Colonial Americans had an ulterior motive for believing in the flesh-eating mastodon. Unlike the wild continents of Africa and Asia, North America didn't really have any impressively dangerous animals like lions or rhinos. It soon became kind of a joke for the rest of the naturalist world. So the discovery of the mastodon became a source of nationalist pride for the early United States -- a monster so vicious and ferocious that even the rules of basic biology couldn't contain its bloodlust. Thomas Jefferson even assigned Lewis and Clark a secondary mission objective: to find evidence of living mastodons pillaging native villages in the wild uncharted West.

In the meantime, a mastodon skeleton featured in the Philadelphia Museum was altered to look tougher, with its tusks turned downward like a saber-toothed tiger:

Edouard de Montulé, via Common-Place.org

Meanwhile, other researchers came up with even more creative theories:

Alexander Anderson, via Common-Place.org
"What big eyes you have."
"THE BETTER TO STAB YOU WITH."

Of course, today's scientists have a better theory about why the mastodon's teeth look like something out of a grinding mill -- they were for grinding. Grinding up branches and tough vegetable matter. As for the elusive claws, they never found any evidence for that either, but hopefully that won't stop them from making a SyFy original movie out of it.

Ever since the stegosaurus was first discovered in 1877, scientists have had a hard time figuring out exactly how those trademark plates were arranged on its body (or for that matter, how a stegosaurus filled out a trademark application). At first it was thought that they lay flat on the animal's back, covering its vulnerable flanks like a suit of armor:

Frank Bond, via Wikipedia
No evidence suggested that they were covered in spikes, but paleontologists added them
when they were determined to be totally badass.

That shingled-roof formation is actually what gave the stegosaurus its name, and all things considered, it was a fairly reasonable assumption to make. Hell, we have tiny versions of that animal around now. It wasn't until years later that scientists started standing the plates upright, eventually shuffling them around to the version we recognize today.

But if the plates weren't armor, it raised a whole new question: What exactly did these plates do? Were they used for protection? Temperature control? Could they fold those suckers down like wings and take off like an airplane? Haha, that would be ridic-

Ogden Standard-Examiner
"Dude, you forgot to add the totally bitchin' flames decals. I need this to be accurate."

Citing just a little less than zero scientific research to back up his claim, one "Dr. W. H. Ballou" wrote an article in the Ogden Standard-Examiner describing how stegosaurus plates could fold down at will, creating "gliding surfaces immeasurably like those of the planes of to-day." That's right: All it took for a 5-ton behemoth to leap from a cliff and sail gracefully across the Jurassic skies were a series of miniscule back-plates and giant dinosaur balls. To push this madness even further, Ballou asserted that the stegosaurus was a direct ancestor of modern birds (it wasn't, of course) and its plates were actually where wings came from.

As brain-clubbingly stupid as the idea was, it did find some purchase in pop culture. Ballou's Flying Stego-Circus appears to have inspired a scene in Edgar Rice Burroughs' Tarzan at the Earth's Core, where a gliding stegosaurus swoops down from the cliffs to terrorize an explorer, who proceeds to leap off the mountainside with a pair of six-guns and blow the hell out of its tiny brain in a free-falling battle of the ages.

Holy shit! Sounds like we all have some reading to do.

The trouble is, dinosaur books kept teaching the butt-brain hypothesis as a fact for so long that it became firmly lodged all the way up the public's imagination. The myth still pops up from time to time, too ... like in Pacific Rim, where one scientist casually quips that the giant kaiju need two brains to walk around, "like a dinosaur." Not that anyone holds up Pacific Rim as a pillar of scientific authority -- the movie gets a pass for being generally awesome and never giving the slightest shit about realism in the first place.

But how about Discovery Channel specials? In the series Clash of the Dinosaurs, guest paleontologist Matt Wedel discussed the evidence against the two-brain hypothesis in a filmed interview, but since double-brained dinosaurs make for more fascinating TV, the editors deliberately chopped his words until he endorsed the idea. Only after he issued a bitter complaint did Discovery try to set his words straight ... long after the myth was spread to thousands of viewers. What a bunch of butt-brains.

Back in 1911, German paleontologist Otto Jaekel proposed that dimetrodon's protruding back spikes were a defensive weapon against predators -- sort of a giant, reptilian hedgehog. Which is, of course, totally awesome, and we could see why he said it. Then he got a bit carried away making up awesome crap about thunder-lizards and went on to posit that dimetrodon could twist its spine around like a corkscrew, pointing its spikes in all directions like a hellish Tinkertoy wheel.

Dimetrodon also had a vegetarian cousin, edaphosaurus, who was given the same sail-less treatment on the wall of the Berlin Aquarium. The bones of edaphosaurus had little branches sticking out of them, which our old friend Edward Drinker Cope thought might've helped the animal blend in with the undergrowth of a wooded environment.

Berlin Aquarium, via Dinosaurpalaeo
Yep. Totally blending in. Where is the giant friggin' dinosaur in this picture?!

Failing that, Cope had an alternate explanation: Instead of having one big sail, each of edaphosaurus' sailbones supported an individual sail, like the masts on a ship, and these sails could be turned to the wind for the animal to navigate the surface of prehistoric lakes. That's right, the sail of edaphosaurus was thought to be used for actual sailing. Just a big ol' vicious lizard, using his belly as a boat and yachting about with his backfins.

Remember: Both cocaine and heroin used to be totally legal back in the day.

Or how about a beautiful swan, transformed into a terrifying predator that spears fish with its scythe-like arms:

C.M. Kosemen
In fairness, the updated swan paddle boats are pretty kickass.

In reality, the truth about what dinosaurs really looked like is open to as much speculation as your imagination will allow. There's really no way of knowing if dinosaurs had feathers, or turkey crests, or even trunks.

Bill Munns
This is a real idea that scientists have argued about.

In light of this, some authors have put together a book speculating about what might actually pop out if we ever manage to clone dinosaurs like in Jurassic Park:

John Conway

Emiliano Troco

John Conway
At least the feathered T. rex can feel a little less ridiculous.

Nobody's saying the above representations are accurate -- it's pure guesswork. But hard evidence for this sort of thing is cropping up already: A recent discovery of a duck-billed edmontosaurus in Canada came preserved with a flappy rooster's comb on top of its head. It's precisely the sort of bizarre crap that you find on modern animals all the time:

Julius Csotonyi / Current Biology
"The crest is almost stupid-looking enough, but could we draw his snout to look like ridiculous buck teeth, too?"

So basically we're saying that all those terrifying, lean, sleek killing machines from Jurassic Park may have never existed, at least not in the way you think of them. In reality, they could have been a bunch of waddle-having, flappy-skinned, feathered, bright purple goofballs.

We're sorry.

Mr. Yee sticks random bones together to create the Internet's largest comedy fortune cookie and some fairly amusing T-shirts.

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Related Reading: If you think Hunter-Gatherers lived lives of miserable starvation, than you're even more wrong than all those paleontologists. For the hilariously stupid versions of our modern animals, you'd be best served by clicking here. And if you'd rather look at some ancient animals that will give you waking nightmares, this article can oblige. Say hello to the Murderbird with a 40-foot wingspan for us!