Sauropterygian

Ecology

Placodonts are thought to have been durophagous, using rounded teeth (including those on the upper and lower jaws, as well as palatal teeth on the roof of the mouth) to crush hard shelled organisms. Members of Eosauropterygia are thought to have been piscivores and carnivores. Sauropterygians were generally marine, though some Jurassic and Cretaceous plesiosaurs are suggested to have inhabited bodies of freshwater. While pleisosaurs were fully aquatic, some non-plesiosaur sauropterygians may have been capable of limited terrestrial locomotion. Plesiosaurs as well as some other sauropterygians including the pachypleurosaur Keichousaurus and the nothosaurs Lariosaurus and Nothosaurus are thought to have been viviparous, bearing live young. At least some other sauropterygians may have been oviparous (egg-laying). Plesiosaurs are suggested to have been endothermic (warm blooded), and other sauropterygians may have had elevated metabolic rates compared to modern ectothermic (cold-blooded) reptiles.