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.
(Barnett 2005) (Hunt 1996) (Janczewski et al 1992) (Shaw and Cox 2006) (Turner 1997) (Wilson & Reeder 2005)
Describer (Date): Lund, 1842 for Smilodon; Leidy 1868 for Smilodon fatalis
Some genetic and anatomical studies put Smilodon in a sub-family (Machairodontinae), distinct from all modern cats (Barnett et al 2005) (Turner 1997)
Other classifications place Smilodon with the modern cats in Felidae (Janczewsi 1992)
Smilodon comes from the Greek word for "blade" or "chisel" and the Greek word for "tooth"
'Saber tooth' cat refers to the blade or knife-like canine teeth of this fossil felid
Often mistakenly referred to as tigers; aren't closely related to modern tigers
Cats with saber-like canines evolved in several lineages, mostly during the last 10 million years
Smilodon's direct ancestor was Megantereon, known from 6 million year-old fossils from Florida (Shaw and Cox 2006)
Three species of Smilodon existed between 2.5 million and 13,000 years ago
S. gracilis: smallest and earliest. Found mainly in eastern North America
S. populator: largest, about the size of modern lions. Found in South America
S. fatalis: intermediate in size. Found in North America and Pacific coastal areas of South America
Smilodon fatalis became extinct about 13,000 years ago.
PREHISTORIC DISTRIBUTION & HABITAT * *How Do We Know This? Scientists use knowledge of the earth's rocks, global plate
and the chemical process of fossilization
to make sense of fossil
distribution patterns and ancient habitats.
Smilodon fossils found in North America, Central America, and South America.
Andes mountains separated populations of Smilodon gracilis from S. populator
Over 1,200 specimens of Smilodon fatalis from Rancho La Brea asphalt deposits, Los Angeles, California
Large collection of Smilodon fossils also discovered at Talara tar seeps in Peru (Anderson 1984)
Most fossils found in sediments from plains or woodland environments
In contrast to another saber toothed cat, Homotherium, Smilodon not found in cave deposits
Smilodon's anatomy suggests its preferred habitat: (Shaw 2001)(Cox and Shaw 2006)
A robust skeleton, with exceptionally powerful limbs indicates an ambush predator
Ambush predators depend on forest habitats, brushy plains, margins of woodlands
PHYSICAL CHARACTERISTICS* *How Do We Know This? Careful study of fossil bone or tooth anatomy yields
much exact information
about placement and strength of muscles, tendons,
ligaments, nerves, and blood vessels.
In rare cases, skin and hair impressions or
actual skin or hair is preserved.
Body weight is more difficult to gauge because fat
leaves no impression on the skeleton.
(Christiansen 2007) (Christiansen & Harris 2005) (Jefferson 2001)
(Shaw & Cox 2006) (Turner 1997) (Van Valkenburgh & Sacco 2002)
Estimated Body Weight: Smilodon fatalis: 160-280 kg (353-617 lb) Smilodon gracilis: 55-100 kg (121-221 lb) Smilodon populator: Up to 400 kg (882 lb) Body Length:Smilodon fatalis: 175 cm (68.9 in) (measured rump to snout) Height at Shoulder:Smilodon fatalis: 100 cm (39.37 in) Tail Length:Smilodon fatalis: 35 cm (13.8 in)
Similar in size to modern African Lion, but more robust with slightly shorter limbs.
Nearly 18 cm long (7 inch) canine teeth (Homotherium's canines were around 10 cm or 4 in long.
Canine teeth blade-like, curved slightly back towards throat
Flattened and curved rather than more rounded like modern cats
Serrated on both edges
Incisor (front) teeth are conical & set in curved row (rather than flatter, in a straight row as in modern cats)
As in all cats, no molar teeth for chewing
Jaw gape is enormous - approaching 130 degrees (compared to around 65 degrees for modern large cats)
Gape necessary for food items to get past the long canine teeth
Canines of saber toothed cats more resistant to bending and breaking than round canines (Christiansen 2007)
Bite force strong enough to put strain on skull where jaw muscles attached
Computer models suggest bite only one-third as powerful as that of modern lions
Bite may not have been used to hold prey immobile; prey restrained with paws prior to inflicting the killing bite (McHenry 2007)
Teeth may be used to roughly gauge age as shown in a study of a population from Rancho La Brea (Meachen-Samuels & Binder 2009)
Dentin fills in pulp cavity as animal ages
Young middle and old age assessments possible
If approximate age is known, when this info combined with measures of jaw length, possible to separate a group of fossils into male vs female (otherwise large old females and males, for example, can be confused with younger, smaller males - size alone can't be used)
Not known; camouflage coloring (spots, stripes, marbling) might have helped this robust predator stalk prey. (Jefferson 2001)
Very little or none; few differences between sexes in teeth, skull, and skeleton. (Van Valkenburgh & Sacco 2002)
Other Physical Characteristics
Strong retractable claws
Front and back limbs about the same length
Short tail, unlike modern large cats
Not much "chin" on lower jaw to brace the long upper canine teeth
Other saber tooth cats like Homotherium have "chin"
Flexible hyoid bone supporting the tongue similar to modern lion's may have allowed Smilodon to roar
Brain of Smilodon had furrows like all modern cats, indicating similar hearing, eyesight and limb coordination
Brain anatomy revealed in natural and lab-made casts that fill the brain cavity of a fossil skull
BEHAVIOR & ECOLOGY* *How Do We Know This? Since direct observation of a fossil animal's behavior
isn't possible, paleontologists use
comparison and contrast with living animals for
guidance. Tracks can sometimes
reveal further clues.
(Carbone et al 2008) (McCall et al 2003) (Meachen-Samuels and Binder 2009) (Shaw & Cox 2006) (Shaw 2001)
Evidence for sociality somewhat contradictory
Smilodon was social and had cooperative hunting
Because they often were injured and managed to heal, presumably other members of the group shared food with them (Shaw 2001)
Because like modern social carnivores, they were attracted in great numbers to the distress of trapped prey at La Brea asphalt pools; presumed solitary species of carnivores were much less common at La Brea. (Carbone et al 2008)
Smilodon was not social; no cooperative hunting
Because Smilodon's brain was relatively small (social mammals with cooperative feeding have large brains) (McCall et all 2003)
Social behavior not necessary to survive while healing; cats can heal quickly without feeding, drawing on stored metabolic reserves (McCall et al 2003)
Sexual dimorphism not present
(Meachen-Samuels and Binder 2009)
Males not distinguishable from females based on size
Male aggression assumed to be less pronounced than in more dimorphic extinct American Lions (P. atrox)
Smilodon was a top predator in its ecosystem
Prey availability for Smilodon' was equal to or greater than in East Africa today (Van Valkenburgh & Hertel 1993)
As the Pleistocene ended Smilodon and other top carnivores often had broken teeth; possibly this indicates intense competition for food and feeding all the way to bone. (Van Valkenburgh & Hertel 1993)
Since Smilodon did not feed on bones (no bone-crushing teeth), it may have associated with scavenging, bone crushing hyaenas (Van Valkenburgh et al 1990)
DIET & FEEDING* *How Do We Know This? Clues to fossil mammals' diets come from not only teeth,
but also skull shape, from fossil dung and gut contents, from microscopic viewing of
wear on teeth, from lab analysis of oxygen isotopes
in bone and teeth, and by looking
at diets of similar modern animals.
(Annyonge 1996) (Feranec 2002)
(Valkenburgh et al 1990)
Size of Smilodon teeth and robustness of skeleton indicates prey would have included large mammals such as bison, giant ground sloths, possibly young mammoths and mastodonts, horses, camels
Oxygen isotopes preserved in tooth enamel show that S. gracilis in Florida ate browsing animals such as large pig-like Platygonus and large-headed llamas, Hemiauchenia.
Smilodon probably avoided eating bone
or contacting it with its teeth
Microscopic study of tooth wear finds few grooves and pits in teeth indicating a diet of flesh (Annyonge 1996) (Van Valkenburgh et al 1990)
Smilodon did not break its knife-like canines any more than it broke its other teeth
Probably didn't use canines to help restrain prey, in contrast to modern lions (Van Valkenburgh and Hertel 1993)
DISEASES AND PATHOLOGY*
*How do We Know This? Abnormalities in fossils bones may show evidence
of arthritis, cancer, nutritional stress, fractures and more.
(Bjorkengren et al 1987)(Duckler 1997)
Fused vertebrae from arthritis (Duckler 19997)
Ossification between vertebrae
with several possible causes
- seen in La Brea specimens (Bjorkengren et al 1987)
Trauma and resulting infection
Inflammatory disease (ankylosing spondylitis)
Bone damage from impact of teeth of other sabertooth cats (Bjorkengren et al 1987)
Occasionally fractured teeth found imbedded in bone of victim
Broken legs, dislocated hips, bone infections, back injuries (Merriman and Stock 1932)
Thirty percent of 1,000 skulls
examined show erosion of the parietal bone where largest jaw muscles attached (Duckler 1997)
Long-term mechanical stress could cause microfractures, weakened bone, and bone thinning
Other carnivores show fewer and shallower depression than did Smilodon bones
Important Web Resources (and where to view fossils in museums):
Natural History Museum of Los Angeles County's George C. Page Museum has a web site introducing many of the region's Late Pleistocene animals, including Smilodon. The Page Museum at Rancho la Brea displays most of the iconic large mammal fossils and a large number of rarely seen bird fossils from Late Pleistocene times. Visitors can view technicians working in a large fossil preparation lab.
San Diego Natural History Museum's Fossil Mysteries: Has a description of Smilodon and a new reconstruction of a fleshed-out Smilodon by paleo artist William Stout. The museum's displays include many Late Pleistocene fossils plus original oil murals of the flora and fauna in southern California about 20,000 years ago.
The Paleobiology Database: This site is a scientific organization run by paleontological researchers from around the world. It features taxonomic and distribution information for the entire fossil record.