Science, Tech, Math › Animals & Nature The Dinosaurs and Prehistoric Animals of Missouri Share Flipboard Email Print Animals & Nature Dinosaurs Basics Paleontologists Carnivores Dinosaurs & Birds Herbivores Marine Reptiles Prehistoric Mammals Amphibians Birds Habitat Profiles Mammals Reptiles Wildlife Conservation Insects Marine Life Forestry Evolution View More By Bob Strauss Science Writer B.S., Cornell University Bob Strauss is a science writer and the author of several books, including "The Big Book of What, How and Why" and "A Field Guide to the Dinosaurs of North America." our editorial process Bob Strauss Updated March 03, 2019 Like many states in the U.S., Missouri has a lopsided geologic history: there are tons of fossils dating to the Paleozoic Era, hundreds of millions of years ago, and the late Pleistocene epoch, about 50,000 years ago, but not much from the vast stretch of time in between. But even though not many dinosaurs have been discovered in the Show Me State, Missouri isn't lacking for other kinds of prehistoric animals, as you can learn by perusing the following slides. 01 of 05 Hypsibema Rick Hebenstreit/Flickr/CC BY-SA 2.0 The official state dinosaur of Missouri, Hypsibema is, alas, a nomen dubium—that is, a type of dinosaur that paleontologists believe duplicates, or was technically a species of, an already-existing genus. However it winds up being classified, we do know that Hypsibema was a respectably sized hadrosaur (duck-billed dinosaur) that roamed the plains and woodlands of Missouri about 75 million years ago, during the late Cretaceous period. 02 of 05 The American Mastodon Corbis via Getty Images / Getty Images Eastern Missouri is the home of Mastodon State Historic Park, which—you guessed it—is famous for its American Mastodon fossils dating from the late Pleistocene epoch. Amazingly, researchers at this park have discovered crude stone spear points associated with Mastodon bones—direct proof that the Native Americans of Missouri (related to the Clovis civilization of the southwestern U.S.) hunted Mastodons for their meat and pelts, between 14,000 and 10,000 years ago. 03 of 05 Falcatus Smokeybjb/Wikimedia Commons/CC BY-SA 3.0 Missouri is famous for its plentiful fossils of Falcatus, discovered near St. Louis in the late 19th century (this prehistoric shark initially went by the name Physonemus, and changed to Falcatus after subsequent discoveries in Montana). Paleontologists have established that this tiny, foot-long predator of the Carboniferous period was sexually dimorphic: the males had narrow, sickle-shaped spines jutting out of the top of their heads, which they presumably used to mate with females. 04 of 05 Small Marine Organisms Typical crinoid fossil. James St. John/Flickr/CC BY 2.0 Like many states in the American midwest, Missouri is known for its tiny, marine fossils dating from the Paleozoic Era, about 400 million years ago. These creatures include brachiopods, echinoderms, mollusks, corals, and crinoids—the last typified by the official state fossil of Missouri, the tiny, tentacled Delocrinus. And, of course, Missouri is rich in ancient ammonoids and trilobites, large, shelled crustaceans that preyed on these tiny creatures (and were preyed on themselves by fish and sharks). 05 of 05 Various Megafauna Mammals Giant beaver. C. Horwitz/Wikimedia Commons/CC BY-SA 3.0 The American Mastodon (see slide #3) wasn't the only plus-sized mammal to traverse Missouri during the Pleistocene epoch. The Woolly Mammoth was also present, albeit in lesser numbers, as well as sloths, tapirs, armadillos, beavers, and porcupines. In fact, according to a tradition of Missouri's Osage tribe, there was once a war between "monsters" that approached from the east and the local wildlife, a story that may well have originated in an unexpected migration of giant mammals thousands of years ago.