Mosasaurs
70 million years ago
Giant Mosasaurs ate and killed them.
They lived in the Late-Triassic and the Cretaceous, but disappeared through the Jurassic!
Certain kinds of sharks and maybe killer whales do, and in the past, mosasaurs and plesiosaurs did.
An Aigialosaurus specimen was found with eggs developing inside of it. This is proof that mosasaurs did give birth to live young, which developed in eggs that the mother held in her body. Pliosaurs, also known as short necked plesiosaurs, also gave birth to live young.
They include Ankylosaurs (the armored dinosaurs), Mosasaurs, and Plesiosaurs (both marine reptilian groups).
First of all there is no proof that mosasaurs existed so if they did exist, then no they would be dead due to change of water temperatures
No. Plesiosaurs were marine reptiles, not dinosaurs. Saurichians were one of the two main groups of dinosaurs (which included sauropods - such as Apatosaurus - and theropods - such as T. rex).
There were no ocean dwelling dinosaurs. Large marine reptiles that are often thought of as dinosaurs include plesiosaurs, pliosaurs, mosasaurs, and icthyosaurs.
Yes, crocodiles, caimans, alligators, gavials, saltwater crocodiles, sea turtles, terapins, hellbenders, and marine iguanas, are some that live today. During the mesozoic era, many reptiles lived in the water, like plesiosaurs, placodonts, mosasaurs, sea turtles, nothosaurs, thalattosuchians ichthyosaurs, and more.
It is probally the mosasaurs. During their times, it was the most dominant and succesful predator ever. Also, it was unkillable.