Ken Angielczyk, an assistant curator at the Field Museum of Natural History, is searching for fossils of ancient mammal relatives in northeastern Brazil.  Today we worked in the Teresina area for the first time this year. We decided we would return to the quarry outside the town of Timon, where we found a very interesting fish skull last year. We’re just starting to prepare that specimen, so I can’t offer many details about it at this point, but it certainly seems to have a lot of potential. Based on that specimen, our expectations were high, and the quarry did not disappoint.  Not long after arriving today, Martha Richter literally stumbled across a partial skeleton of a terrestrial vertebrate, or tetrapod, preserved in a few pieces of rock in one of the quarry spoil piles. The main layer of the quarry that is used for paving material is the hard red siltstone that forms much of the vertical walls. However, at the base of the wall and exposed in some other areas, there is a softer sandstone that is too friable to use for paving, which is why pieces of it are mostly discarded.  It’s not an exaggeration to say that this specimen is the most exciting that we’ve found in our two years of fieldwork in the Parnaíba Basin. It appears to represent a type of amphibian and has a fairly short, broad skull that lacks the very elongated snout of the Prionosuchus. Therefore it is definitely something new to the basin. The size and shape are a bit reminiscent of the little jaw fragment that Domingas found a few days ago, so it might represent that animal. More preparation of both specimens will be necessary to say definitively whether that’s the case.  Beyond that, there was a lot of discussion of which group of amphibians the specimen might be part of, based on our attempts to interpret the anatomy exposed in the specimen. A couple of our guesses focused on two groups, the microsaurs and the amphibamids. Both are known exclusively from areas in the Northern Hemisphere during the Permian period, so finding one south of the paleo-equator would be an important discovery. Again, more preparation of the specimen will be necessary to be sure, and we’re all already thinking about what might be the best ways to approach this process. Every specimen is a unique problem when it comes to preparation, and the way this one is preserved suggests it will require a particularly delicate touch.  Luckily, the excitement of finding the skeleton was enough to keep us motivated for the rest of the day. It was very hot today, even by local standards, and the only other fossils we found in the quarry during the rest of our searching were small, unidentifiable fragments of bone. The plan for tomorrow is to do more prospecting for fossils in a couple of other quarries in the area. Our discovery today has given us an idea of what rock layer will be good to target, and it would be great if we can find more material like this.
Excited by the discovery of a tetrapod skeleton at a quarry in Teresina, Brazil, paleontologists ponder its classification among amphibians.