Where Dinosaurs Roamed: Lost Worlds of Utah's Grand Staircase

by Christa Sadler

Southern Utah’s Grand Staircase region is one of the best places in the world to study the period near the end of the Age of Dinosaurs—a time called the Late Cretaceous. In a relatively short period (geologically speaking!) of about 25 million years, southern Utah was at times covered with an ocean teeming with life, swampy shorelines, and massive rivers draining a huge mountain range in the west. The diversity of plant and animal life was astonishing, and the incredible fossil discoveries in these Late Cretaceous rocks have become a critical piece in a puzzle that stretches from Alaska to Mexico.

The Late Cretaceous was an important era in the history of life. Modern mammals, birds, and flowering plants were just getting their start, slowly gaining ground in the ecosystems of the time. Many of the fossils that paleontologists have found in southern Utah are unique: big, headline-grabbing creatures such as a dinosaur with fifteen horns; a distinctive cousin of Tyrannosaurus rex; a peculiar scissor-clawed dinosaur with feathers; and a thirty foot-long alligator relative. Add to this a host of smaller vertebrates, invertebrates, and plants, and paleontologists have been able to recreate entire ecosystems from the time between 74 and 100 million years ago.
Altogether, these finds paint a picture of life in a very hot world, meaning the creatures and ecosystems of southern Utah near the end of the Age of Dinosaurs may have lessons to teach us about our future world as well.