If you think the modern animal kingdom is frightening, then wait until you get a load of the animals that existed millions of years ago. Most of the scariest creatures that used to really exist are related to animals we live with now; however, the animals we're glad are extinct were bigger and scarier - and for some reason, most of them had buzzsaw-like teeth.
Many of the scariest extinct animals are similar to dinosaurs. Some existed alongside the T-Rex, while others arrived post-asteroid and exhibited some of the dinosaur’s most frightening attributes. Many of the massive extinct animals have descendants alive today (a large number of them live in Australia), although they’re hardly as dangerous as their ancestors from millions of years ago.
Size: 50 feet long
When They Lived: 400 million years ago
Distinguishing Features: Megalodons were big boys. Not only were they 50 feet in length, but they also weighed up to 50 tons. Because sharks are made of cartilage, they don't leave fossils behind. Instead, researchers have to use tooth size as a comparison tool.
Size: 36 feet long
When They Lived: 72-83 million years ago
Size: 40 feet long
When They Lived: 58 million years ago
Distinguishing Features: Obviously this is a very large snake. Not only did it grow to 40 feet in length, but it also weighed more than a ton. These giant snakes ruled the jungle and moved through swamps with ease.
Size: About 3 feet long
When They Lived: Between 6 million and 10 million years ago
Distinguishing Features: Piranhas are scary; Megapiranha was downright terrifying. Not only were these fish about 3 feet long, but they also weighed between 20 and 30 pounds. That's a big fish. Aside from its actual size, Megapiranha's jaw could generate up to 72 pounds of force. That means it could take a huge bite out of any animal that was unlucky enough to pass by.