PaleoAngola field season 2011 – Blog entry 5

A great week full of mosasaurs

The past week of fieldwork at a handful of localities in the south of the country has been very succesful indeed. Among many other things, we recovered a couple of interesting fossils that may tell us more about the evolution and distribution of a peculiar group of mosasaurs, the globidensines. These ‘Globidensini’, as they’re officially called, were a rather diverse group of mosasaurs, ranging in size from less than three to more than ten meters.

During our fieldwork at Bentiaba in the south of Angola, in the past couple of years we focused a lot of effort at the Bentiaba site on the layers which were deposited a few million years before the end of the Cretaceous. This yielded so far a very well-preserved, and by now also well-documented mosasaur fauna, including a new, small globidensine, which we named Prognathodon kianda.

This year we moved ‘up’ in time at Bentiaba, to the slightly higher (and therefore, in this case, younger) layers, exposed a bit further east. The mosasaur fossils from these higher levels show an interesting similarity with the fauna we know from Maastricht (where team member Anne Schulp is based), and the discoveries this week included remains of a larger Mosasaurus hoffmanni-like mosasaur, as well as a single tooth of a small, and rather elusive globidensine mosasaur, Carinodens. A single tooth may not sound like much, but considering how rare fossils of this particular animals are, it certainly counts as a very important discovery. The discovery of a few fragments of an interestingly different Halisaurus-like mosasaur is another highlight. We also finally got around recovering the remains of what appears to have been a much larger globidensine mosasaur – not a complete skeleton yet, but the fragments we have point at a body size of more than ten meters at least.