Plesiosaurs were not sauropods, they are not even related to sauropods. They were aquatic animals that belonged to the family group Plesiosauria . They appeared in the late Triassic Period, possibly in the Rhaetian stage, about 205 million year ago and became especially common during the Jurassic Period,
Plesiosaurs came in two main morphological types. The "plesiosauromorph" build, with long necks and small heads and the "pliosauromorph" build with a short neck and a large head. They were apex predators, fast hunters of large prey.
That and sauropods didn't swim all that well. They could if they needed to but would have been clumsy and slow. And as Cal already pointed out, there are a LOT of anatomical differences between them.
Not at all. Plesiosaurs are carnivores. Sauropods ate vegetation. Plesiosaurs are thoroughly aquatic and their limbs are adapted to swimming. Sauropods appear to spend at least some time in water, as their fossilized footprints have been found that appear to show they were walking around on only two legs, which likely means they were using buoyancy to keep the other two legs off the bottom. There is a silly interpretation that says a baby sauropod got so excited that it reared up and ran on two legs. Even so, the sauropods have elephantine feet, not flippers, and they likely just wade, like modern hippos, but they don't swim. Lastly sauropods are archosaurs, meaning they have two temporal openings in the skull, an additional opening in front of the eye known as the antorbital fenestra, and a hole in the jaw bone known as the mandibular fenestra. Plesiosaurs don't have an antorbital fenestra or a mandibular fenestra, and they only have one temporal opening on their skull. That likely means the plesiosaurs are more closely related to turtles than they are to lizards, snakes, dinosaurs, birds and crocodilians.
No. Plesiosaurs were not dinosaurs, and in fact there were no aquatic dinosaurs at all.
Is a plesiosaur like an aquatic saurupod dinosaur ?
