Abstract

Continuing preparation of the unique specimen of Baryonyx walkeri has already provided much additional information on this recently described dinosaur, including the startling observation that the lower teeth are twice as numerous per unit length of jaw as are the upper teeth. The characters of the animal demonstrate conclusively that it is a theropod dinosaur, that it is not a spinosaurid, that it cannot be fitted satisfactorily into Gauthier's recent classification of the theropods, and that it is sufficiently distinctive from all other theropods to justify the present authors' earlier proposal of a new family Baryonychidae. Some fragmentary material described from the Late Cretaceous of Niger and Morocco and referred to the Spinosauridae is more likely to be baryonychid.

Introduction

Our lecture at the Drumheller Symposium on a new theropod dinosaur from the Wealden of Surrey was followed by our publication (Charig and Milner 1986) of a preliminary account of the animal, in which we named it Baryonyx walkeri. A few of the more important pieces were illustrated. Since then, the continuing preparation of the skeleton has revealed the existence of further elements (in particular both quadrates, the articulating region of the right mandible, an isolated dorsal neural spine, and the left radius and ulna). It has also extended our knowledge of some of the elements described previously. Conversely, we are no longer sure about the presence of any material belonging to the pubes.