Thursday, January 12, 2006

Human ancestors hunted by Eagles?

Tuang Child, Australopithecus africanus

A replica of the Tuang child find, image taken from Skulls unlimited

One of the very early Australopithecus africanus finds is the so-called Tuang child, which was discovered in a limestone cavern along with the bones of many other mammals including baboons and antelope. Because of the heap of bones, it was hypothesized that the Tuang child was the victim of a predator and ended up in the heap with all the other prey. The early money was on a leopard or hyena, but a theory which has been around for quite a while is that a predatory bird, such as the crowned hawk-eagle (which can prey on animals up to 30 kg; the Tuang child was probably about 20 kg) was the predator in question. The first argument in favor of a bird was based on the mix of prey present in the bone heap, with small animals predominating as might be expected for a bird that has to fly off.

A second line of argument (for example here ) favors predatory birds based on the pattern of bone damage to the Tuang skull. Leopards and their ilk do a lot of gnawing, but birds are limited to what they can slice open with their beaks (which is still an awful lot- they brain a lot of their prey via the palate, leaving the postcranial skull alone). The authors of this theory propose looking at the long bones of the various mammalsin the Tuang assemblage, because birds will slice the ends off to get at the marrow while hyenas can just crush them.

The news this week is now (also at afarensis ) is that the bones of the eye sockets of the Tuang child find have radial scratches of the sort that a bird's talons would leave. Birds will strike a treeborne monkey and puncture the skull, and then wait for the animal to die before hauling it off. Sounds like a shark's method.

I just finished reading the Hobbit to the boys. Wouldn't want to have been one of those goblins.

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