We need Tarzan to fill the gaps!
These guys, Nsungwepithecus and Rukwapithecus (it’s not that hard to pronounce, try it) are considered by Stevens and his team as the oldest crown Catarrhines – [Google translate palaeo-primatish to English: “as closely related as the ancestors of you and your cousin the proboscis monkey (we all knew there were some facial similarities!)”]. Technically speaking, these fossil discoveries pushed the origin of modern Catarrhines back from 20 to 25 million years ago, a date which is closer to molecular results (25-30 mya). Astonishing eh? Well it is for me but there’s another reason why I wanted to talk about this paper: gaps.
As many people might know, the fossil record contains some serious lacunas; thick layers of rock containing either very few or no fossils at all. One example mentioned in this paper is the scarcity of fossils from the Oligocene period; very few bones for palaeontologists to gnaw… The Oligocene was, however, a period of massive changes, in climate and all that stuff but also the time when placental mammals evolved from their primitive to modern forms. So the lack of fossils from this time is always frustrating when you want to understand macro-evolutionary patterns. But why have we found so few Oligocene fossils until now? Of the many explanations Stevens et al. suggest that “Possible reasons […] include limited deposits of appropriate age, particularly […] below the equator, complicated by densely vegetated topography in more tropical environments”. And that’s why I find this article so exciting! Traditionally, fossil primates were excavated in deserts or northern latitudes, which is typically where they are fairly rare nowadays! Therefore, I’m happy to see that there is a true effort being made to look for fossils in biodiversity hotspots such as Tarzan’s neighborhood (or the Tanzanian Rukwa Rift Valley in this paper) where these new primates were discovered.
I think one of the most important things to come from this paper is that it’s proof of a real effort to look for the fossils in the true biodiversity hotspots which, I’m sure will lead to far better comprehension of modern mammalian history. These new primates came from Africa but people are also working in Peruvian jungle and interesting new discoveries are not limited to just primates…
Photo credit: wikimedia commons