“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.