1 of 13 Fact can be as bizarre as fiction Photo: zak mc /Flickr Some animals are so exotic that their initial discovery is difficult to comprehend. Stories of dragons, sea serpents or mermaids may seem like tall tales to us today, but most mythical beasts actually have a basis in reality. In fact, many creatures of lore are founded on real living or extinct animals. To prove it, here's our list of animals that have been mistaken for mythical creatures. You might be surprised to discover that fact is often just as bizarre as fiction.

2 of 13 Okapis Photo: Jiri Hrebicek/Shutterstock One of the animals believed by some to be the mythical origin of the unicorn is the okapi. These bizarre deer-like mammals, which live in the rain forests of Africa, appear to be the combination of a giraffe, a zebra and an antelope. If seen from a distance they can resemble zebras or horses, and male okapis have two horns which, when viewed from the side, can appear as one. Of course, any number of creatures could have reinforced the myth of the unicorn. For instance, when European explorers first encountered narwhal tusks, many believed they were evidence of unicorns. But it's possible the elusive okapi started it all.

3 of 13 Gigantopithecus Photo: auxesis /Flickr They may look like Bigfoot, but these extinct creatures were real apes that roamed the forests of Asia as recently as 300,000 years ago. In fact, the Gigantopithecus was the largest ape that ever lived, standing up to 10 feet tall and weighing well over 1,000 pounds. Some anthropologists believe that Gigantopithecus was bipedal, making quite an impression on our hominid ancestors. Fossil remains of Gigantopithecus could have led to the myth of the Yeti, and some fringe researchers believe it's possible populations of the creature may have persisted into recent times, giving root to the Bigfoot legend.

4 of 13 Giant oarfish Photo: Wm. Leo Smith /Wikimedia Commons The giant oarfish, also known as the king of herrings, is the world's longest bony fish. Looking at this unbelievable animal, you might understand how it could give rise to tall tales of sea serpents. Growing upward of 55 feet long, the giant oarfish spends most of its time slithering through the ocean's deepest depths (between 300 and 1,000 meters), and is rarely seen on the surface. But when it does occasionally come up, it's the stuff of legend.

5 of 13 Dugongs and manatees Photo: simamusume/Shutterstock Christopher Columbus, while sailing near Haiti, believed he was looking at a mermaid when he saw his first manatee. He got close enough to note that they were "not as pretty as they are depicted, for somehow in the face they look like men." Closely related to the portly manatee, which prefers estuarine or fresh waters, the dugong is slimmer and more strictly a marine mammal, and is the likely suspect for most mermaid origin stories. To be fair to the manatee, not everyone has been quite so dismissive as Columbus. Explorer John Smith (who famously caused Pocahontas to swoon) also reported seeing a mermaid once, noting that it was "by no means unattractive."

6 of 13 Theropods Photo: kevindooley /Flickr The most terrifying of all dinosaurs were the theropods, a group that encompasses the fierce T-Rex. You can only imagine what early fossil hunters must have thought when they stumbled upon theropod bones. In fact, many experts believe that dinosaur remains may have given rise to belief in dragons, as ancient cultures attempted to account for fossils of creatures they had never seen alive. As for all the mythology behind fire-breathing and treasure hoarding, you can probably chalk that up to human imagination.

7 of 13 Colossal squid Photo: Stephanemartin /Wikimedia Commons The legend of the mythical sea monster known as the Kraken, which in most depictions resembles a mammoth cephalopod, is likely derived from sightings of giant or colossal squid. The colossal squid's limbs are equipped with sharp hooks, some of which swivel. Since these beasts prefer to dwell in deep ocean waters, sightings of giant squid are rare but possible.

8 of 13 Protoceratops Photo: Kabacchi /Flickr The protoceratops was a sheep-sized dinosaur that once roamed the land in what is now Mongolia. The four-legged creature had an enormous head and a parrot-like beak, which early fossil hunters likely mistook for the remains of a griffin — a mythical beast said to have the head of an eagle and the body of a lion. Even today, protoceratops fossils can be found all over the Gobi desert, and given the skeletal form of the animal's fossils, it's easy to see how the griffin theory was originally conceived.

9 of 13 Flamingos Photo: Aaron Logan /Wikimedia Commons The flaming hues of pink and red that form a flamingo's plumage can be so striking that many believe the birds could have given rise to the legend of the phoenix. A sacred firebird, the mythical phoenix was first identified by ancient Egyptians as a heron-like bird with crimson feathers. In fact, flamingos spend much of their time wading in salt flats, where convection currents are known to swell and flicker much like a flame.

10 of 13 Dwarf elephants Photo: wonker /Flickr Look at this elephant skull out of context, and you might believe you were looking at the remains of a giant one-eyed beast. In fact, prehistoric dwarf elephants (with skulls much smaller than modern elephants) used to roam the Mediterranean islands, including Crete, Sicily, Malta and Cyprus. Extinct by the time ancient Greeks encountered their skulls and remains, these elephants are likely the origin of the mythical creature known as Cyclops. The "eye socket" on the skull is actually the central nasal cavity for their trunks.

11 of 13 Diprotodon Photo: © N. Tamura /Wikimedia Commons The diprotodon, also known as the giant wombat, was the largest marsupial that ever lived. The enormous creature was known to exist as recently as 40,000 years ago, which means that it would have been around by the time humans migrated to Australia. Some experts suggest the diprotodon is the origin of the mythical monster known to Australian Aboriginals as the bunyip. The diprotodon still lives on in the rich cultural memory of Aboriginal lore, and some tribes identify diprotodon fossils as "bunyip bones". Both creatures share some key behaviors, such as lurking in swamps and billabongs.

12 of 13 Plesiosaurus Photo: Dmitry Bogdanov /Wikimedia Commons One of the most famous mythical creatures, the Loch Ness Monster, has an equally notorious basis theory: that the beast is a living plesiosaur. Sightings of Nessie have often taken the form of a broad-humped and long-necked aquatic creature, which fits the plesiosaur description. Although most experts believe that plesiosaurs went extinct along with most dinosaurs at the end of the Cretaceous Period, there are fringe believers who think populations of the beast may have lingered into modern times. There's certainly no shortage of amateur sightings.