Marine Reptiles From the Upper Lias (Lower Toarcian, Lower Jurassic) of the Yorkshire Coast

SUMMARY Fossil marine reptiles have been collected in some abundance from several sites along the Yorkshire coast over the last 225 years. Much of this material has remained unstudied and there is confusion over the provenance of most specimens. A detailed study of early collectors’ reports has revealed the sources of some specimens, and others have been dated by means of associated ammonites and matrix. A complete list of all specimens known to us is given, and these include 55 crocodiles, 69 ichthyosaurs, 33 plesiosaurs and one pterosaur. Reptiles are rare in the Lower and Middle Lias of Yorkshire. The richest horizons are within the Upper Lias (Lower Toarcian, Whitbian), with 14 specimens from the Jet Rock Formation and 144 from the Alum Shales Formation (predominantly the Main Alum Shales). The best localities have been the Whitby – Saltwick section (137 specimens) and the old alum quarries at Kettleness (5 specimens) and Loftus (4 specimens). The faunas from these sites are unrivalled in the Upper Lias of Britain, and they show significant differences from the Upper Lias faunas of SW Germany (e.g. Holzmaden) and France.