Macroplata was an early plesiosaur. Their diet consisted of fish.
The dinosaur looked like a brachiosaurus with fins and flippers. i dont know the name sorry. No dinos actually lived in water some nested near water like spinosaurus. but water dwelling lizards werent dinos they were a different specie altogether. the name your looking for is plesiosaurus most likely that is what most people believed the loch ness monster to be : )