Wednesday, March 3, 2010

Giant Pleistocene Beaver

Cryptozoology is the study of wacky, but allegedly real, creatures like bigfoot and the Loch Ness monster—a field generally not pursued by professional scientists. I must admit to having been fascinated by cryptozoology since I was a child, even though realistically speaking I estimate that 95% of it is bogus. (And, realistically speaking, there is also the problem of being considered insane for having such interests.) Part of the appeal is simply entertainment, willingly suspending my disbelief to imagine how cool it would be if sea serpents and the like were real. But there is also the intellectual opportunity to analyze cryptozoological claims as they relate to areas of science that I find interesting, such as paleontology, zoology, and ecology.

A few months ago, I came upon an article concerning John Warms, a man from Canada. He claims to have seen a giant Pleistocene beaver (Castoroides ohioensis), and the burrows of such a beaver, in his native Manitoba. Fossils of the eight-foot, two-hundred pound animal are well known in North America; the species is thought to have become extinct at the end of the last ice age, along with the other megafauna of the era, including mammoths, saber-toothed cats, and ground sloths.

The article profiled Warms as he traveled to Utah in search of other legendary animals. (That seems like a mistake—if you get a lead on a giant Pleistocene beaver, stick with him; don't go running off to Utah.)

His web site, illustrated with elementary school-level drawings of supposed Canadian monster animals, does not inspire confidence. However, a modern population of the giant Pleistocene beaver strikes me as being in that 5% of cryptozoological phenomena with some possibility of existence.

Are there giant Pleistocene beavers frolicking in the waters of Manitoba?

On the positive side, I have long thought that the Canadian boreal region, which is heavily forested and very sparsely populated, would be a good place for an unknown animal to live undetected. The giant beaver only disappeared from the fossil record about 10,000 years ago, which is the blink of an eye (or some other cliche) in geological terms. And a recent study of the isotopic composition of the giant beaver's teeth indicates that its diet was mostly aquatic plants, and not trees, which might diminish its impact on the landscape and allow it to more easily escape detection.

On the other hand, no one has ever acquired a modern specimen of the giant Pleistocene beaver; it's hard to accept that even in the wilds of Canada a giant beaver could escape not only science but also the fur trade. Millions of regular North American beavers (Castor canadensis) were trapped for their pelts, to the point that the species was eliminated over most of its range, but there is no record of giant beaver skins.

A potential complicating factor is Bergmann's rule, a trend in warm-blooded mammals that the size of individuals increases as one moves northward through the animal's range. What appear to the casual observer to be members of a distinct, giant species might be regular beavers at the high end of their natural size variation.

In any event, I much prefer a giant Pleistocene beaver to a giant Pleistocene Beiber.

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