During the early days of the Jurassic Period, about 200 million years ago, a small dinosaur named Scutellosaurus lawleri roamed the floodplains and forests of what would much later become the Colorado Plateau.
This plant eater was among the earliest of all ornithischian dinosaurs, a branch that went extinct millions of years ago. It may have been the victim of larger predators and a changing climate. Members of the separate saurischian branch survived to become the birds of today.
The holotype of Scutellosaurus—the specimen that led to its scientific description—was discovered in 1971 in northeast Arizona by David Lawler. Museum of Northern Arizona paleontologist Edwin Colbert described the creature in 1981, and his wife Margaret Colbert illustrated it. Many additional partial specimens have since been collected from the same part of Arizona, giving us a composite picture of a more complete dinosaur.
Scutellosaurus moved gracefully on two hind legs, growing up to 4 feet long and tipping the scales at 22 pounds. The name means “little-shielded lizard”—for heavy body armor consisting of hundreds of hard, boney plates, or osteoderms, arranged in parallel rows from the neck to the end of the distinctively long tail.
This dinosaur must have been common, partly explaining the considerable number of individuals found in a small area.