Ichthyosaurs from the Jurassic of Skye, Scotland

Abstract

• Fossils of Mesozoic vertebrates are rare in Scotland, particularly specimens of marine reptiles such as plesiosaurs and ichthyosaurs. We describe a suite of ichthyosaur fossils from the Early to Middle Jurassic of Skye, which to our knowledge are the first ichthyosaurs from Scotland to be described and figured in detail. These fossils span approximately 30 million years, from the Sinemurian to the Bathonian, and indicate that ichthyosaurs were a major component of Scottish marine faunas during this time. The specimens include isolated teeth that could represent the most northerly known occurrences of the widespread Sinemurian species Ichthyosaurus communis, a characteristic component of the famous Lyme Regis faunas of England, suggesting that such faunas were also present in Scotland during the Early Jurassic. An associated humerus and vertebrae from Toarcian–Bajocian-aged deposits are named as a new genus and species of basal neoichthyosaurian, Dearcmhara shawcrossi. The taxonomic affinities of this taxon, which comes from a critical but poorly sampled interval in the fossil record, suggest that non-ophthalmosaurid neoichthyosaurians dominated European assemblages around the Early–Middle Jurassic boundary, and were later replaced by ophthalmosaurids, whose radiation likely took place outside Europe. Many of these specimens were collected by amateurs and donated to museum collections, a co-operative relationship essential to the preservation of Scotland’s fossil heritage.