Paleontologists have identified literally thousands of prehistoric animals—and for every memorable dinosaur such as Tyrannotitan or Raptorex, there are three or four prehistoric beasts saddled with clumsy nearly unpronounceable names including Opisthocoelicaudia or Dolichorhynchops. Here are 10 of the most difficult names of early species to say and spell.

01 of 10 Allaeochelys Allaeochelys Fossil -- Museum of Natural History, Freiburg. Ghedoghedo/Wikimedia Commons This prehistoric turtle (pronounced AH-lah-ee-OCK-ell-is or AH-la-EE-oh-KELL-iss, take your pick) briefly made headlines when paleontologists identified nine separate specimens of males and females that were fossilized in the act of mating. Why were so many casualties in flagrante delicto? Perhaps they were exceptionally slow in their reproductive rituals–or could it have been that they expired of old age trying to pronounce one another's names?

02 of 10 Epidexipteryx Illustration of the maniraptoran ((dinosaur Epidexipteryx, here depicted with hands which is characteristic for members of the theropod family Scansoriopterygidae. Conty/Wikimedia Commons Evolutionarily speaking, Epidexipteryx (EP-ih-dex-IP-teh-ricks) seems to have existed for the sole purpose of making the closely related Archaeopteryx seem more pronounceable. This "dino-bird" predated its more famous cousin by millions of years and was equipped with a spray of strictly ornamental feathers jutting from its posterior. Its name, Greek for "display feather," evokes a genetically engineered nasal decongestant, but Epidexipteryx may well have been a crucial link in the evolutionary chain connecting ancient dinosaurs and modern birds.

03 of 10 Huehuecanauhtlus Huehuecanauhtlus tiquichensis, a hadrosauroid dinosaur from the Santonian (Late Cretaceous) of Michoacán, Mexico. Karkemish/Wikimedie Commons Since Huehuecanauhtlus is nearly impossible to spell or pronounce (WAY-way-can-OUT-luss, anyone?), you may be wondering what language the name of this duck-billed dinosaur—which logically enough, translates as "ancient duck"—is derived from. The answer is Aztec—the same tongue that gave us the giant pterosaur Quetzalcoatlus. As you may have surmised, the "type fossil" of Huehuecanauhtlus was discovered in Mexico, from whence Aztec civilization disappeared hundreds of years ago under the onslaught of European settlers.

04 of 10 Onychonycteris Esqueleto y reconstrucción del Onychonycteris Finneyi. Loana Riboli/Wikimedia Commons Onychonycteris (OH-nick-oh-NICK-teh-riss) is another good example of how a perfectly reasonable English phrase (in this case, "clawed bat") can be rendered nearly unpronounceable when translated into standard Greek genus format. You may not be surprised to learn that this Eocene bat was closely related to Icaronycteris, but paleontologists were intrigued to discover that the slightly earlier Onychonycteris had a more primitive inner-ear structure—meaning that bats likely evolved the ability to fly before they evolved the ability to echolocate.

05 of 10 Phlegethontia Life restoration of Phlegethontia longissima. Smokeybjb/Wikimedia Commons The most frustrating thing about Phlegethontia (FLEG-eh-THON-tee-ah) is trying to figure out what this prehistoric creature's name is supposed to mean. The "phleg" part evokes the Greek root for "phlegm" and "phlegmatic," but "thont?" It's a mystery, as you can determine for yourself with a quick web search. Whatever the case, the three-foot-long Phlegethontia was a limbless amphibian that prowled the swamps of late Carboniferous Eurasia. Over a century ago, it was known by the slightly more pronounceable name Dolichosoma, meaning "long body."

06 of 10 Phthinosuchus Phthinosuchus discors, author - D. Bogdanov. DiBgd/Wikimedia Commons Yet another prehistoric animal that you wouldn't want to pronounce with a mouthful of crackers, Phthinosuchus (fffTHINE-oh-SOO-kuss) shares the same double-diphthong spelling as the marine reptile Ophthalmosaurus, with the added burden of being much less well known. This mysterious therapsid, or "mammal-like reptile," of the late Permian period is represented in the fossil record by only a single skull, so, fortunately, it doesn't come up all that often in cocktail-party conversation at paleontology conventions.

07 of 10 Propliopithecus Propliopithecus. Noeliria123/Wiki Prehistorico If you take it slow and phonetically, Propliopithecus (PRO-ply-oh-pih-THECK-uss) is fairly easy to spell and pronounce. The trouble comes when you try to name-drop this prehistoric primate two or three times in the same sentence, at which point you may wonder why people around you are starting to giggle. (For the record, the middle Oligocene Propliopithecus was named with reference to the much later, and slightly easier to pronounce, Pliopithecus, and it may yet revert to the genus name Aegyptopithecus if the fossil evidence so indicates).

08 of 10 Theiophytalia Theiophytalia. Nobu Tamura The American paleontologist Othniel C. Marsh probably thought he was being erudite and classical-minded when he named this dinosaur Theiophytalia (THEE-oh-fie-TAL-ya), Greek for "garden of the gods." All he accomplished, though, was to relegate this otherwise plain-vanilla ornithopod to the dustbins of paleontological history. Not many papers have been written about Theiophytalia, possibly because nobody wants to exhaust the resources of their online spell-checking software—or have to pronounce this name during a live presentation.

09 of 10 Thililua Fossil of Thililua longicollis -- NAtional Museum of Nature and Science, Tokyo Japan. Momotarou2012/Wikimedia Commons The marine reptile Thililua (thi-lih-LOO-ah) packs a lot of syllables into its modest frame, and all those similar-looking i's and l's are not much of a help, either. Still, when you say it out loud, this is one of the most euphoniously named of all prehistoric creatures (another candidate would be a runner-up for this list, the sauropod dinosaur Suuwassea). Rather than being assembled from Greek roots, Thililua was named after an ancient deity of the northern African Berbers, on whose territory the remains of this plesiosaur (a type of marine reptile) were discovered.