Bones from a Stegosaurus were found near Morrison in 1877 by Golden schoolteacher Arthur Lakes.
The dinosaur was named later that year by paleontologist Othniel Marsh, who initially believed that it was turtle-like and that its plates lay flat over its back, like a turtle’s shell. Later research concluded that the triangular plates stood vertically in two rows and ran down the back of the plant-eating dinosaur, which typically was 30 feet long and 14 feet high and weighed five tons.
The Stegosaurus also sported a spiked tail that some paleontologists believe was used as a defensive weapon. The tail was nicknamed the “thagomizer” by cartoonist Gary Larson in a 1982 “Far Side” comic strip, and the name was picked up by paleontologist Ken Carpenter of the Denver Museum of Nature & Science and eventually by other scientists, the Smithsonian Institution and Dinosaur National Park.
The Stegosaurus, which dates back to the Jurassic era, was declared Colorado’s official State Fossil in 1982 by Gov. Richard Lamm at the urging of a fourth-grade class from Thornton’s McElwain Elementary School.