Scientists say the plesiosaur was probably a carnivore, living off the prehistoric fish and other marine reptiles that shared the ocean with it. Stones were found in the area of its stomach; whether they acted as a ballast or helped digestion, it's unlikely anyone will ever know. The animal's long neck probably made fishing easier; it could move its head without having to move its whole body.
But the animal probably had to fend off larger predators -- including the ancestors of the modern shark, which already existed but had trouble competing with larger sea creatures that are now extinct.
"Life for a young plesiosaur, like a young sea turtle, was a little bit tough," said Martin. "You're just trying to survive and get big enough so people will leave you alone. Not any different from being on the school playground."