Posts Tagged ‘Bison bison’

A Pleistocene Species of Bison (Bison antiquus) Survived in Canada until 4830 Calender Years Ago

June 5, 2015

The terminal radiocarbon dates for North America’s Pleistocene megafauna consistently translate to about 12,000 calendar years BP.  Because these dates are so consistent for so many different species, scientists assume Pleistocene megafauna became extinct 12,000 years ago.  I hypothesize this date reflects when these species became rare and local in distribution and not when these species actually became extinct.  The chance that bones will become preserved in the environment for thousands of years is low and depends on unlikely circumstances.  For example a flood has to rapidly cover remains of an animal with sediment before scavengers consume the carcass, and the soil chemistry has to have anti-bacterial qualities that prevent microbial consumption.  Then, a man has to be lucky enough to even find it.  An animal had to have been abundant in its environment to appear in the fossil record. I believe most species of Pleistocene megafauna continued to exist more recently than 12,000 years ago, but most more recent populations happened to live in areas where the process of bone preservation was uncommon.

There is evidence supporting my hypothesis.  The discovery that mammoths lived on the Pribiloff Islands until 5000 years ago is well known.  Some suppose the geographical isolation of the island temporarily sheltered the mammoths from the continental extinction event (caused by anthropogenic activity or environmental change) of 12,000 years ago.  But DNA evidence in Alaskan permafrost shows that mammoths and horses survived on the North American continent as recently as 9000 years ago.  Though there are no known fossil remains this young, the sedaDNA in frozen soil is evidence mammoths and horses were shedding hair, shitting, and pissing in Alaska several thousand years past the commonly accepted extinction date.  A less well known specimen, the Kenora bison, also supports my hypothesis.

Kenora is located in Ontario

Kenora is in the western part of Ontario.  This region supported a relic population of Bison antiquus as late as 4830 BP.

 

 

bison outline.jpg

Size comparison between modern day bison on the left and Bison antiquus on the right.  DNA evidence suggests modern bison evolved from Bison antiquus, but apparently, there was a relic, geographically isolated population of the Pleistocene bison in Canada as recently as 4830 years ago.

Jerry McDonald identified the Kenora bison as Bison antiquus, an extinct species formerly known from just the Pleistocene.  Carbon dating of the bones yielded a calendar year date of 4830 BP.  The bones of the specimen were found by a man excavating a peat bog near Kenora, Ontario, Canada.  This specimen apparently died of old age in a pond and was later covered by 14 feet of sediment.  It survived a broken jaw and suffered from malnutrition.  This individual was not getting enough calcium in his diet, but neither the broken jaw nor deficient diet caused his demise.  The Kenora bison lived in an environment interpreted as a pine/oak woodland.  (I studied the pollen graph included in Dr. McDonald’s paper and determined the trees in order of abundance were pine, birch, alder, oak, and spruce.)   Lily pads covered the pond the bison died in.  Perhaps, he was enjoying a last meal of lily pads before he collapsed.  This specimen is the northeasternmost known occurrence of this species.

Bison antiquus evolved from Bison latifrons, an even larger, longer-horned species, about 24,000 years ago.  Bison antiquus averaged 30% larger than modern bison (Bison bison) and had significantly larger horns and longer limbs.   However modern bison have bigger thighs and are better runners.  Scientists believe human hunters shaped the evolution of Bison antiquus to Bison bison.  During the Pleistocene big cats preyed upon Bison antiquus.  In response to this environmental pressure Bison antiquus were large and powerful, enabling them to fight off lions and saber-tooths when in prime condition.  But humans presented a different challenge.  In response to human hunting pressure smaller bison that reached sexual maturity at a younger age were more likely to survive and reproduce.  Smaller, more rapidly reproducing bison replaced the larger more powerful bison.  This is an excellent example of natural selection.  Human hunting pressure also selected for bison that tended to migrate long distances.  Bison antiquus already had migratory tendencies, but the presence of human hunters intensified this habit.  Bison that traveled for many miles away from humans were more likely to survive.

DNA evidence supports the assumption that modern bison evolved from Bison antiquus beginning about 12,000 years ago.  Bison antiquus was genetically much more diverse than modern bison.  Every clade became extinct, except for the 1 that led to modern bison.  This clade was well adapted to survive in an environment with human hunters and soon spread throughout western North America.  Some scientists regard the species of bison that lived from 12,000 BP-5,000 BP to be an intermediate form between Bison antiquus and Bison bison.  It’s known as Bison occidentalis.

The Kenora bison must have been from a relic population of Bison antiquus, geographically isolated from the clade that evolved into Bison bison.  Perhaps the 2 populations were separated by dense forest, unsuitable for bison.  This population of Bison antiquus lived in a region with a low density of human hunters.  Some time after 4830 BP, this population became extinct.  They were either overhunted by man or became genetically swamped by interbreeding with Bison bison as the newer species expanded its range east.

Incidentally, I believe megafauna in southeastern North America were probably the first to be wiped out by humans.  This region has the best climate and year round food resources in North America, and therefore supported the earliest population of Indians dense enough to impact megafauna populations.

References:

McDonald, Jerry; and George Lammers

“Bison antiquus from Kenora, Ontario, and notes on Evolution of North American Bison”

Tributes to the Career of Clayton Ray: Smithsonian Series Publication 2002

Wilson, Michael; Leonard Hills, Beth Shapiro

“Late Pleistocene Northwest Dispersing Bison antiquus from the Bighill Formation, Gallelli Gravel Pit, Alberta, Canada, and the fate of Bison occidentalis”

Canadian Journal of Earth Science 45 2008

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

June 11, 2010

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.