Extinct Mammals

The megalodon shark has intrigued scientists and the public alike with its nearly unfathomable size and power. Once ruling the ancient oceans, this prehistoric predator is often cited as the largest shark to have ever lived and even inspired a Jason Statham movie franchise.

By Clarissa Mitton

If you like swimming in the ocean, you'll probably be glad to hear that Palaeophis colossaeus, a 40-foot sea snake, has been extinct for millions of years.

By Desiree Bowie

Before the 2003 discovery of Titanoboa cerrejonensis, Gigantophis garstini was known as the largest snake to ever roam the Earth.

By Desiree Bowie

Dimetrodon may look for all the world like a dinosaur, but was actually closer, evolutionarily speaking, to humans. Scientists are still trying to figure what their magnificent sails were used for.

By Mark Mancini

The giant castoroides thrived in the Great Plains, the Great Lakes region, the American South and Alaska. So why did this massive beaver die out?

By Mark Mancini

The extinct Titanoboa snake lived around 66 million to 56 million years ago. These things were massive and could reach 50 feet long and 3 feet wide making them the largest snake ever to have roamed the Earth.

By Mark Mancini & Desiree Bowie

Back in the day, the soupy pre-Amazonian waters were filled with beasts like Stupendemys geographicus, a giant turtle the size of a sensible sedan.

By Jesslyn Shields

The fossilized remains of Simbakubwa kutokaafrika, which means "big lion from Africa," were discovered not once, but twice.

By Mark Mancini

These super-frightening entelodonts (aka hell pigs) once patrolled throughout Eurasia, North America and Africa.

By Mark Mancini

Mid-Jurassic England was teeming with flighted creatures. Now we know it included one pterosaur called Klobiodon rochei.

By Mark Mancini

The battle clearly ended in a slow death for both massive male beasts.

By Mark Mancini

A 220 million-year-old turtle fossil discovered in China is the first of its kind ever to be found.

By Mark Mancini

Massive mastodons roamed lower Kentucky during the last ice age. Jefferson was so fascinated by the creatures he was convinced they still roamed the plains in the 1800s.

By Mark Mancini

Walking evolved not on land but underwater.

By Robert Lamb

A new study found that the Beelzebufo frog had a bite strong enough to take down dinosaurs.

By Mark Mancini

A new study suggests the extinct aquatic reptiles used all four flippers for uniquely efficient underwater motion.

By Mark Mancini

The megapodes were supertall, but that didn't keep them from taking flight.

By Kate Kershner

The method this ancient carnivore employed is unlike anything we see in predators today.

By Jesslyn Shields

The character of King Louie gets a serious primate upgrade in the new Disney live-action-meets-CGI film. Did the ape also serve as inspiration for sasquatch and yeti?

By Laurie L. Dove

The bony fish measured more than six feet long and ate prey using a filtering system similar to that of animals today.

By Christopher Hassiotis

Both of these massive prehistoric creatures belonged to the same family, but they're actually very different species.

By Karen Kirkpatrick

A lot of prehistoric animals were massive, but do we really know why? And is there a larger animal roaming the planet today?

By Karen Kirkpatrick & Sarah Gleim

They were creatures of the air, but they aren't part of the avian family tree — and don't call them dinosaurs. What was life like for the pterosaurs, and what has sparked renewed interest in these flying reptiles?

By Clint Pumphrey

A stunning array of strange and ferocious aquatic beasts patrolled Earth's waters long before they became the stuff of legends and "Jurassic Park" movies. One could eat a great white shark in one gulp.

By Chris Opfer

If you thought sea monsters were just the stuff of myth, you thought wrong. With giant, razor-sharp teeth, ancient cetaceans — the ancestors to modern whales, dolphins and porpoises — make even nightmares seem dull.

By Oisin Curran