Mosasaurs were relatives of the modern monitor lizards, but they differed from monitors in being up to 10 m in length. Mosasaurs had a long snaky body, which was flattened to help them swim, and paddle-like limbs. These animals were so modified to suit their marine environment that they could probably not venture onto the land. They are known to have fed on ammonites, because mosasaurs teeth marks have been found on the fossil shells of these creatures. Mosasaurs died out at about the same time as the dinosaurs.
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