Jurassic Park meets Ice Age with the Nanuqsaurus, T. rex's lesser-known, but equally fearsome Arctic cousin. Sure, it wasn’t as big, but this “polar bear lizard” reigned supreme in the icy prehistoric wilderness, outdating the tiny-armed tyrant-lizard by 1-2 million years. Plus, it was still around six metres long, which is about three times as long as a king size bed.

Don't let the feathers fool you; they weren't for show but for survival, keeping this theropod toasty when it was tearing up the tundra for its next meal. It also had a great sense of smell, which would have been useful in winter during the 24-hour periods of darkness. If you were planning on hiding under a pile of snow for safety, think again.