The youngest occurrence of ichthyosaur embryos in the UK: A new specimen from the Early Jurassic (Toarcian) of Yorkshire

Abstract

The remains of between six and eight ichthyosaur embryos, still situated within a fragment of the rib-cage of the parent animal, are described. Each is represented by a string of vertebral centra, some with associated ribs. Other skeletal elements, including possible skull material, are represented only by isolated bones, none identifiable with certainty. The small limestone boulder in which the ichthyosaur specimens are preserved was collected from the beach at Sandsend, near Whitby, North Yorkshire, and derives from the Whitby Mudstone Formation (Hildoceras bifrons Ammonite Biozone) of the Toarcian Stage of the Lower Jurassic. The specimen cannot be identified beyond Ichthyosauria indet. However, it represents the geologically-youngest occurrence of ichthyosaur embryos thus far recorded from the UK and the first such occurrence to be reported from Yorkshire.