The Dinosaur Ridge in Morrison

The Dinosaur Ridge in Morrison, in the state of Colorado, is one of the world’s most famous dinosaur sites. Discovered in 1877 by Arthur Lakes, it was here where some of the best-known dinosaurs, including Apatosaurus, Diplodocus, Stegosaurus, and Allosaurus, were first identified. Bones from Stegosaurus and Apatosaurus are still exposed in the rocks today, and can be felt and touched. Another attraction is a stony incline, exposed in 1937, with hundreds of dinosaur footprints fossilized in the rock. These tracks were made by Iguanodon-like herbivores and ostrich-sized carnivores about 100 million years ago, when the dinosaurs were migrating north and south along the shore of the ancient inland sea.

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Dinosaur footprints at Dinosaur Ridge in Morrison. Photo credit: Mark Ryan/Flickr

Between 145 million to 201 million years ago, the area that is now Colorado consisted of a low plain crossed by slow-moving rivers. Sauropod dinosaurs lived and died along the rivers. Sometimes their bones were fossilized in the river mud and sand. Later, during the Cretaceous period, eastern Colorado was submerged under an inland sea from about 110 million to 70 million years ago. During this time, Iguanodon dinosaurs migrated along the western edge of the inland sea. Then about 65 million years ago the sea drained, and a sudden uplift called the Laramide orogeny formed huge mountains where the Rockies are today. This activity also tipped the old inland seabed at an angle, exposing the fossils at what is now Dinosaur Ridge.

This area is now recognized for its historical and scientific significance, and was designated the “Morrison Fossil Area National Natural Landmark” by the National Park Service. Today, the site features an Exhibit Hall with displays about the dinosaurs found at the site, and a 1.5-mile trail taking visitors through 15 fossil sites spread over the area.

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Photo credit: James St. John/Flickr

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The footprints are colored using charcoal to help visitors see the tracks in the sandstone. Photo credit: James St. John/Flickr

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One of several dinosaur footprint at Dinosaur Ridge. Instead of a depression in the rock, this footprint is raised. The dinosaur probably stepped into soft ground, which later filled with sand and mud that solidified. The softer rock around the impression eroded away, leaving the bulge. Photo credit: Mark Ryan/Flickr

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