10 Terrifying Prehistoric Animals — That Weren’t Dinosaurs

Published February 19, 2015
Updated November 7, 2023


Prehistoric Sea Creatures

A mosasaurus as depicted in Jurassic World.

Like plesiosaurs, mosasaurs were marine reptiles, and not technically dinosaurs. At almost 60 feet in length, mosasaurus was the biggest of the bunch.

In fact, it was one of the most dangerous creatures prowling the waters throughout the entire Cretaceous period. It looked like a massive crocodile (particularly the head), only equipped with fins, which — terrifyingly — allowed it better mobility in the water.

Thanks to the Discovery Channel, we can see what a mosasaur looks like when “upset”:

Next up: Paleontologists have called it the greatest apex predator of all time…

John Kuroski
John Kuroski is the editorial director of All That's Interesting. He graduated from New York University with a degree in history, earning a place in the Phi Alpha Theta honor society for history students. An editor at All That's Interesting since 2015, his areas of interest include modern history and true crime.
Savannah Cox
Savannah Cox holds a Master's in International Affairs from The New School as well as a PhD from the University of California, Berkeley, and now serves as an Assistant Professor at the University of Sheffield. Her work as a writer has also appeared on DNAinfo.
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Kuroski, John. "10 Terrifying Prehistoric Animals — That Weren’t Dinosaurs." AllThatsInteresting.com, February 19, 2015, https://allthatsinteresting.com/terrifying-prehistoric-creatures. Accessed May 23, 2024.