The New York Times, Science News and a multitude of other publications all have stories out on a just released paper from Nature on a new fossil foot specimen from Ethiopia. From the Nature News writeup on the paper:
The fossil, a partial foot, was found in 3.4-million-year-old rocks at Woranso-Mille in the Afar region of Ethiopia. Bones of the hominin Australopithecus afarensis — the species to which the famous ‘Lucy’ skeleton belongs — have also been found in this location and from the same period.
But unlike Au. afarensis, the latest find has an opposable big toe — rather like a thumb on the foot — that would have allowed the species to grasp branches while climbing. Modern apes have similar toes, but the youngest hominin previously known to have them is Ardipithecus ramidus, which lived about 4.4 million years ago. The details of the discovery are published today in Nature1.
I am not prepared to say exactly what the significance of this finding will be or whether or not the authors’ interpretation of the remains is correct. I do feel confident saying that all these finds are literally quite small, just a few foot and toe bones, they are likely to be quite important for a number of reasons. Much of the current uncertainty and argument about the pre-Australopithecine, possible hominin lineages (i.e. Ardipithecus, Orrorin, Sahelanthropus) stem from questions about locomotion and the evolutionary relationship between these lineages and Australopithecus. Given the fossil elements preserved here and the age of the finds (~3.57 Ma) these new discoveries from Ethiopia are in a position to address, if not resolve, questions on both topics.
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1. Haile-Selassie, Y., B. Z. Saylor, et al. (2012). “A new hominin foot from Ethiopia shows multiple Pliocene bipedal adaptations.” Nature 483(7391): 565-569.
