Who, or What, Killed the Australopithicine?

Excavators were working on Member 1, at Swartkrans, when the victim was found. Member 1 dates to about 1.8 MYA and has yielded about 98 specimens of Australopithecus robustus.
Added Later: Ms. Ples is not A. robustus so I am removing that part of the post. Here is a picture of A. robustus

Our victim, labeled SK 54, was a juvenile. C. K. Brain, in The Hunters or the Hunted? An Introduction to African Cave Taphonomy describes SK 54 as follows:

SK 54, part of a juvenile calotte with two depressed fractures near lambda…Age estimate, immature.

For those of you not up on your cranial landmarks, lambda is defined as the point of intersection of the sagittal and lambdoidal sutures in the median sagittal plane. Here is a picture of lambda:
Here is a picture of SK 54 (I apologize for the smallness, it was the only picture I could find):
Note the two puncture marks. The question is, who or what made these marks? One suspicion would be fellow hominins, that was Raymond Darts’ guess. Marks like the above lead Dart to propose an Osteodontokeratic industry. Darts’ idea was popularized by Ardrey in his killer ape theory. There is, however, a better suspect – or suspects. You see the Member 1 fauna included a large number of carnivore remains, including leopards and false and true sabertooths ( i. e. Dinofelis and Megantereon). Later in the book, Brain has a photo of a leopard skull with canines placed near the punctures on SK 54 – it’s a perfect fit. An interesting picture, which leads to a larger question. In addition to containing a high number of hominins (about 87), Member 1 also contained a large number of baboons and bovines. Additionally, the carnivores made up about 11 % of total. Another interesting fact is that there is a correlation between live weight of the primates and the number of juveniles in the sample – in other words the bigger the primate the more juveniles in the sample. So it seems that rather than going after full grown primates our killer, or killers, were going after younger, smaller, prey items. Estimates indicate primates between 30-100 lbs were significantly represented in the sample. On the other hand, with antelopes species weighing over 200 lbs were significantly represented in the sample. Which leads one to believe that at least two different predators (with different prey size preferences) were involved.
There are two possible explanations. First, perhaps one of the large cats mentioned earlier was a specialized predator on primates? Second, perhaps the primates and hominins were using the area around Swartkrans as a sleeping site and the big cats were opportunistically preying on them (this is known to occur with modern baboons).
The point to be taken away from all this is how a simple question about trauma leads to wider questions. We started with trauma, looked at prey size preferences among predators and sleeping arrangements among primates. Interestingly enough, Brain didn’t just look at SK 54 but considering the entire faunal assemblage…think about it.

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8 Responses

  1. Interesting post. Is it possible that, rather than there being two different predictors with differing prey size preferences, the larger antelopes didn’t put up as big a fight (or climb a tree) as the full-grown primates? Perhaps that could account for the distribution of prey sizes.

  2. In this case, no. There are fossils of all three cats at Swartkrans. Dinofelis and Megantereon are both larger cats than Panthera pardus so it is not surprising that there are two different size classes with carnivore damage. Additionally, there seems to be a minor element of the assemblage that has been attributed to hyenas…

  3. Who, or What, Killed the Australopithicine?

    It was Colonel Mustard, with a pipe wrench, in the library.

  4. Juvenile primates are not as well tended as infants, or as watchful as adults. Back then there was a serious penalty for being inattentive.

  5. Maybe they had us for lunch, but we got the bastards back! :)

  6. Sts 5 is A. africanus.

  7. and while I’m at it… I don’t think any S. African robusts have been found at Sterkfontein. Only Swartkraans and Kromdrai.

  8. On STS 5 you are correct. I do not know how I could have made that mistake (my paleo teacher would be so disappointed). I really need to do a better job proofreading (I also noticed some typos which I will have to fix). The rest of the post, as I mention in the text, concerns Swartkrans.

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