10 Terrifying Prehistoric Animals That Weren't Dinosaurs

By John Kuroski | Edited By Savannah Cox

Published February 19, 2015

Updated November 7, 2023

Liopleurodon

The Jurassic ocean was not a friendly place to live in.

Plesiosaurs were a group of marine reptiles that appeared and disappeared almost at the same time as the dinosaurs, so the popular confusion of the two groups is understandable.

And if there was one plesiosaur you needed to watch out for, it was liopleurodon. This carnivorous beast could weigh more than 3,500 pounds and reach lengths greater than 30 feet, with nearly a quarter of that being its massive skull — complete, of course, with enormous jaws and several rows of razor-sharp teeth.

If you’re brave enough, check out the liopleurodon in action:

Next up: SuperCroc–enough said…

author

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.

editor

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 10, 2025.