Big Papers

The September 9 issue of Science is dominated by the discovery of Australopithecus sediba.Here is the link to the main paper on the subject (http://www.sciencemag.org/content/333/6048/1421.short). The specimens pre-date the first occurrences of Homo (our genus) in the fossil record. According to the authors, this means that A. sediba is a potential candidate as the direct ancestor to Homo. The authors use careful wording saying that A. sediba "cannot be precluded as an ancestor to Homo," which is true. At least they recognize how difficult it is to identify direct ancestors in the fossil record (in fact, I think you would need some OUTSTANDING evidence to make that argument). Either way, the specimens seem interesting and there are several other papers in the same issue on A. sediba.

The fall issue of Paleobiology also contains an interesting paper on the evolution of diet and tooth wear in fossil whales (http://www.bioone.org/doi/abs/10.1666/10038.1). The authors investigated wear facet patterns and stable isotopes in several artiodactyl (even-toed hoofed mammals) groups and sister groups to modern whales. They found that whale tooth wear was much different from their closest relatives (the artiodactyls) and conclude that fossil whales changed their diet before the evolution of morphological changes to the jaw and tooth crowns.  This is an interesting result that should keep us palaeoecologists on our toes!

Finally, the September 2 issue of Science contains an interesting paper on a new woolly rhino (http://www.sciencemag.org/content/333/6047/1285.short). The age of the fossil assemblage and the morphology of the rhino suggest that the woolly variety evolved in Tibet prior to the onset of the Pleistocene ice age. The authors conclude that the "woolliness" was a pre-adaptation that enabled the megaherbivores to survive the cold Pleistocene. I don't like the term pre-adaptation because it seems to suggest that the rhinos were psychic and grew hair because they knew the ice age was coming. Of course, this is not what they mean but I would prefer the use of different terminology (and throwing out the term pre-adaptation altogether in fact).  What they really mean is that faunas adapted to the cold Himalayan environment probably gave rise to the woolly animals of the Pleistocene.