Were there Three Species of Bovid Roaming Southeastern North America during the Late Pleistocene?

After a thorough review of the evidence in the scientific literature I’ve come to the conclusion that three species of bovid–all of them now extinct–lived in what’s now Georgia until the great megafauna extinction, circa 12,000 calender years ago.

The long-horned bison (Bison latifrons) was long thought to be ancestral to a species of bison known as Bison antiquus that had horns intermediate in size between those of Bison latifrons and the modern species (Bison bison).  Bison antiquus probably did evolve from Bison latifrons, but apparently there was enough differentiation in habitat preference between the two, so that long-horned bison continued to exist even after a segment of that population had evolved into Bison antiquus and spread all across the continent.  On the rest of the continent Bison antiquus  may have completely replaced Bison latifrons, but in the southeast both survived, and perhaps occasionally shared the same range and hybridized.

This is a photo I took at the Georgia College and State Museum located in Milledgeville of a long-horned bison skull originally discovered at Clarks Quarry, Glynn County, Georgia.  The carbon date on this specimen approximately equals 14,000 calender years old, a time period which is 8,000 years later than when Bison antiquus supposedly replaced Bison latifrons.  Yet, specimens of Bison antiquus have been reported from Florida and South Carolina that date to about this same time, so the shorter-horned variety simultaneously inhabited the southeast as well.

The species are so similar that scientist have difficulty telling the difference between the two based on fossil material, unless the skull with at least part of the horn is found intact.  Teeth alone, the most commonly found fossil material, can’t be used because there’s virtually no difference between the two species.  Bones posterior to the skull do differ–Bison latifrons bones tend to be larger–but the range in size overlaps too much for certain species identification.  Horn size is the only definite way of telling the difference between the species.

A third bovid species, the woodland muskoxen (Ovibos cavifrons), ranged over most of North America.  Its fossils are more commonly found north of the Mason-Dixon line, but specimens of this species have been excavated in Lousiana, Mississippi, Tennessee, and Virginia; suggesting the southern limits of its range probably extended into the Georgia piedmont.  The woodland musk-oxen was taller, thinner, and probably not as thick of fur as its living relative–the woolly musk-oxen.  It’s also known as the helmeted musk-oxen because its horns were shaped like a helmet.

All three were likely aggessive and dangerous animals–a real hazard for predators to attack.  The two Pleistocene bison species defended themselves from dire wolves, saber-tooths, and the giant panther/lion (Panthera leo atrox),  much like African water buffalo battle lions and hyenas in today’s Africa.  Woodland musk-oxen likely formed impenetrable defensive perimeters similar to those of their living relatives.

What could have been the reason these species co-existed here in what’s now Georgia?  According to one fleeting reference, the long-horned bison may have been a beast of open woodlands, while Bison antiquus  was a denizen of open plains.  Woodland musk-oxen preferred high dry meadows.  Though their ranges overlapped in places, the three species did have a preference for different individual habitats.  I think long-horned bison thrived on the warm coastal plain savannahs of Georgia where herds of Bison antiquus (or as I prefer to call them– northern bison) occasionally intruded, but the latter preferred cooler prairie-like regions to the north.    Cool dry prairie habitat spread due to fluctuations in climate related to the last glacial maximum, but the gulf stream created a warm thermal enclave, preferred by the long-horned bison, along the Atlantic coast.  The warm grasslands favored by long-horned bison remained, thus they were like a relic species.  Both northern bison and woodland musk-oxen were probably draught tolerant.  Long-horned bison may have been more dependent on water, limiting where they could live when the climate changed to cool and arid conditions across most of the rest of the continent.

Within historical times two species of bovine lived tothether in Europe and Asia.  The European bison or wisent (Bison bonasus) occurred along with the aurochs (Bos taurus), the extinct wild ancestor of our domestic cattle.  The former, though now restricted to deep forests, liked open grasslands; the latter preferred riverine woodlands and meadows.  The aurochs was more dependent on water, a trait of cows western cattlemen are well aware of.  They were less able to survive in dry habitats like bison can.  They were also less able to avoid human hunters because they couldn’t travel long distances away from water.  The ability to migrate long distances is what I theorize kept bison from completely becoming extinct until almost modern times when they came perilously close and would have become so, if not for human laws protecting them.  When bison migrated long distances, they were able to find areas sparsely inhabited by man, until the industrial age when such refuges became rare. 

It’s a shame Georgia’s remaining wilderness areas no longer have even one species of wild bovine.  Why?  Primitive people, like modern man, loved to eat steaks, roasts, and hamburgers (which paleo-Indians made by pounding tough pieces of meat with rocks).  The modern species of American bison (Bison bison) probably periodically colonized what’s now Georgia during the Holocene.  Indians extirpated these herds intermittently.  Europeans finally eliminated them from the state between 1760-1800 AD.

References: Mcdonald, J. N.

North American Bison: Their Classification and Evolution

University of California Press 1981

Note: My next blog entry won’t be until June 23rd.

Tags: Bison antiquus, Bison bison, Bison bonasus, Bison latifrons, Bos taurus, long-horned bison, Ovibos cavifrons, warm thermal enclave