Extinct Mammals

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

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

Paleontologists in China hit the jackpot of fossilized pterosaur eggs.

By Mark Mancini

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

By Mark Mancini

Instead of a mouth, the hell ant had blades and a metal horn to catch its prey. Ouch.

By Melanie Radzicki McManus

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

By Mark Mancini

Accidentally tripping on and discovering the fossilized skull of an extinct giant elephant seems like a 9-year-old's dream come true.

By Christopher Hassiotis

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

Scientists thought climate and ecological change was the culprit, but a new study suggests otherwise.

By Christopher Hassiotis

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

Scientists discover male animals flashed sabers far longer than first thought.

By Adrian Rogers

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

By Karen Kirkpatrick

If you've been curious about why dinosaurs and other prehistoric animals were so massive, know that paleontologists are still on the case.

By Karen Kirkpatrick

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