The skull of the Callovian plesiosaur Cryptoclidus eurymerus, and the sauropterygian cheek
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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.
Palaeontology - Volume 37 Part 4 Pages 941-953Palaeontology - Volume 37 Part 4 Pages 941-953
Citations
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.