A revision of the Latipinnate ichthyosaurs of the Lower Jurassic of England (Reptilia, Ichthyosauria)

Abstract

A study of 60 latipinnate ichthyosaurs from the English Lower Lias (Lower Jurassic) reveals only four valid species; Ichthyo- saurus communis Conybeare, /. breviceps Owen, /. conybeari Lydekker, and /. tenuirostris Conybeare. Emended diagnoses and descriptions are given. /. communis, a medium-sized ichthyosaur reaching a maximum length of about 2.5 m, is the commonest species. /. tenuirostris, of similar size to /. com- munis, is less common and characterized by extreme snout length. /. breviceps, a small species with a maximum recorded body length of 1.3 m, is scarce and is characterized by an ab- breviated snout. The rarest latipinnate is /. conybeari, with only two individuals known. Both are small, with an estimated body length of 1.3 m in the larger individual. The snout is long, slender, and sharply pointed, and the orbit appears to be relatively large.