Thursday, July 14, 2005

Quaker History/Natural Science/Harlan, Richard

Ground Sloths May Have Roamed Prehistoric Berkeley By JOE EATON ...

Berkeley Daily Planet/Berkeley/CA/USA/12-Jul-05

... You think of fossil-hunting as something that takes place in faraway barren places: the Flaming Cliffs of the Gobi Desert, the windy wastes of Patagonia, the Dakota badlands. But not downtown Berkeley. That was the source of Specimen 78858 in the UC Museum of Palaeontology’s collection, though, a fossil I finally got to meet at last year’s Cal Day. It’s a massive thighbone, the femur of an extinct ground sloth that inhabited these parts in the Pleistocene Era, tens of thousands of years ago, and it turned up when the Berkeley BART station was being excavated.

The species, depending on which sloth scholar you ask, is either Glossotherium harlani or Paramylodon harlani. Charles Darwin dug a Glossotherium, along with other former South Americans, out of the Bahia Blanca fossil beds in Argentina when the Beagle anchored there in 1832. The name, meaning “tongue-animal” (and I’ll get to that later), was coined by the anatomist Richard Owen, who later broke bitterly with Darwin after The Origin of Species was published. Harlani honors another nineteenth-century naturalist, Richard Harlan, who described the species from a jawbone found at Big Bone Lick, Kentucky. (Yes, a real place—a friend visited it during a business trip to Cincinnati. It’s a salt lick where sloths, mammoths, and other prehistoric megafauna left their skeletons.) Harlan’s more notorious younger brother Josiah, a rogue Quaker turned adventurer in feudal Afghanistan, appears to have been the real-life inspiration for Kipling’s “The Man Who Would be King.”

But back to Harlan’s ground sloth: These ungainly creatures evolved in South America when it was an island, with a fauna of sabertoothed marsupials, giant flightless predatory birds, and odd hoofed mammals. Ground sloths show up in the fossil record long before the modern tree sloths, the only survivors of a diverse lineage: three-toed sloths like the one Dr. Maturin brought aboard HMS Surprise and Captain Aubrey won over with cake soaked in grog, and two-toed sloths. Some palaeontologists believe the two-toed and three-toed sloths evolved from distantly related ground-sloth ancestors, acquiring their tree-hanging lifestyles and specialized anatomies through convergence. Another South American sloth, the sea sloth Thalassocnus, became adapted to an aquatic life.


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