surface parallel one another and cranial midline to posterior base of diverging suspensorial rami, forming narrow rectangular field medially on parietal. Squamosal sends abbreviated wing medially to contact ramus irom parietal. Otosphenoidal crest on prootic covers exit for cranial nerve VII laterally. Fourteen to sixteen teeth in pterygoid. Suprastapedial process of quadrate moderately large; tympanic ala very thick. Stapcdial pit elliptical in form. Sixteen-18 teeth in dentary. Small projection of dentary aritcrior to first dentary tooth. Medial wing Irom angular contacts or nearly contacts coronoid. Dorsal. edge of surangular very thin Iamina of bone rising anteriorly to position high on posterior surface of coronoid. Retroarticular process of articular triangular in outline with heavy dorsal crest. Mandibular teeth usually compressed, bicarinatc and with smooth enamel surfaces." Russell noted that his diagnosis was exclusively based on C. propython and C. liodontus and might not necessarily apply to C. sternbergii (later referred to its own genus, Eonatator) or C. iguanavus. Teeth and tooth replacement Mosasaur teeth are of rather uniform morphology (with a few exceptions, such as in Globidens) with a pointed and curved tooth crown that sits on a pedicel composed of bone. The enamel surface is smooth and the crown is subdivided into a lingual and labial surface while the outer surface of the crown is made of enamel and the inner layer is made of dentine. Fossil specimens show evidence of upright vertically positioned developing replacement teeth. Snakes have been thought of as the only squamates with replacement teeth that develop in a horizontal posteriorly inclined position. Snakes deviate from the usual varanoid pattern of tooth replacement, in that their replacement teeth develop in a horizontal inclined position and rotate, however snakes differ from Mosasaurs because they do not possess the resorption pits found in Mosasaurs. Mosasaurs, including Clidastes, and snakes both share the traits of thecodont tooth implantation, and a recumbent position of replacement teeth. However mosasaurs develop replacement teeth by rotating within the resorption pits that are at the base of functional teeth. This is different from snakes because snakes have recumbent replacement teeth that lay horizontal and rotate into functional position when needed. In mosasaurs like Clidastes, once the functional tooth is lost, a new tooth pedicel develops for the replacement tooth. In the case of mosasaurs though, they differ from the thecodont dentition pattern of archosaur and mammals because mosasaurs show true ankylosis and not a