Marine Reptile Biology

Marine reptiles were reptiles that adapted to a marine environment. They are represented by many different reptile groups. Most notable are the mososaurs, plesiosaurs, icthyosaurs, metriorhynchids and testudines.

Mososaurs: were a group of marine reptiles that were strong air-breathing swimmers. They resembled monitor lizards. The larger mososaurs such as the Tylosaurs were up to 15 meters long.

Plesiosaurs: were marine reptiles with flat bodies, short tails and flippers. Many of the species have a long elongated neck. Some species reached a length of 17 meters.

Testudines (Sea Turtles): are an extinct genus of modern day sea turtles was the Archelon. It had a leathery carapace rather than a shell and grew to about five meters in length.

Metriorhynchids (Crocodiles): Dakosaurus was a crocodile-like marine reptile. They lived out in the seas and grew up to four meters in length.

Icthyosaurs: were marine reptiles that resembled dolphins. Some species possessed a dorsal fin that were not found on the mososaurs or plesiosaurs.  The largest species were 16 meters long.


The prehistoric marine animals are all reptiles. Most belong to groups that are now extinct (e.g. the plesiosaurs). Others like the Archelon were relatives to modern day sea turtles.


The marine reptiles could be found over much of the earth. Most were inhabitants of shallow seas. These prehistoric animals lived from 66 to 200 million years ago.

Marine Reptiles and Humans

Prehistoric marine reptiles are often shown in science fiction movies. However, these creatures died off long before modern humans appeared on the earth.

Improving Your Reading and Thinking Skills

Think for a few moments. Try to recall the major ideas in this article. When you are done, click the box below for a list of main ideas.


How did you do? With practice, you should be able to identify many of the major ideas. You may even discover some important ideas that aren’t listed.


Prehistoric Marine Reptiles, Planet Dinosaur.


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6 comments on "Prehistoric Animals: Marine Reptiles"

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Webster Gabiana

big fish eat small fish becast the big fish is a sea dragon the fish is small the big mut of sea fish can eat 1000 and wile is big weht hes lerge fish

Webster Gabiana

big fish eat small fish


uvoehbos 4 kristna

Webster Gabiana

the dinosor fish is a big fish

Webster Gabiana

the daynasor fish is like donasurfish