A new Pliensbachian ichthyosaur from Dorset, England

The first ichthyosaur to be recorded from the Pliensbachian Stage of the En glish Lower Liassic is described as Leptonectes moorei sp. nov., extending the geological range of Leptonectes to the Pliensbachian. According to crit eria for assessing the maturity of ichthyosaurs, it is concluded that L. mo orei is an immature individual of a relatively small, slender and short sno uted species close to the earlier long-snouted L. tenuirostris (Conybeare) which ranges from the Rhaetian to the Sinemurian. The presence of a short-s nouted leptonectid in the Pliensbachian suggests two contrasting patterns o f rostral morphology within the clade Leptonectidae in the latest Early Jur assic, rostral reduction within the genus Leptonectes and rostral elongatio n in Excalibosaurus and Eurhinosaurus.