Now, one of the themes of my dissertation is that there is lots of interesting information to be gleaned from fossils that we've known about for a long time (many of the A. robustus mandibles featured in my research have been known for decades). But dammit if some of these much more recently discovered fossils point to tantalizing variation in hominids just later than 2 million years ago (note I'm careful to say "variation" rather than "diversity"). In light if this variation, Adam discusses the similarities between one of these Kenyan fossils (KNM-ER 60000) and the large mandible from Dmanisi, which was discovered in only in the year 2000 (Gabunia et al., 2002).
Piggy-backing off Adam, I'd like to point out similarities between another of the new fossils, the KNM-ER 62000 face of a juvenile, and the recently discovered A. sediba juvenile face (Berger et al., 2010). These two fossils are at the same stage of dental development, so they're roughly at the same stage of life. They are close in geological age, but A. sediba is from South Africa. Below are figures of A. sediba (left) and the ER 62000 face (right). The pics should be to scale, modified from the original publications. (sorry I couldn't remove the background from the top left one)
Leakey et al. liken these new Kenyan fossils to the cranium KNM-ER 1470, from the same region and at 1.9 million years old. But what's weird to me is that ER 1470 actually looks a bit more like the juvenile A. sediba in the side view (as reconstucted; the face and braincase of ER 1470 are actually separated, leaving it unclear just how the two parts fit together). Here are all three specimens, to scale:
|From left to right: ER 62000, A. sediba, ER 1470|
The point of all these comparisons is not to say whether these fossils are the same species, but rather to point out that there are actually striking similarities between fragmentary fossils, and it's not clear what exactly these similarities (or differences, for that matter) mean. Maybe my eye was drawn to the ER 62000-A. sediba comparison not because of any evolutionary relationship, but because these fossils are in similar stages of growth and development - if it weren't waaaaay past my bedtime I'd love to compare these fossils with other similarly-aged fossils (like D2700 from Dmanisi and KNM-WT 15000, also from Kenya).
All of these fossils (except ER 1470) were discovered in the past few years. I've said it before and I'll repeat it now: this is a great time to study paleoanthropology.
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Berger L, de Ruiter DJ, Churchill SE, Schmid P, Carlson KJ, Dirks PHGM, and Kibii JM. 2010. Australopithecus sediba: A New Species of Homo-like Australopith from South Africa. Science 328: 195 - 204.
L. Gabounia, M.-A. de Lumley, A. Vekua, D. Lordkipanidze, and H. Lumley. 2002. Découverte d'un nouvel hominidé à Dmanissi (Transcaucasie, Géorgie). Comptes Rendus Palevol 1(4):243-253
Meave G. Leakey, Fred Spoor, M. Christopher Dean, Craig S. Feibel, Susan C. Antón, Christopher Kiarie, & Louise N. Leakey (2012). New fossils from Koobi Fora in northern Kenya confirm taxonomic diversity in early Homo Nature, 408, 201-204 DOI: 10.1038/nature11322