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.
(Jefferson 2001)(Kurtén & Anderson 1980) (McDonald 1981)
(Prusak et al 2004)
Describer (Date): C. H. Smith 1827 for Bison R. Harlan 1825 for Bison latifrons Fauna Americana: (Philadelphia: A. Finley). p. 273
J. Leidy 1852 for Bison antiquus Proc., Acad. of Nat. Sci. of Philadelphia, Vol. 6, p. 117
"Latifrons" comes from Latin words referring to a wide forehead
"Antiquus" comes from the Latin for "old' or "ancient".
First fossil bison described in North America was a Bison latifrons found in Kentucky (Peale 1803)
Bison taxonomy underwent a long period of taxonomic splitting that resulted in some 10 fossil species recognized in North America by Skinner and Kaisen in 1947.
This taxonomy in great need of revision (McDonald 1981)
Relationship of modern American bison and European bison is unclear at present, but both are quite similar genetically and can interbreed (Prusak et al 2004)
Wilson (1974, 1975) and Kurtén and Anderson (1980)
describe the Pleistocene fossil species Bison antiquus as a subspecies of the modern Bison bison., but later authors disagreed, preferring to classify
B. antiquus as a separate species from the modern bison (McDonald 1981) (Prusak et al 2004)
Modern North American bison have two recognized subspecies: the American Plains Bison (B. b. bison) and the American Wood Bison (B. b. athabascae). (McDonald 1981)
Even-toed hoofed mammals trace their ancestry back to at least 45 million years ago in Eocene times.
The Bison genus first appeared in southern Asia, around 2 million years ago (McDonald 1981)
Bison priscus was the ancestor of at least some of the North American bison
This species flourished in northern Eurasia and Alaska and may have been the dominant hoofed mammal there (Guthrie 1970)
Bison immigrated to North America several times in the Pleistocene during the low sea levels when exposed land connected North America and Asia
B. latifrons appeared by 500,000 years ago in North American and survived until around 20,000 years ago.
The first appearance of B. antiquus in North America was around 250,000 years ago (Jefferson 2001)
The B. antiquus line may have led to modern American Plains Bison whereas European bison may be descendants of Pleistocene bison that returned to Europe from North America.
B. antiquus and B. latifrons lived at the same time for part of their history (McDonald 1981)
B. latifrons became extinct around 20,000 years ago (McDonald 1981)
B. antiquus survived into the Holocene until around 5,000 to 4,000 years ago. (McDonald 1981)
Modern bison in America (Bison bison) and Europe (Bison bonasus) are genetically very closely related, yet researchers say they shouldn't be classified as simply subspecies. (Prusak 2004)
All bison nearly became extinct in North America at the end of the Pleistocene when much of the other megafauna did become extinct
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.
B. antiquus: North America, mainly in southwestern U.S., but also in Canada, Mexico and Central America. (McDonald 1981)
B. latifrons: United States, especially coastal California, Great Plains, Texas coastal plains, Florida. (Mcdonald 1981)
Few fossils from forested southeast and southwest
May have been present in Canada and Alaska, but glacial activity could have destroyed evidence.
B. antiquus fossils much more common than than B. latifrons.
may have inhabited heavily wooded and forested habitats (McDonald 1981)
Bison antiquus: probably inhabited open woodlands or savanna (McDonald 1981)
PHYSICAL CHARACTERISTICS* *How Do We Know This? Careful study of fossil bone or tooth anatomy yields much exact
about placement and strength of muscles, tendons, ligaments, nerves, and blood
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.
As in other bovid species, actual horns extended beyond the cores
BEHAVIOR & ECOLOGY* *How Do We Know This? Since direct observation of a fossil animal's behavior isn't possible,
comparison and contrast with living animals for guidance. Tracks can
reveal further clues.
(Geist 1999) (McDonald 1981)
Bison latifrons: Very large horns signaled fitness to potential mates as well as serving to ward off predators. (Geist 1996)
may have been more solitary than B. antiquus
Forest habitats/woodland habitats with limited resources wouldn't support large populations of large herbivores
Vocalizations would have been an important means for mate-finding in somewhat closed habitats.
May have had life-style similar to modern moose
B. antiquus had stronger herding and more complex social behavior than B. latifrons. (McDonald 1981)
B. latifrons may have engaged in dominance and fighting behavior characterized by hooking, not butting (McDonald 1981)
Larger horns have curvature that places tips above frontal bones of skull.
Foreheads are flattened rather than domed (domed-head modern bison are fortified against head-butting)
Bison antiquus fighting behavior probably characterized by more head to head impacts..
Bison latifrons probably used sheer size a deterrent for predators
No evidence for hunting by humans
Bison antiquus probably used flight as a predator defense
Bison antiquus shared the grassland environments
with horses, camels, giant ground sloths, and mammoths.
DIET & FEEDING* *How Do We Know This? Clues to fossil mammals' diets come from not only teeth, but also
skull shape, amount of
indicated by bones for a stomach and guts, from fossil dung and gut
contents, from lab analysis of oxygen isotopes
in bone and teeth, and by looking at diets of
similar modern animals.
Bison are ruminants
that graze and browse
Bison latifrons: more of a browser than a grazer
An eye-level browser, feeding on small trees and shrubs
Bison antiquus: more of a grazer; some browsing
Feeding on low-growing herbs and shrubs
REPRODUCTION & DEVELOPMENT * *How do We Know This? Isotope studies of elements present fossil bones and tusks in
about timing of reproductive stress, and timing of nursing.
Clues to stages of development come from tooth
replacement patterns and closure of sutures
in skull and limb bones.
(Duffield 1973)(Guthrie 1990) (Jefferson 1989)
Many juveniles of Bison antiquus are found at the La Brea asphalt deposits
Baby teeth and permanent teeth in the jaws (when compared with modern bison) indicate that these animals died 2-4 months after birth or at the same season in subsequent years.
Researchers concluded that bison were not permanent residents at the site, but were regular spring/summer visitors.
The actively growing ends of bones (epiphyses) fuse in the vertebrae during the 7th year for European bison. (Duffield 1973)
A study of 1322 Pleistocene bison jaws revealed that around age 14 to 16 years the first lower molar has been completely worn down (Guthrie 1990)
Death from debilitation begins around 10 years when at least half the molar's enamel is worn away.
A frozen 36,000 year-old Steppe Bison carcass (Bison priscus) in Alaska was estimated to be 8 or 9 years old, in his prime (Guthrie 1990)
Saber-toothed cats (Smilodon) and American Lions (Panthera atrox), and possibly Dire Wolves (Canis dirus) would have preyed on extinct bison.
A frozen Pleistocene Steppe Bison in Alaska had scratch marks on the legs and bite marks on the face consistent with an attack by more than one lion. (Guthrie 1990)
Many bison were killed by early human hunters.
One hunting method seen in Wyoming at the 10,400 year-old Twelve Mile Creek site involved driving 10 Bison antiquus over a cliff.
DISEASES AND PATHOLOGY*
*How do We Know This? Abnormalities in fossils bones may show
evidence of arthritis, cancer, nutritional stress, fractures and more.
(McDonald 1981) (Morrow 2006) (Fisher 2001) (Jefferson and Goldin 1989)
Valley Fever fungal infection (Coccidioides) recognized in Bison antiquus
Fungal organisms visible in stained thin sections of fossil bone from lower jaw
Lesions in bone similar to those in modern cattle infected with coccidioidomycosis
This pathogen isn't found in Nebraska today but is in arid parts of California, New Mexico, Arizona, Texas, and northern Mexico.
Researchers hypothesize Valley Fever fungus either once occupied a wider geographic area or, that bison migrated between Nebraska and areas to the south where the pathogen did live.
Many abnormalities observed in fossils of B. antiquus
Most abnormalities are in the skull and horns
Teeth also affected; exhibit malformation, overcrowding, poor orientation
Most abnormalities occur in fossils dated between 11,000 and 9,000 years ago
This pattern likely due to inbreeding in small isolated populations experiencing intense human hunting pressure
A 20,000 year-old fossil deposit at Natural Trap Cave in Wyoming had evidence of tuberculosis and other bone diseases (Rothschild & Martin 2003).
Many Bison antiquus bones had osteoarthritis caused by Mycobacterium tuberculosis (identified by DNA).
One bison had diffuse idiopathic skeletal hyperostosis (DISH) - abnormal bone growth in the skeleton from unknown causes.
Important Web Resources (including where to view fossils in museums):
FAUNMAP -- This useful website, created and maintained by the Illinois State Museum, gives the known distributions in map and list format for many fossil species in North America.
A Bison latifrons fossil specimen is exhibited at the Idaho State Museum in Pocatello, Idaho
The Paleobiology Database -- This site is run by paleontological researchers from around the world. It features taxonomic and distribution information for the entire fossil record.