Dolichorhynchops Animation

Info below from National Geographic

Dolichorhynchops was a short-necked plesiosaur that lived from the Late Cretaceous (early Turonian to late Campanian stage) of North America.

they used their long, paddle-like flippers to fly through the water like a penguin. The marine reptiles were quick and agile underwater acrobats, with large eyes well adapted to spying small prey. Long, narrow jaws filled with 30 to 40 sharp teeth in a single row allowed Dolichorhynchops to grab its prey but not cut it. Instead, the captured fish were swallowed whole.

Dolichorhynchops grew 12 to 15 feet (4 to 5 meters) long and was probably covered in smooth skin. Its winglike paddles were constructed of almost a hundred tightly packed bones, making them too stiff for use on land but excellent for swimming fast. Though the creatures may have been able to dive deeply in search of prey, the need to breathe air meant most of their time was spent near the water's surface.

The short-necked plesiosaur likely had few enemies, but those that attacked were some of the fiercest monsters of the seas, including sharks with razor-sharp teeth and the giant mosasaur Tylosaurus. One famous Tylosaurus fossil contains the remains of a juvenile Dolichorhynchops inside. And Dolichorhynchops fossils have been found with unborn babies inside, strong evidence they gave birth to live young.