Thalattosuchus is an extinct genus of marine crocodyliform that lived in the oceans during the Middle to Late Jurassic.

Fossil specimens referrable to Thalattosuchus are known from Middle-Late Jurassic deposits of England, France and Germany.

Measuring 3–4.5 m (9.8–14.8 ft) in length,[6] Thalattosuchus was similar size to modern crocodiles.

However, it had a streamlined body and a finned tail, making it a more efficient swimmer than modern crocodylian species.

[8] This means that like Cricosaurus it would have been able to "drink" salt-water and eat equally salty prey, such as cephalopods, without dehydrating.