Approximately 110 million years ago, Utah and Colorado were a floodplain with damp and arid seasons. After heavy precipitation, the rivers would swell and burst water mixed with muddy sediment. Numerous different species of dinosaurs inhabited the floodplain. Fish, turtles, and crocodiles lived among them. The prehistoric organisms which once inhabited the region were discovered in the 1940s. As a result, Cedar Mountain Formation became one of the top North American areas to study dinosaurs from the Early Cretaceous.
A fraction of a backbone that could have been from a brachiosaurus was found in Cedar Mountain Formation.
Here are some of the dinosaurs that were excavated in Cedar Mountain Formation:
- Gastiona, who was a part of the anklyosaur (meaning armored dinosaur) family, probably ate ferns, and was covered in spines, the longest being at the shoulders. One bed of bones contains 3,000 bones from possibly 20 of these dinosaurs.
- Deinonychus, a carnivorous dinosaur who hunted in teams. They had sharp teeth designed to rip flesh.
- Tenontosaurus, a huge herbivorous dinosaur who walked on two legs but dropped on four when eating.
- Utahraptor, a dromaeosaur (meaning running lizard) who had long, narrow teeth and a curved claw on each foot that grew to be up to 15 inches or 38 centimeters. It was intelligent and hunted in teams that stalked their prey before attacking it by kicking and biting.
In approximately 20 million years, sediments from prehistoric rivers and pools of the Cretaceous collected and hardened into rocks. Today, these rocks create a formation of high cliffs made of pebbly sandstone the color of rust, mudstone, and siltstone. These different types of rocks faced erosion which turned them into the beautiful canyons, pinnacles, and arches we see today.
