Pachystropheus rhaeticus — one of the last thalattosaur, a large sea-lizard that behaved like an otter — was able to move on land, but was most likely a primarily marine predator with an ecological niche distinct from coeval marine reptiles (placodonts, ichthyosaurs) and carnivorous fishes (hybodont sharks, actinopterygians). Life restoration of Thalattosaurus alexandrae. Image credit: Nobu Tamura, http://spinops.blogspot.ca. Pachystropheus...