Todd Wood's Take on Danuvius

Todd Wood is always interesting to read, even if I don't share his chronological leanings.  He has thoughts on the new Miocene ape from Bavaria, Danuvius:

Based on the fragmentary remains, we make some really interesting observations about the anatomy of Danuvius. These apes had strongly opposed big toes, which would allow them to effectively grip things with their feet. Their tibiae (shinbones) have the kinds of joints that would allow them to walk upright, and their femora (thighbones) support that conclusion. These apes might have been in some way bipedal. The arm bones they found have traits that are associated with suspensory locomotion, like hanging from tree branches. The body size was fairly small, about the mass of a bonobo.

As I mentioned in my post, I think the evidence for bipedalism is vastly over-stated and, even if it can be shown that this “Extended Limb Clambering” is shared by other fossil ape finds from the region, there is no particular reason to think that these critters were ancestral to later hominins. It is entirely likely that they exhibited a separate adaptation to this particular style of locomotion.  Todd raises some other questions, though, that are not answered in the paper:

So why not address similarities of Danuvius to later fossil hominins? The authors are trying to establish a new means of locomotion that they call Extended Limb Clambering (ELC). So they compare Danuvius to living primates (where the authors know how they get around), and they're interested in comparing it to contemporary Miocene apes of Europe. But they're not all that excited about other comparisons to later fossil forms like Ardipithecus, Australopithecus, or Orrorin. They also don't relate their findings to later fossil apes in Europe like Graecopithecus or the Trachilos tracks, both of which have been linked to hominins or bipedality. Perhaps they don't think those things are worth talking about (maybe because they're skeptical of Graecopithecus like I am), but I guess I just don't agree.

I think that part of the reason that these questions are not raised is because there is so much of a gap between these finds, chronologically and geographically. There is simply with which to relate them. As Todd points out, the hominin status of Graecopithecus is dubious, at best, and, even if the Trachilos tracks are hominin, they are still quite a distance from Bavaria and six million years later in time.

For now, this fossil ape stands on its own.  If we find other evidence of incipient bipedality in other forms in the area and can relate them to later forms, then the picture might change.  For now, though, Danuvius is a very interesting, odd Miocene ape. 

Was the LCA in Europe????

Was the last common ancestor of apes and humans in Europe?  That seems to be the gist of a study published in the PLoS One.  Nicole Mortillaro, of CBC News reports:

A jawbone discovered by German troops in Athens during the Second World War could be evidence that apes and humans diverged 200,000 years earlier than the current theory says.

Chimpanzees and bonobos are the nearest known relatives to humans, sharing 99 per cent of our DNA. It's believed that we split between five and seven million years ago.

However, researchers analyzing two fossils — a jawbone from a German museum and an upper premolar from a collection in Bulgaria — concluded their ages to be roughly 7.2 million years, and belonging to a pre-human.

From the paper in PLoS:

The split of our own clade from the Panini is undocumented in the fossil record. To fill this gap we investigated the dentognathic morphology of Graecopithecus freybergi from Pyrgos Vassilissis (Greece) and cf. Graecopithecus sp. from Azmaka (Bulgaria), using new μCT and 3D reconstructions of the two known specimens. Pyrgos Vassilissis and Azmaka are currently dated to the early Messinian at 7.175 Ma and 7.24 Ma. Mainly based on its external preservation and the previously vague dating, Graecopithecus is often referred to as nomen dubium. The examination of its previously unknown dental root and pulp canal morphology confirms the taxonomic distinction from the significantly older northern Greek hominine Ouranopithecus. Furthermore, it shows features that point to a possible phylogenetic affinity with hominins. G. freybergi uniquely shares p4 partial root fusion and a possible canine root reduction with this tribe and therefore, provides intriguing evidence of what could be the oldest known hominin.

Hominin, in this case, means humans and their premodern forms.  I think it is more than somewhat suspect to base a far-reaching hypothesis on one trait, even if it is the p⁴ root. It is commonly held that the last common ancestor of apes and humans was in Africa, sometime around 7.5 to 8 million years ago, but we have no fossil evidence to support that position.  While it is certainly true that the further back in time you go, the more ape-like our ancestors get, there is simply no smoking gun.

The world will not end if the LCA is, in fact, in southern Europe, but if it is, then it raises some interesting questions.  For one, if the LCA is in Europe, why are all of its hominin descendants in Africa?  So far, even discounting Sahelanthropus, which is a surface find and was crushed, all of the late Miocene and early Pliocene hominin remains are found in either the Afar triangle (Ardipithecus) or the Tugen Hills, in Kenya (Orrorin tugenensis).  If you add Sahelanthropus, then Chad comes into the picture. Additionally, why have we found no post-split hominids in southern Europe?  So far, all that has come out of the ground in this region is middle to late Miocene apes.

Other hurdles exist to acceptance of this idea.  For one, it is pretty clear that our closest living relatives, genetically, are the chimpanzees, who reside in the tropics of central Africa.   Next on the list is the gorilla, also found in the tropics of Africa.  Why have we found no precursors to these hominoids in southern Europe? 

On the other hand, the fossil find has been securely dated to the Messinian Event, in which the Mediterranean Sea effectively dried up, suggesting the possibility that the ancestors of the Pliocene hominins from North Africa migrated from southern Greece.  If this is so, then it raises the dark and ominous thought that much of the information regarding the LCA lies at the bottom of the Mediterranean Sea. That is terrible to contemplate.  This would also mean that Chimpanzees and Gorillas are the survivors of a group of Miocene apes that ranged from southern Europe to central Africa.  We know that the ancestors of chimpanzees once upon a time occupied the East African Rift Valley, but are now restricted to central and west Africa.   If their original range extended up into Egypt and beyond, then perhaps we are looking at a similar situation for their ancestors, as well.  

A whole lot more investigation needs to be done and more fossil remains need to be found to shore up the European LCA hypothesis.  Given that this new information does not come from newly discovered fossils does not raise my hopes.