Rytiodus (meaning Rytina, "wrinkled", an old name for Steller's sea cow) is an extinct genus of sirenian, whose fossils have been discovered in France, Europe and Libya.
With a length of , Rytiodus was about twice the size as modern sirenians, surpassed only by Steller's sea cow, which was up to long. Like its closest modern relatives, the dugongs, Rytiodus had a pair of flippers, a streamlined body and a tail fin. Its flattened snout allowed it to feed in shallow coastal waters. Rytiodus had short tusks which it may have used to extract food from the sand.