“Lizard of the Meuse River”
Late Cretaceous, 70-66 million years ago

Mosasaurus was a type of extinct marine reptile similar to a giant monitor lizard, but with fins. It would have been an apex predator of the Cretaceous seas, growing to almost 60 feet long!
The first Mosasaurus fossil was found in 1764 (about 50 years before the first dinosaur remains), though it wasn’t recognized as a marine reptile until around 1800 (roughly 40 years before the term “dinosaur” was coined). While it was instrumental in the understanding of extinction – and by extension modern biology as we know it – Mosasaurus was largely forgotten until its triumphant rediscovery in November 2014 as part of a movie trailer.

Of all the creatures of Hell’s Aquarium, none were as nightmarish as the Mosasaurs. One such Mosasaur, Tylosaurus proriger, grew to be fifteen metres long and weighed in at about seven metric tonnes - that is, if it made it that far. Mosasaurs ate almost anything that moved - fish, turtles, sharks… and even other Mosasaurs. Life in Hell’s Aquarium wasn’t a walk in the park.

This Tylosaurus got off lucky, though not unscathed. A chunk of her left hind fin is missing - perhaps torn off by an older Mosasaur - but this is barely a scratch. Now she is the biggest set of teeth for miles around, and this watery kingdom is hers.

Hope you enjoy!


The Mesozoic Park: Mosasaurus

Common name: Mosasaurus (moe-zah-sore-us) Size: ~15ft (maximum 59ft) Age: Cretaceous (70-66 MYA) Geographic range: Global (including freshwater) Liked: Eating EVERYTHING. Disliked: Diving/chasing/jumping Taxonomy: Animalia > Chordata > Reptilia > Squamata > Mosasauridae > Mosasaurini > Mosasaurus

The mosasaurus was the first of ~77 known mosasaur genera to be named. Averaging in at approximately 15ft long and heavily robust, the mosasaurus was a prevailing carnivore in the late Cretaceous period. Often mistaken for a Dinosaur (class Dinosauria), this water-dwelling, air-breathing vertebrate is actually considered to be a serpent/lizard (class Reptilia).

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“Globe teeth”
Late Cretaceous, 70-60 million years ago

Whereas most mosasaurs had sharp, flesh-tearing teeth, Globidens’ teeth were rounded and acted more like nutcrackers. Such adaptations would’ve made short work of ammonites, nautiloids, and other shelled denizens of the Cretaceous seas. It is named partially for its specialized dentition, but mostly for its corporate sponsor, GlobiDens™ International, LLC.