The American Bison – Played a Role in the Extinction of North American Mega Fauna

The large areas of grassland and forest that covered much of the United States and other parts of North America were populated by a diverse range of large mammals.  Elephants, Mammoths, Camels, the American Lion, Dire Wolves and Horses roamed the great plains.  Large animals in an eco-system are called mega fauna.  The extinction of many of these large creatures is put down to a number of causes, over hunting by Clovis man, disease and dramatic climate change.  However, at least one distinguished American palaeontologist reckons that the American Bison may have had a role to play in the demise of many of the species of North American large mammal.

The American Bison (Bison bison) is the largest land mammal in North America today, with adult bulls weighing as much as 1 tonne and standing 2 metres tall at the shoulder.  They are regarded as a “keystone” animal, their herding, grazing and wallowing behaviours shape the landscape and the environment around them.  It is this influence on the environment that, it is claimed by at least one American palaeontologist, can help explain the demise of other large species 10,000 years ago.

Eric Scott, curator of palaeontology at San Bernardino County Museum in Redlands, California has commented on the North American mega fauna extinction and indicates that the Bison could well have played a role in the demise of other large herbivores.  The reduction in large mammalian plant-eaters would have had a significant impact on the large predators in the area, perhaps speeding up the extinction of the Sabre-Tooths, a number of types of large bear and the American Lion.

There was even a type of Cheetah living on the plains (Miracinonyx), not a true Cheetah but a genera of cats related to the Puma that evolved long, lean bodies and specialised in fast pursuit of prey animals.  Indeed, scientists have speculated that the American Pronghorn Antelope, was probably these fast felines preferred prey.  This antelope is capable of running at over 55 mph, but now with the fast running cats extinct, there is nothing on the American continent quick enough to run one down.

For Eric Scott, extremely knowledgeable on Californian prehistoric mammals from the Pleistocene, the migration of the American Bison from Asia across the Bering Straits into North America may be one of the reasons for the mega fauna extinction.

He sees the introduction of this large bovine as “a change in the composition of the animal community”.

The aggressive behaviour of large herds of Bison would have affected the ecosystem, perhaps to such an extent that it speeded up the demise of a number of other species of large mammals.

“When they (sic Bison) graze, when they trample, when they wallow they change biological communities”;  observed the palaeontologist, other animals have to adjust their behaviour to accommodate the Bison, if they don’t they may face extinction.

The role of the Bison in the extinction event at the end of the Pleistocene, was one of the areas covered by Eric, in a series of winter lectures being given by museum staff.  Horses and Camels did not return to the Americas naturally, for example the horse was re-introduced by the Spanish in the 16th Century.  Much can be learnt from the past, Eric Scott went on to comment on the changing climate of our times and drew parallels with the Pleistocene/Quaternary extinction events.

The greenhouse-gas-induced climate change is a major concern, he commented:

“The 1980s were the hottest decade on record.  They were eclipsed by the 1990s as the hottest decade on record.  In 2008, I can tell you that the 1990s are being eclipsed by this decade as the hottest decade on record”.

The eminent palaeontologist went on to add:

“So many animals that went extinct have living representatives which are also endangered or threatened.  What we learn about the ice age extinctions does have a very real potential to tell us about what’s going on in the world today.  But we need to be asking the right questions”.

With the United States the source of more greenhouse gas emissions than any other country, much more than every country in the European Union combined, such lectures by Eric Scott and other scientists, may play a role in helping the U.S. government to recognise the serious predicament the planet is facing.

 

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