Dinosaur National Monument

Dinosaur National Monument in Colorado and Utah is not a typical dinosaur museum. Instead of the usual exhibit of entire, assembled dinosaur skeletons, the site contains a cliff face of jumbled fossil bones. The quarry site, which was designated a national monument in 1915, is one of the largest known deposits of dinosaur fossil bones in the world.

At first, the cliffs were excavated and loads of fossils shipped to museums around the country, where they were carefully reconstructed into complete skeletons. The fossil bones that remain on-site have been left embedded in the stone, with only their surfaces exposed. What is visible are the bones as they have been randomly collected by the forces of nature.

Around 145 million years ago, this area, where the Yampa and Green rivers now meet, was excellent dinosaur habitat. Several large rivers and many streams crossed the low-lying plain. Ferns, cycads, club mosses, and clumps of tall conifers covered the land, providing forage for large vegetarians. Apatosaurus (better known as Brontosaurus), Diplodocus, Stegosaurus, and other plant eaters thrived, as did Allosaurus and other sharp-toothed carnivores.

Dinosaur National Monument
©National Park Service
The landscape of the Dinosaur National Monument, located in Colorado
and Utah, contains one of the largest fossil deposits in the world.

As dinosaurs died in or near an ancient river, their bodies were carried downstream, where sometimes they were deposited near the inside of a river bend. Over time, the remains of the dinosaurs mixed with those of turtles, crocodiles, and other river dwellers, and all the fossils were preserved in the sand. Flexible body parts, such as long tails and necks, trail downstream in the river bed, indicating the direction of flow of the ancient river.

Tons of sand and volcanic ash up to one mile thick eventually covered and compressed the bones. As the Rocky Mountains began to rise to the east, the upheaval and erosion over millions of years exposed the ancient river bed and its bounty of fossils.

Intriguing exhibits, a short film, and ranger programs introduce visitors to the thousands of fossils caught in the sandstone face that makes up one wall of the Dinosaur Quarry Visitor Center. In the summer, paleontologists can be seen working at the site.

In addition to the quarry, the monument encompasses more than 210,000 acres of canyon country. A number of hiking trails cross the basin-and-plateau land. Sagebrush, greasewood, and saltbush survive in the dry, lower elevations, and "pygmy forests" of pinyon pine and juniper, along with stands of Douglas fir, grow higher up, providing habit for a number of animals, including Canada geese, deer, elk, mountain lions, and bighorn sheep.

Fascinating petroglyphs carved by the prehistoric Fremont people decorate cliff walls, while green oases of cottonwoods and box elders trail through the park, following the rivers and their canyons.

Dinosaur Quarry

Dinosaur Quarry was discovered in 1909 by a paleontologist named Earl Douglass from the Carnegie Museum in Pittsburgh. Though fur trader William H. Ashley and explorer-scientist John Wesley Powell had each floated down the Green River near the ridge years earlier without noticing the fossils, Douglass knew what to look for. He was aware that similar rocks in Colorado and Wyoming had contained great collections of dinosaur bones, so he began to search this area in 1908. On August 17, 1909, he wrote in his diary: "At last, in the top of the ledge... I saw eight of the tail bones of a Brontosaurus in exact position. It was a beautiful sight."

Dinosaur National Monument Information

Address: 4545 E. Highway 40
Dinosaur, CO 81610
Telephone: 435/781-7700
Hours of Operation: Temporary Visitor Center open daily, 8:30 a.m. - 4:30 p.m., with extended hours during the summer; Canyon Area Visitor Center open March 1 through late October; hours vary
Admission: $10 per vehicle or $5 per person

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To learn more about national national monuments, memorials, and historic sites, and other travel destinations in North America, visit:



Eric Peterson is a Denver-based freelance writer who has contributed to numerous guidebooks about the Western United States.