Saturday, June 09, 2012

SHORT-FACED BEAR SUB-FAMILY (Arctodus): Interconnectedness of Life

The Family of Bears (Ursidae) is usually divided into three Sub-families – Giant Panda (Ailuropodinae), True Bears (Ursinae), and Short-faced Bears (Tremarctinae).  Today only Spectacled Bear (Tremarctos ornatus) of South America represents the Short-faced Bear Sub-family.  Extinct members of the Tremarctinae included Arctodus pristinus (Lesser Short-Faced Bear), Arctodus simus (Giant Short-faced Bear), and Florida Cave Bear (Tremarctos floridanus).
            Although He had a similar lifestyle to European Cave Bear (Ursus spelaeus), Florida Cave Bear was not related to Her, since European Cave Bear was a True Bear.  Though large and muscular, He was a vegetarian who preferred to eat berries instead of meat.  As well as dwelling in caves, Florida Cave Bear also roamed the swamps and valleys of the Southeastern United States.
            Meanwhile Arctodus simus and Arctodus pristinus split off from an earlier Bear Ancestor – Plionarctos, who lived in North America about 10 million years ago.  A. simus evolved to be the largest carnivore on earth since the Age of the Dinosaurs.  Smaller than A. simus, A. pristinus was still larger than the other Carnivores.  Because their snouts were short in proportion to their heads, these Bears became known as the Short-faced Bears or Bull-dog Bears.  However, these ancient Bears had the same skull proportions as modern Bears.
            When the bones of A. simus were first discovered, her huge size led many paleontologists to believe that She was the ultimate carnivore. They reasoned that both A. simus and A. pristinus needed a lot of meat to survive, and therefore ate it in huge amounts.  However, upon further investigation, various scientists had to revise their ideas to include the theory that these Bears were probably specialized scavengers.
            When various paleontologists examined the leg bones of these two Short-faced Bears, they realized that these bones were too long for their large bodies if the Bears were to be active hunters.  Moreover, these Bears’ legs were not those of a carnivore, since these limbs could not withstand the quick turns and long periods of running after prey.  Thus, the physical makeup of the Bears’ legs points towards these animals being scavengers.
            Other signs that A. simus and A. pristinus were probably scavengers were the construction of their nasal cavities, jaws and teeth.  To be a scavenger, an animal needs a keen sense of smell to detect rotting corpses from long distances.  The large nasal cavities of these Bears provided Them with an acute sense of smell.  Meanwhile, the jaws and teeth of these Bears were designed to crack open bones to get to the nourishing marrow inside.
            Short-faced Bears went extinct when the mega-fauna (Mammoths and others) of the Americas and their predators died off.  Though They were impressive in their size and scope, Short-faced Bears were specialized scavengers.  With the loss of large carcasses, They had nothing to eat and could not sustain Themselves. 
            Short-faced Bears demonstrate the interconnectedness of life.  As scavengers, They ate the leftovers from the kills of the super-predators such as Saber-toothed Cats. When the large prey animals such as Mammoths died off, the predators and the specialized scavengers had little to eat. (Only generalists such as Grizzlies, who could live off on Insects and berries, would survive.)  In this ancient world of mega-fauna, life seemed abundant, but something happened to cause this particular thread of life to snap.  When that web of life broke, these large animals became doomed.   
When we recognize our interdependence with others in our lives, we can keep these webs strong.  Because we need many others in our lives, we must keep these threads alive.  For our own survival, we must preserve the diverse richness of life in our own environments.  When all of us act as one, the web of life becomes strengthened.

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