Marine reptile

Marine reptiles are reptiles which have become secondarily adapted for an aquatic or semi-aquatic life in a marine environment.

The earliest marine reptiles arose in the Permian period during the Paleozoic era. During the Mesozoic era, many groups of reptiles became adapted to life in the seas, including such familiar clades as the ichthyosaurs, plesiosaurs, placodonts, and mosasaurs.

After the first mass extinction at the end of the Cretaceous period, marine reptiles are less numerous, consisting largely of sea turtles, sea snakes, Marine Iguanas and some species of crocodylians.

Some marine reptiles, such as ichthyosaurs and mosasaurs, rarely if ever ventured onto land and gave birth in the water. Others, such as sea turtles and saltwater crocodiles, still return to shore to lay their eggs.