Imagine you were born at the time when just terrifying animals covered the entire world? Can't even think of it in dreams also? Yeah, I know you can't! Thank your lucky stars that you'll never run into these terrifying manflesh-eating monsters!
But now at least we can have a look at how they used to look, right? Then, check out these pictures.
20 feet long. Super predators capable of hunting down their prey on land or in the water. You didn't want to see these long necks heading in your direction.
Small but fierce all the same, these early dinosaurs were ancestors of modern birds but with rather more bite.
These bad boys would have been bigger than our modern elephants, and we have no idea how friendly they would have been to visitors.
This guy came in at over 60 feet in length! He'd have been big enough and bad enough to scoff down a shark like a tasty snack, and as far as we can tell, he did just that.
Forget the T-rex. At over 30 feet, this giant lizard was probably the biggest land predator that ever lived.
Another shark hunting bad boy, and as you can see, you'd have been a nice appetizer before the main course.
Lurking under the water and over 40-feet long, these super-crocodiles hunted whatever they felt like hunting. Would you have argued with them?
Over 40 feet tall, the Saurinops hunted the plains of a prehistoric Mexico. There'd have been no need for Trump's wall if they were around today... everybody would already have left Mexico.
The talons on this lovely raptor were over three feet long, and it would have been able to disembowel predators, but it was, in essence, a big chicken and didn't hunt prey itself.
You can see that the modern Ostrich or Emu had its prehistoric equivalents, too. The Kelenken existed about 15 million years before us and after the dinosaurs were gone. They'd have been fast and very, very dangerous.