Extinct Long-horned Bison & Ancient Bison (Bison latifrons and B. antiquus) Fact Sheet: Reproduction & Development

Isotope studies of elements present fossil bones and tusks in microscopic quantities give information 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.

•  Many juveniles of Bison antiquusare found at the La Brea asphalt deposits (Jefferson 1989)
• 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.

Duffield (1973)
Guthrie (1990)
Jefferson (1989)