The Best Dinosaur in the JURASSIC WORLD Trailer Isn’t Actually a Dinosaur

Up until the dinosaurs died, a 50-foot long lizard was patrolling the seas for 27 million years. In Jurassic WorldOpens in a new tab, they are splashing park-goers like Shamu.Descended from a major group of reptiles that returned to the sea, Mosasaurs were ferocious oceanic and freshwater predators that quickly diversified and dominated the oceans during the Late Cretaceous period. The largest of these mosasaurs — HainosaurusOpens in a new tab — could reach up to 50-feet long, and resembled a komodo dragon with flippers stuck on it. Mosasaurs had double-jointed jaws with flexible, snake-like heads, and they propelled their sometimes gigantic bodies with side-to-side motions like an anaconda or sea snake slipping through the water.

But they weren’t dinosaurs.

112614_Mosasaur_FossilOpens in a new tabYes, this was a real creature (and the eye does have bony rings in itOpens in a new tab).

During the last age of the dinosaurs, mosasaurs burst onto the aquatic scene as other dominant ocean lizards, IchthyosaursOpens in a new tab and PlesiosaursOpens in a new tab (laparas for you pokemaniacs), met their demise. The mosasaurs, however, did not evolve from fully-aquatic ancestors. They are believed to be descended from within a family of semi-aquatic lizards called AigialosauridaeOpens in a new tab, though the fossil record is a bit spotty on the precise transition.

112614_Mosasaur_LineageOpens in a new tabThese marine lizards were more closely related to, well, modern lizards than dinosaursOpens in a new tab (very simplified). Image: Arvind Pillai.

Unlike what we see in the Jurassic World trailer, these predators likely had forked tonguesOpens in a new tab like modern snakes and lizards do. But the largest mosasaurs were indeed gigantic — 50-feet long and 15 tons in weight — though the family had a range of species that got as small as 3-feet long. Some were the size of a large dog, but with gigantic teeth and a flexible head and it would eat your dog. Mosasaurs did probably eat sharks too, even though prehistoric sharks could often turn the tablesOpens in a new tab.112614_Mosasaur_CloseUpOpens in a new tabHow much money would you pay to see a mosasaur water show? Like, all the money? Me too.–IMAGES: Arvind PillaiOpens in a new tab; Mosasaurus at Natural History Museum of MaastrichtOpens in a new tab by GhedoghedoOpens in a new tabDon’t miss our breakdown of the Jurassic World trailer from yesterday’s Nerdist News!