02 May 2011

Fossil Vertebrate of the Month: Archaeotherium

It's springtime, which means its time for class field trips, which to a paleontologist in Oregon can only mean it's time to head to the John Day Basin.  The fossil beds of the John Day country are some of the best continuous exposures of Oligo-Miocene sediments in the world, and have yielded everything from tiny "worm-lizards" to gomphotheres.  One of my favorite animals from the area, though, is the entelodont Archaeotherium from the Late Oligocene Turtle Cove Member of the John Day Formation (in the picture at left, Archaeotherium can be seen in the foreground, while the background is Sheep Rock, the most spectacular of the Turtle Cove outcrops).  Entelodonts have been popularly termed 'terminator pigs' or 'hell pigs,' and with good reason.  Opinions are split on whether or not entelodonts were particularly closely related to pigs (they may have been closer relatives of hippos), but they certainly would have been hellish things to encounter.  Their large, flat teeth are similar to those of bears, pigs, and humans (though on a much larger scale than the latter two), and like all these animals they were almost certainly omnivorous, making them some of the only artiodactyls to include meat as a major part of their diet.  The skulls of entelodonts, including Archaeotherium, are generally long and characterized by strange protuberances at the back of the jaw that may have served as anchors for muscles or, perhaps more likely, may have played a role in display or competition for mates.  Archaeotherium was a mid-sized entelodont, but members of the family could grow to huge sizes: the giant Daeodon (once known by the fantastic name Dinohyus, or 'Terrible Pig') grew to the size of a rhinoceros.

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