Redescription of the dentition ofGrippia longirostris(Ichthyosauria) with a comparison withUtatsusaurus hataii

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Abstract
Reexamination of the dentition of Grippia longirostris (Ichthyosauria) provides new information, and also reveals errors in the original descriptions. A dental groove is present in G. longirostris, with shallow sockets at the bottom; hence, the implantation is subthecodont, at least in the posterior part of the mandible. There are two rows of maxillary teeth as originally described, but it seems that the lingual row comprises replacement teeth for the labial row, and that each replacement tooth is positioned distolingual of its predecessor. The anterior teeth are not well preserved in any of the specimens. The posterior teeth are blunt but rarely spherical, and are small both absolutely and relative to the skull width. The dentition and the jaw structure suggest a wide range of prey items, rather than strict durophagy as previously proposed. The dentition of G. longirostris is similar to that of Utatsusaurus hataii in general tooth structure, tooth implantation and replacement, and in relative tooth sizes, in contrast to previous interpretations.