clidastes

from The Century Dictionary.

• noun A remarkable genus of extinct reptiles, of the order Pythonomorpha, from the Cretaceous deposits of North America, having each ramus of the lower jaw provided with a peculiar articulation behind the middle of its length and between the splenial and angular bones, whence the name. About a dozen species have been described, varying in length from 12 to 40 feet. Also Cleidastes.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Paleon.) A genus of extinct marine reptiles, allied to the Mosasaurus. See Illust. in Appendix.