food supplies that are abundant (i.e. squids), but considering that plesiosaurs and ichthyosaurs were also abundant and that the plesiosaurs' swimming speed is likely very slow compared to squids, this interpretation may be unlikely unless Liopleurodon was an ambush predator. Another possiblity is that Liopleurodon may have been an opportunistic feeder, with cephalopod hooklets being representative of the acid resistant residue of its varied diet—skeletal components of various vertebrates that lost to the acid environment of the gut; however, since the thin sections through the gut don't reveal the presence of otoliths (calcium carbonate structure of vertebrates located in the vestibular labyrinth) which are known to occur in the gut of cetaceans, fish may not have been an important part of its diet. The other possibility is that the pliosaur fed on large cephalopod-feeders, with the hooklets representing the residues of the stomach contents of the pliosaur's prey, but there is no firm evidence to this claim. It is also notable that this specimen preserved at least 7 gastroliths, which probably weren't used for grinding based on the well-preserved conditions of the hooklets. It is possible either that the pliosaur accidentally swallowed the stones and they remained in its gut, or that the stones represent the "acid resistant residue from carbonate cemented sandstone." See also List of plesiosaur genera Timeline of plesiosaur research Notes References External links Liopleurodon information and photos, The Plesiosaur Directory Article on the giant pliosaur skull once assigned to Liopleurodon, Tetrapod Zoology Pliosaurids Middle Jurassic plesiosaurs of Europe Late Jurassic plesiosaurs of Europe Fossil taxa described in 1873 Taxa named by Henri Émile Sauvage Oxford Clay Sauropterygian genera