Tylosaurus dyspelor [art original] / [Charles R. Knight]

The top illustration, by Charles Knight, was reproduced in Henry Fairfield Osborn's article entitled: A complete mosasaur skeleton, osseous and cartilaginous, issued as Memoirs of the American Museum of Natural History, v. 1, pt. 4 (Oct. 1899), on page 186. The bottom illustration is a variation of the illustration on that same page and was based on drawings by W.D. Matthew and Bruce Horsfall under Osborn's direction. Published illustrations lack textual labels of the animal's parts. Illustration captions: Restoration of the great marine lizard (top); Restored skeleton of the great marine lizard (bottom).

Tylosaurus, which swam in prehistoric seas between 87 and 82 million years ago, was a fierce marine reptile that used its sharp teeth and huge jaws to feed on sharks and other marine reptiles, such as plesiosaurs, as well as fish. A Tylosaurus could grow as long as 50 feet and was a superb swimmer.