I am going to be very busy today so I won’t get an in depth post up on Australopithecus sediba until tomorrow. In the meantime three items jumped out at me so I thought I would, briefly, mention them.
The nearly vertical mandibular symphysis presents a weak lateral tubercle, resulting in a slight mental trigone, and a weak mandibular incurvation results in a slight mentum osseum.
In other words it has a chin! Something early Homo and Neandertals don’t have. This is very perplexing – but maybe I’m over-interpreting this sentence.
But there is no way to over-interpret this:
Thus, although the dentition and postcranial skeleton are at odds in the degree of apparent size differences, the overall level of dimorphism, if these sex attributions are correct, appears slight in the Malapa hominins and was probably similar to that evinced by modern humans.
If you have been following paleoanthropology for the last couple of years you may be able to spot the problem. KNM-ER 42700 is a female skull, attributed to Homo erectus, dating to 1.55 MYA. It is incredibly small and suggests that sexual dimorphism in H. erectus was much greater than previously thought. BSN49/P27 is a pelvis, also attributed to H. erectus, that dates to 0.9-1.4 MYA and stature estimates indicate that it, also, belonged to a small member of H. erectus. If Berger et al are correct then sexual dimorphism decreased up until Au. sediba increased until H. erectus then decreased and some later date – and note the above two specimens aren’t that much more recent than Au. sediba.
Then there are the teeth. Much has been made of the fact that the teeth are more or less similar in size to H. habilis and H. erectus but in the figures provided in the paper they are also similar in size to Au. afarensis. Which similarity is more important?
Update: Okay I’m home and have discovered something else that raises some red flags – or at least makes me say WTF? From Scientific American’s blog:
When asked during a press teleconference whether he had found any tools at the site, Berger said he had not commenced formal excavation of the site [bold mine – afarensis] and so did not want to talk about artifactual remains.
Filed under: Australopithecina, Australopithecus, Australopithecus afarensis, Australopithecus sediba, Hominini, Homo, Homo erectus, Homo habilis, Osteology, Paleoanthropology | Tagged: Australopithecus afarensis, Australopithecus sediba, Homo erectus, Homo habilis |