A JUVENILE PLESIOSAUR (PLESIOSAURIA, REPTILIA) FROM THE LOWER LIAS (HETTANGIAN- LOWER JURASSIC) OF LYME REGIS, ENGLAND - A PLIOSAUROID-PLESIOSAUROID INTERMEDIATE

A partial skull and skeleton of a small, juvenile plesiosaur, part of the historically important Philpot Collection from Lyme Regis, England, is described. It is assigned tentatively to Eurycleidus arcuatus (Owen, 1840) and has a mosaic of features which make it difficult to place in a superfamily. The characters of the posterior elements of the skull and post-dentary bones are close to those expected in a plesiosauroid, whereas the anterior dentition and symphysis of the lower jaw are more typical of a phosauroid. The specimen is placed in the Pliosauroidea pending a phylogenetic revision of the Lower Jurassic Plesiosauria. From a reconstruction of the dentition and jaw-closing muscles, it is thought to have been a predator on soft-bodied or lightly armoured prey, such as belemnoids, ammonites or small fish.