Thursday, March 4, 2010


As I thought about how to frame this post, several biblical metaphors pooped [sic, he said] into my head: "Drowned in the (Missoula) flood," and "Not one of the deadly sins." The one that appealed to me most was "Biblical proportions," until I realized that "Biblical!" by itself would make a fine interjection (I needed to do a little footwork to come up with that word; I couldn't remember the grammatical term) like "awesome!" or "rad!"

So here's the story: about 1970, a pile of bones were discovered and identified as a mastodon. They have recently been re-identified as a giant ground sloth.
According to Yvonne Addington of the Tualatin Historical Society, bones from the 1970s previously identified as a mastodon – a hairy, elephant-like thing – have now been identified by Portland State University scientists and National Park Service experts as a gigantic, 3 to 4 ton, 20-foot-long sloth – a hairy, bear-looking thing with big claws.
I have definitely heard of giant ground sloths before, and while I don't have my copy of Geology of Oregon at hand, I'm pretty sure I had known they were part of Willamette Valley's Pleistocene megafauna. What hadn't really registered with me was the shear size of these behemoths: we're talking about the size of an elephant, and standing bipedally, as pictured, twice as tall! Not only that, I just looked at the wiki entry for Megatherium (I can't tell if the Tualitin specimen is in that genus or not), and it says
Some recent morpho-functional analysis indicates that M. americanum was adapted for strong vertical biting. The teeth are hypsodont and bilophodont, and the sagittal section of each loph is triangular with a sharp edge. This suggests the teeth were used for cutting, rather than grinding, and that hard fibrous food was not the primary dietary component.

There is a common misbelief that the sabre-toothed cat Smilodon hunted Megatherium, but healthy adult sloths were far too large for Smilodon to attack. Richard Fariña and Ernesto Blanco of the Universidad de la República in Montevideo have analysed a fossil skeleton of M. americanum and discovered that its olecranon - the part of the elbow to which the triceps muscle attaches - was very short. This adaptation is found in carnivores and optimises speed rather than strength. The researchers say this would have enabled M. americanum to use its claws like daggers.[3] The conclusion is that due to its nutrient-poor habitats, Megatherium may have taken over the kills of Smilodon. A number of adult Glyptodon fossils exist in which the creatures died on their backs. This hints at Megatherium scavenging or hunting this animal, as no other known animal existed in South America during that period that could flip an adult Glyptodon.
(Insert: I just did the tracking around to figure out where this fits into the nomenclatural frame, and it's a different family, not just a different genus. Harlan's ground sloth is a Myolodontid... not that that means too much to me.) So we may be talking about a 20-foot tall predator, built for speed. Suddenly, the Pleistocene Willamette Valley sounds like a much more hostile place than I would have imagined a few minutes ago.
But man, oh man, so Biblical!

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