Tuesday, July 25, 2006

Giant Possum Skull


That's a very large fur-farm red fox skull to the right -- the largest I could find, and plucked from a bin of about 50 based solely on size. The skull at the left is that of an enormous possum found in the field this weekend. Note the cranial ridge of bone at the top of the possum's skull -- a simple indicator for the species.



We found a number of bones in the woods yesterday. The first set were two odd-looking things, which I recognized pretty quickly, and Mike B. did too, as the backbone and breast bone of a wild turkey.

Lots of deer bones around of course. And a groundhog skull. The winner, however was this enormous possum skull. Wow! This old boy was HUGE -- far and away larger than any possum I have ever seen alive.

How did I know this was a possum? The quick give away was the very large cranial ridge. Possums have such small brains that the brain case does not offer enough room to attach the muscles of the jaw. The evolutionary solution has been to create a prominent ridge of bone along the top of the skull in order to increase the surface area for the possum-jaw's muscle adhesion.

The prominent canids and the small side teeth are also features of a possum, which has has more teeth (42) than any other fur bearer in this hemisphere. The possum, of course, is a mammalian marsupial -- the only marsupial in this hemisphere.

Research indicates that "playing possum" is not really an act. Instead, a possum suffers a kind of nervous collapse when it is overstimulated. The result is a kind of temporary catatonia which, ironically enough, often keeps the possum alive.

The reason "playing possum" works is that the attack response in many dogs and other predators is genetic -- it has nothing to do with being "angry" or being "hungry". The reason a fox will kill as many chickens as it can when it gets in a chicken coop is that the jerky and fluttering movement of the chicken triggers a "mass murder" response within the fox. If chickens simply "played dead," like a possum often will, a vixen would pluck off one hen and be on her way.



Top row, left to right: normal groundhog, normal possum, large boar raccoon.
Bottom row, left to right, large red dog fox, enormous possum skull, American badger skull.

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