75 million years ago, during the Cretaceous Period, the state of Utah was part of a land mass called Laramidia. The desert we see today was probably like a swamp back then. There were plenty of ferns, trees, and flowers, but no grass. It was also full of dinosaurs, reptiles, and even some mammals!
Because of their size, the largest herbivores were mostly safe from predators like Teratophoneus (TER-uh-TOO-foh-NEUS). Instead, these predators likely ate smaller dinosaurs that were easier to take down.
The rich plant life was great for giant herbivores like the sauropod Alamosaurus (AL-uh-MO-SAR-us) or the ceratopsian Nasutoceratops (NAY-soot-OH-SER-uh-tops). These animals spent almost of their time grazing on plants to get enough energy for their big bodies.
There were a couple of animals that might look familiar today, including the relative to the modern alligator, Deinosuchus (DAY-no-SOOK-us).