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What part of the US did dinosaurs live?

Dinosaurs and Prehistoric Animals by State

Dinosaur National Monument in Utah

Some states in the U.S. were richer in dinosaurs than others. If you live in New Hampshire, for instance, you’re never going to be able to compete with the likes of Utah with its treasure trove of fossils, like the Allosaurus and Utahceratops.

Where Dinosaurs Lived on the Map

However, no matter where you live, you can bet there was at least some prehistoric life there five million, 50 million, or 500 million years ago. Use the list below to see which dinosaurs and prehistoric animals lived in your state during the Paleozoic, Mesozoic, and Cenozoic Eras.

Alabama to Georgia

Stegosaurus skeleton

It shouldn’t be surprising that Alaska, California, and Colorado are the big winners when it comes to the most fossil finds among these states. Alaska has long been poised for migration routes, with California and Colorado on the route to South America.

Every state here does have some interesting finds, though. For instance, the coastal states like Florida, Georgia, and Delaware have a nice selection of marine fossils. Even Connecticut has a good collection of footprints.

Within these states, you’ll find some of the best-known dinosaurs. The Stegosaurus and Tyrannosaurus rex, for instance, have been found in both California and Colorado. Mammoths ranged from Alaska to California, and over to Arkansas and Florida, while sabertooth cats have been found in both California and Florida.

Alabama was home to a large tyrannosaur called Appalachiosaurus, as well as the prehistoric shark Squalicorax. The most famous dinosaur to be discovered in Arizona is the Dilophosaurus.

Hawaii to Maryland

Mammoth fossil

The mega finds of other states are not found in any from this group, though they do offer some very interesting prehistoric revelations. The state with the most actual dinosaur discoveries here is a surprise: Maryland.

As for the other states, Hawaii has only a few prehistoric animals because it was underwater for much of history. Likewise, the Midwestern states were submerged as well, so many of the fossils found in Kansas, Idaho, and Iowa were aquatic. While mammoths have been found in Illinois, Indiana, and Iowa, and mastodons in Kentucky and Louisiana, these were simply not fossil-rich states. No real dinosaurs have been found in many of them.

It’s also interesting to note that the environments and soil of both Louisiana and Maine were not the best for fossil preservation. While more prehistoric life than science knows about may have lived in either state, the fossil records simply didn’t survive.

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Massachusetts to New Jersey

Raptor skeleton

Montana is the fossil hotbed among this set of states. That shouldn’t be much of a surprise, given its proximity to fossil-rich South Dakota and Wyoming. Montana was home to raptors, Triceratops, sauropods, Stegoceras, and so many more.

Other states in this group were not so lucky. Minnesota, Mississippi, and southern New Jersey spent much of prehistory underwater. While marine fossils have been found in those aquatic areas, northern New Jersey did have a fair amount of terrestrial dinosaurs.

The mastodon and mammoth were found in almost all of these states, and Nebraska was once teeming with a diverse prehistoric mammal population. Another surprise is that no complete dinosaurs have been found in Nevada, though plenty have been discovered in neighboring Utah.

New Mexico to South Carolina

Triceratops skeleton at the Los Angeles Natural History Museum.

Where can you find the richest dinosaur fossils among these states? New Mexico is the place you’ll need to go, as its fossils number in the thousands. Oklahoma, thanks to its dry conditions throughout history, is another dinosaur hotspot despite the fact that it was submerged for a significant period of time.

States like New York, Ohio, Oregon, Pennsylvania, and Rhode Island were underwater much of the time, so they primarily have marine and amphibious fossils. Likewise, the Carolinas were often covered by shallow water. Yet, North Carolina has some unique fossil records worth exploring, and South Carolina was home to the saber-toothed tiger.

Pennsylvania may not have dinosaur fossils, but a great many footprints have been found, proving it was a popular area at one time. North Dakota? Scientists have found a Triceratops here, though nothing much else that’s been as complete as the finds from neighboring states.

South Dakota to Wyoming

Tyrannosaurus rex

Are you ready to dive into some of the wealthiest states in terms of fossil records?

Many of these states are in the western and southwestern parts of the U.S. That means the conditions were often ideal for fossil preservation because the bones were high and dry through much of history.

This explains why Utah is a paleontologist’s dream, and the state most noted for its fossil discoveries, including the astonishing 1,500-pound Utahraptor. Likewise, Texas boasts hundreds of complete fossils and Wyoming is a hotbed, with 500 million years of history to be found.

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Though it doesn’t have the number of fossils that those states can claim, South Dakota has diversity on its side. This dinosaur-rich area has produced the Dakotaraptor, Tyrannosaurus rex, Triceratops, Barosaurus, and many other species, large and small, reptilian and mammalian.

As for the other states, Washington and Vermont have mostly marine fossils, West Virginia has amphibians, and Virginia has footprint evidence but no actual dinosaur fossils. Wisconsin’s rocks didn’t preserve fossils well, either. And yet, each of these states does have some fascinating specimens.

Tennessee didn’t have a lot of dinosaurs, but it was home to megafauna, including the camelops, from which all camels are descended.

Giant Ostrich-Like Dinosaurs Once Roamed North America

Riley Black

Enormous, birdlike dinosaurs strutted across ancient Mississippi around 85 million years ago. The precise appearance of these saurian behemoths is as yet unknown. Paleontologists have only found a smattering of leg and foot bones from these massive reptiles. Yet that small collection of fossil remains hints at a little-known realm of dinosaurs that roamed the eastern half of North America during the Cretaceous. The haunts of Tyrannosaurus and Styracosaurus to the west are familiar to experts, but paleontologists are only just beginning to piece together the world of the dinosaurs east of the Mississippi River.

The new fossils were found along Luxapallila Creek in Mississippi. The collection of bones belong to dinosaurs called ornithomimosaurs—“bird mimics” that often resembled ostriches with tails and clawed hands. What makes these bones special, North Carolina Museum of Natural Sciences paleontologist Chinzorig Tsogtbaatar and colleagues propose, is that they represent two as-yet-unknown dinosaur species, one of which attained sizes far larger than any ornithomimosaur found on the continent. The researchers have published their research today in PLOS One.

Despite only representing a few parts of the body, the bones from Mississippi still contain some telltale clues about the dinosaurs those remains belonged to. By comparing those bones to other better-known ornithomimosaurs, as well as studying the microscopic structure of the bones to estimate the growth patterns of the dinosaurs, Tsogtbaatar and co-authors were able to calculate size and age estimates for the dinosaurs in the sample.

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Rather than just one species, the paleontologists propose, the collection from the banks of Luxapallila Creek represent two different ornithomimosaurs. One of them was similar in size to Gallimimus—a dinosaur that has had cameos in the Jurassic Park films and could grow to be 20 feet long and weigh nearly half a ton. At least one of the bones from this ornithomimosaur indicates that the dinosaur was about 14 years old when it died, with the age and body size being similar to other large ornithomimosaurs found elsewhere. But the new study also proposes that an even bigger ostrich-like dinosaur roamed ancient Mississippi.

Some of the foot bones found in Mississippi look comparable in size to one of the strangest dinosaurs ever found. Deinocheirus, the “terrible hands,” was an ornithomimosaur roughly the size of Tyrannosaurus that roamed Cretaceous Mongolia. The duck-beaked dinosaur had immense arms, large claws and a small sail along its back. The larger bones from Mississippi suggest that the creature like Deinocheirus would be the largest ornithomimosaur yet found in North America. “It’s a bit of a surprise to learn that Deinocheirus-sized ornithomimosaurs were also living in North America back in the Cretaceous,” says University of Calgary paleontologist Darla Zelenitsky, who was not involved in the new study. Why such giants have turned up on the eastern half of the continent, rather than in the fossil-rich rocks of the western side, is one of the new questions paleontologists will dig into.

So far, the bones from Mississippi aren’t complete enough to reliably name new species. Nevertheless, Zelenitsky says, “multiple ornithomimosaur species living side by side is interesting.” In other geological formations in western North America, she notes, multiple species of these dinosaurs have been found from the same rock layers and may indicate that ornithomimosaurs preferred different food sources or other habitat requirements to coexist. Future discoveries will help researchers compare how the dinosaur communities differed across the continent. “Hopefully more fossils will be discovered from the east,” Zelenitsky says.

Such discoveries are hard-won. “It’s hard to put into words just how much more we know about dinosaurs in the western U.S. versus the east,” says Smithsonian National Museum of Natural History paleontologist Matthew Carrano, who was not involved in the new paper. Even though some of the earliest major dinosaur discoveries in North America were made on the East Coast, not far from Philadelphia, paleontologists have been focused on the fossil-rich outcrops of western North America for more than 150 years. Scientists have an easier time finding dinosaurs in the west as a result of both natural and human factors.

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The fossil record for dinosaurs across North America isn’t even. Where dinosaurs lived was shaped by a now-vanished ocean. Around 100 million years ago, a warm, shallow sea split North America in two. Known as the Western Interior Seaway, these salty waters divided the continent into a subcontinent known as Laramidia to the west and Appalachia to the east. Wet, lowland habitats along the coasts of these subcontinents generally stood a better chance of preserving dinosaurs than areas that were more inland—until the seaway receded by 66 million years ago. To find dinosaurs, paleontologists working toward the East Coast have to trace the outline of these vanished coasts and hope that vegetation or human construction have not covered up or otherwise obscured the rocks that might contain dinosaurs.

“Most of the rocks are just not very accessible,” Carrano notes. Where forests and vegetation don’t cover over the right rocks in the east, cities and towns do. Even then, he notes, during the last Ice Age immense glacial sheets extended far south and scoured off many of the rocks that formed during the heyday of the dinosaurs. Even when paleontologists in the east find rocks that could preserve dinosaurs, they often locate them on road cuts, construction projects and stream banks. And yet, now and then, eastern fossil hunters come across these rare dinosaurs. Each one is part of a prehistoric tale that is only just beginning to come into focus, surely full of new species that will hopefully be unveiled as paleontologists continue their search.

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Dinosaurs in California

Very few dinosaur fossils have been found in California. Why? Becuase during the time when dinosaurs lived, most of California was covered by the ocean, and any sediments that accumulated in the areas that were dry land have since eroded away. Why do we find dinosaur fossils in areas that were ocean? They may have drowned in a river and been carried out to sea by currents, as happens sometimes to large mammals today. We know that the dinosaur skeletons were deposited in the ocean because we find shells of marine animals where they grew on the dinosaur bones as well as in the surrounding sediments.

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Dinosaur Bones : On the left, you can compare the size of a hadrosaur femur (thigh bone) with the paleontologist who found it. On the right, a Nodosaurus tibia (shin) that later became a home for oysters when the bone was washed out to sea.

Hadrosaurs from California

Hadrosaurs (duck-billed dinosaurs) were common large herbivorous dinosaurs that lived near the end of the Cretaceous, at the same time as Triceratops and Tyrannosaurus. Most of the dinosaur fossils found in California are isolated bones of hadrosaurs, which can be identified by their distinctive arrangement of knobs and muscle attachment scars.

Armored Dinosaur

In 1987, part of the skeleton of a type of armored dinosaur called a nodosaur was found in an excavation near Carlsbad. This was the first of this type of dinosaur found west of the Rocky Mountains, and provided important evidence about connections between the west coast and the interior of the United States. The nodosaur is very similar to species known from Wyoming and Kansas, which supports the idea that dinosaurs on the west coast were part of a cosmopolitan fauna rather than a unique regional group.

Dinosaur Armor : On the left, a portion of the sacral (hip) armor from a nodosaur found in the Pt. Loma Formation of California. On the right is a single large platelike scute, also from a nodosaur’s armor.

Oysters grew on dinosaur skeletons

This armored dinosaur skeleton found in Carlsbad, California, had shells of oysters and rock scallops attached to the bones, in addition to many shells of marine animals in the surrounding rock. (See the picture near the top of this page.) Why were there shells on the bones? Oysters need a solid surface to attach to and live on. On a soft, muddy seafloor, hard surfaces are scarce, and large bones that stick up out of the mud may be the only place for oysters to live. During the Cretaceous, dinosaur bones on the seafloor provided a home for oysters and other animals that needed a solid foundation to grow on.

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