Later that evening, Rachel and my other student intern, Chuck, were able to work on this jigsaw puzzle and we were all pleasantly surprised to see that all of the fragments went together and formed the back of the right side of a phytosaur skull. Even better is that the bone in the upper left corner, the squamosal, is complete and thus we could identify the specimen as a "leptosuchine" phytosaur.
For those of you not familiar with these animals the photo below is a complete skull from a different locality which was found by one of my interns (Joanna) last summer.
The new partial skull is significant because it represents the best phytosaur specimen known from the locality in which it was found. Furthermore, phytosaurs have biostratigraphic significance so this is another data point for the Chinle Formation in the park (more on this at the SVP meeting in Bristol this year).
Finally, this specimen demonstrates the importance of thoroughly investigating all fragments no matter however insignificant they may seem at the time. This was a pile of badly busted up, hematite-encrusted chunks of bone, which actually represents a common condition for fossils found in the Chinle Formation, especially in sandstone units. A lot of patience on the part of Rachel and Chuck and a bit of glue revealed that this scattered mess was actually a scientifically important specimen. Likewise the complete skull found by Joanna last season was only represented on the surface by a small (golf ball circumference) patch of minute bone fragments in the bank of a small wash. Joanna astutely noticed these and carefully followed the fragments into the bank revealing the entire skull!
Also see David Hone's recent post on what a significant find may look like when you first find it.