A thyreophoran dinosaur from the Early Bajocian (Middle Jurassic) of the Isle of Skye, Scotland

Abstract

Synopsis The proximal parts of the right ulna and radius of a thyreophoran dinosaur from Bearreraig Bay, Isle of Skye, represent the first occurrence of this type of dinosaur from the Middle Jurassic rocks of Scotland. The incompleteness of the bones and the lack of more diagnostic features does not allow a precise identification although the ulna has more features in common with that of a eurypodan (stegosaurs and ankylosaurs) than a basal thyreophoran. The earliest identifiable stegosaur from Europe that has similar proximal expansion of the ulna is the middle Callovian (Middle Jurassic) Lexovisaurus of England and France. The ulna of the ankylosaur Mymoorapelta from the Upper Jurassic of Western Colorado, also shows close morphological similarity to the Scottish bone. Other ankylosaur fragments have been recorded from as early as the late Bajocian (Middle Jurassic) of England. The stratigraphic horizon from which the new bones come from is the Bearreraig Sandstone Formation (Early Bajocian, Middle Jurassic).