Thursday, September 21, 2006

Young Australopithecus skull and partial skeleton found

This has been all over the news. I thought I'd just mention the fact that this juvenile had a large hyoid bone, and that according to the shape of the scapula, humerus, tibia and femur, the legs are very different from chimps and gorillas, but the arms are still "ape-like". The authors discuss that the arm structure can be interpreted as just a lagging phylogenetic remnant or as evidence of the importance of arborealism in their "locomotor repertoire".

This skeleton was actually found five or six years ago, if I remember correctly. I also found it interesting that they cited the Nature paper about endurance running in Homo (not in a particulary interesting context, however).

A juvenile early hominin skeleton from Dikika, Ethiopia

Zeresenay Alemseged, Fred Spoor, William H. Kimbel, René Bobe, Denis Geraads, Denné Reed and Jonathan G. Wynn

Nature 443, 296-301(21 September 2006)

Abstract: Understanding changes in ontogenetic development is central to the study of human evolution. With the exception of Neanderthals, the growth patterns of fossil hominins have not been studied comprehensively because the fossil record currently lacks specimens that document both cranial and postcranial development at young ontogenetic stages. Here we describe a well-preserved 3.3-million-year-old juvenile partial skeleton of Australopithecus afarensis discovered in the Dikika research area of Ethiopia. The skull of the approximately three-year-old presumed female shows that most features diagnostic of the species are evident even at this early stage of development. The find includes many previously unknown skeletal elements from the Pliocene hominin record, including a hyoid bone that has a typical African ape morphology. The foot and other evidence from the lower limb provide clear evidence for bipedal locomotion, but the gorilla-like scapula and long and curved manual phalanges raise new questions about the importance of arboreal behaviour in the A. afarensis locomotor repertoire.

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