Prehistoric aquatic animals are extinct or early species of vertebrates and invertebrates that inhabited marine or freshwater environments from the Cambrian period through the Quaternary. These creatures, including early fish, marine reptiles, and massive sharks, are known primarily through fossil records rather than direct observation.
The Spinosaurus was 50-70 tons and primarly ate fish and what ever else it could eat. It was a semi aquatic animal. It lived in mordern day Egypt, Morocco, and Niger.
The mosasaurus was about 50 feet in legnth and lived during the Late Cretaceous period. They ate almost every thing in the ocean and they were the oceans apex predator.
This animal is called the liaoningosaurus and he was about 30-5 cm. His nickname is the tiny tank. He was discovered in 2001 and lived in modearn day china.
This dinosaur is less known and was a bird like creature. The had sensory oragans that helped them hunt. It's fossils are found in presant day mongolia.