ON A SMALL PREDATORY DINOSAUR FROM THE LATE CRETACEOUS OF EGYPT

The known tetrapod fauna of the Late Cretaceous Bahariya Formation (Cenomanian) of Egypt tends to be weighted towards very large taxa, such as the theropod dinosaurs Bahariasaurus, Carcharodontosaurus, and Spinosaurus, the sauropod dinosaurs Aegyptosaurus and Paralititan, and the crocodyliform Stomatosuchus. Small animals are largely absent from the assemblage. In early 2000, however, we recovered a number of shed theropod tooth crowns from Bahariya that have average crown base lengths (CBL) of 7.5mm and thus represent a rather small theropod. For comparison, Tyrannosaurus rex crowns generally average about 36mm in CBL. These teeth record the existence of another dinosaurian predator in a unit that already contains three moderately well supported species and some evidence of several others. They are also part of a small but growing body of evidence that many smaller tetrapods were members of the Bahariya fauna. Morphometric analyses of the Bahariya teeth intended to illustrate their position within the Theropoda show that they are superficially similar to dromaeosaurids. They fall within the variation range of CBL and crown height (CH) for Deinonychus and Dromaeosaurus, and are on average slightly larger than Saurornitholestes. However, the sizes of the serrations on the tooth keels (measured as densities of denticles per 5mm of keel length) are significantly smaller than in Deinonychus and Dromaeosaurus. Also, the denticle morphologies and the average crown base width (CBW) and CBL relationships are more reminiscent of abelisaurids than dromaeosaurids. A Bahariya abelisaurid would be significant in that the Abelisauridae is virtually absent from the Late Cretaceous of Africa. The Bahariya teeth appear to be distinct from a dromaeosaurid found in similar aged deposits in nearby Sudan. It thus appears that these new Bahariya teeth record the presence of a distinct small theropod in the Cenomanian of Egypt that is different from the known theropods of the Bahariya Formation as well as from the Sudanese dromaeosaurid.