Family Mosasauridae. Teeth conical, pointed.
Upper Cretaceous. Mosasaurus Conybeare, Clidastes Cope, Platecarpus Cope, ? Sironectes Cope, Macrosaurus Owen, Brachysaurus Williston, Baptosaurus Marsh, North America. Plioplatecarpus Dollo, Prognathosaurus Dollo, Hainosaurus Dollo, Mosasaurus Conybeare, Europe (England, France, Belgium, Russia). Taniwhasaurus Hector, New Zealand.
Family Globidentidae. Teeth spheroidal, rugose. Imperfectly known.
Upper Cretaceous. Globidens, Gilmore, Europe and North America.
Fig. 184. Skeleton of Platecarpus as mounted in the Palaeontological Exhibit, Walker Geological Museum.
Tribe Amphisbaenia
Worm-like or snake-like, burrowing lizards, reaching a length of about one and one-half feet, either legless or with short tetradactyl front limbs immediately back of the skull. Body with numerous rings and without scales, the tail very short and blunt. Eyes minute. No postorbital or temporal arch, the quadrates fixed by the pterygoids; squamosals and tabulars indistinguishable; no postorbitals, lacrimals, or jugals; the nasals large. No parietal foramen. Brain-case in front partly enclosed by plates from frontals. Palate without openings back of the nares. Stapes short and stout. Vertebrae procoelous.
A curious group of burrowing lizards, moving by vertical rather than lateral undulations. The solid skull with the palate firmly fixed, the immovable quadrates, and entire absence of arches, together with the vestigial or absent limbs, are characters almost as far removed from the typical lacertilian structure as are those of the snakes,
