* Illustration: Jack Unruh * 1) Carcharodon megalodon

Description A shark twice the length of a great white, this 50-foot killing machine had serrated teeth the size of bowie knives. You would definitely need a bigger boat.

Last seen 1.6 million years ago.

2) Arthropleura armata

Description Creeped out by centipedes? You never would've made it in the Carboniferous era. This 7-foot-long insect was like an even more horrifying and unspeakable version of the Rockettes.

Last seen At the beginning of the Permian period (290 million years ago) — and in your nightmares.

3) Meganeura monyi (Not shown)

Description Dragonflies are already cool. Add a 3-foot wingspan? Awesome.

Last seen The Permian extinction (250 million years ago).

4) Aepyornis maximus

Description The elephant bird stood taller than a basketball hoop, and you could make more than 40 omelets from one of its foot-long eggs. Brunch!

Last seen In the 16th century. Couldn't adjust to the Gregorian calendar?

5) Elasmotherium sibiricum

Description This 20-foot-long Eurasian rhino could run like a horse and gore its enemies with a 6-foot horn. That is one badass unicorn.

Last seen 800,000 years ago.

6) Gigantopithecus blacki

Description Known mostly by the fossilized teeth it left behind, this king of Kongs stood roughly 9 feet tall and weighed around half a ton.

Last seen 300,000 years ago — or possibly in Harry and the Hendersons.

7) Jaekelopterus rhenaniae (Not shown)

Description Don't panic. The so-called giant sea scorpion was actually an arthropod — more like a spider, really. It was 10 feet long, had four eyes, and, in addition to swimming, could walk on land. So that's ... pretty horrible.

Last seen 248 million years ago. Phew!

8) Shonisaurus sikanniensis

Description What's not to love about an aquatic reptile the size of a yacht?

Last seen At the end of the Norian stage (204 million years ago).

9) Doedicurus clavicaudatus

Description Imagine a Volkswagen Beetle with teeth and an enormous spiked tail.

Last seen 15,000 years ago.

10) Ceratogaulus rhinoceros

Description It was a rodent. It had twin tusks growing from its nose. And it burrowed. This explains why there were no good golf courses in the Pliocene epoch.

Last seen 5 million years ago.

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