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BROWN, D. S., CRUICKSHANK, A. R. I. 1995. The skull of the Callovian plesiosaur Cryptoclidus eurymerus, and the sauropterygian cheek. Palaeontology, 37, 4, 941–953.
David S. Brown and Arthur R. I. Cruickshank Mechanical preparation of a relatively complete new skull specimen of Cryptodidus eurymerus has revealed the palate and cheek regions for the first time, permitting a more accurate reconstruction to be given. The wider phylogenetic implications of differing cheek and orbit configurations in sauropterygians are discussed and a cladogram given: the Cryptoclididae and the remaining plesiosauroids are sister groups; deep ventral cheek excavation arose through loss of the diapsid lower temporal arch and is a shared derived character of cryptoclidids, whereas an enlarged orbit and narrow vertical jugal bar are apomorphies. The palatal and mandibular structure of Cryptodidus is derived in comparison with pliosauroids: coronoids, prearticulars, suborbital fenestrae and the large pterygoid flange are all absent. These differences relate to feeding habit: Cryptodidus fed on small soft-bodied prey, and shows no adaptations for resisting torsional forces upon the jaws. Underwater olfaction similar to the pliosauroid system may have been present in Cryptodidus. The Palaeontological Association (Free Access)