
had extensive abnormal bone growth on its left knee and unusually heavy wear on its canine and incisor teeth (Rothschild & Martin 2003)
Probably this animal was forced to scavenge as a result of its disabling pathology.
Important Web Resources (including where to view fossils in museums):
George Page Museum at La Brea Tar Pits(affiliated with Los Angeles County Museum): Web site has virtual exhibits and information on of an array of Pleistocene fossils. Page Museum exhibits exceptionally well-preserved fossils from the tar pits. A complete fossil skeleton of Panthera atrox is on permanent exhibit.
San Diego Natural History Museum's Fossil Field Guide: Web site with major Pleistocene mammals (and fossils from other time periods) from California described and illustrated. The museum exhibits several Pleistocene fossils, casts, and original models of Pleistocene animals together with seven original murals of Pleistocene plants and animals from southern California.
A life-sized model of Panthera atrox is displayed along with a bronze cast of an actual Panthera atrox skull.
University of Texas Digimorph Project: An annotated collection of images from a large collection of skulls of living and fossil animals. Applet, Slices and 3D Models plus 3D Volume Rendered Movies show skulls from several perspectives. The modern lion, Panthera leo, is featured with both an adult and a juvenile skull.