The teeth are large, and supported on expanded conical osseous eminences, which are anchylosed to the alveolar ridge of the jaw (acrodont). The crown of the tooth is conical and recurved, with the outer face nearly flat, and this space is bordered on each side by a longitudinal ridge; giving the tooth somewhat of a pyramidal figure. (See Ligns. [228-230].) Professor Owen states that the crown consists of a body of simple and firm dentine, with fine and close-set calcigerous tubes, enclosing a simple pulp-cavity; irregular processes of the latter extend as medullary canals into the conical base of the tooth, but not, as in the Iguanodon, into the substance of the coronal dentine; the dentine is invested with a moderately thick coat of enamel.[658]
[658] See Odontography, p. 258, and pl. lxxii.; the student should also consult Cyclop. Anat. Phys. Art. Teeth.
The vertebræ of the Mosasaur, as is usual in the existing lizards and crocodiles, are concave in front and convex behind, and the neural arch is united to the centrum by suture. The entire vertebral column of M. Hoffmanni appears to have consisted of 131 vertebræ, of which 97 belonged to the tail.[659] This Mosasaur was about twenty-five feet long.
[659] See Cuvier, Oss. Foss. vol. v. pp. 326-334.
Lign. 229. Tooth of Mosasaurus: magn. twice.
Either a pterygoid tooth of M. Hoffmanni, or a jaw-tooth of M. gracilis.
Chalk. Gravesend.
(In Mr. Wetherell’s Collection.)
This extinct lacertian reptile forms an intermediate link between the Saurians without pterygoid teeth (Monitors) and those with them (Iguanas). Its crocodilian affinities are but partial.
The Mosasaurus appears to have had webbed feet, adapted or crawling on land as well as for swimming,[660] and a long and vertically expanded tail, serving as a powerful oar, and enabling the animal to stem the roughest waters.