Article: Leptopterygius tenuirostris and other long-snouted ichthyosaurs from the English Lower Lias

One of the commonest ichthyosaurs from the English Lower Lias is the long-snouted species Leptopterygius tenuirostris, known principally from Street, Somerset. Because of the vagaries of preservation there are few complete skeletons, and the problem is exacerbated by the occurrence of composite specimens. The authenticity of a quarter of the specimens studied here is in doubt, and hence caution is needed when working on material from Somerset. The occurrence of a tail bend in L. tenuirostris is confirmed by the presence of wedge-shaped centra in the caudal region of several skeletons. The vertebral column was probably not steeply downturned, and may have been essentially straight in life.Eurhinosaurus, unusual for its abbreviated mandible, may be closely related to L. tenuirostris and is therefore of interest here. The suggestion that it occurs in the Upper Lias of England is confirmed. The contention that Eurhinosaurus lacked a tail bend is questioned because a wedge-shaped centrum has been identified in one specimen.Two trivial names besides tenuirostris have been used for long-snouted ichthyosaurs: latifrons and longirostris. The former is a taxon dubium, while the latter should be used only in combination with Eurhinosaurus.