Stegosaurus

Stegosaurus is one of the most recognizable dinosaurs ever. It had two rows of large bony plates along its back. It also had a dangerous spiked tail. Stegosaurus lived about 155 million years ago during the Jurassic Period.

Plates and Spikes

Stegosaurus had 17 bony plates along its back. These plates may have helped it control its body temperature. Its tail had four sharp spikes, each about 2 to 3 feet long. Scientists call this spiked tail a "thagomizer." It could swing its tail to fight off predators.

A Gentle Giant

Stegosaurus was about 30 feet long and 14 feet tall. It weighed about 5 tons. Despite its big body, its brain was only the size of a walnut! It ate low-growing plants because its head was close to the ground. It could not reach leaves in tall trees.

Fun Facts

• The word "thagomizer" for Stegosaurus's tail spikes was invented by a cartoonist, not a scientist.
• Stegosaurus lived 80 million years before T. Rex — it is closer in time to us than to T. Rex!
• Its back plates were covered in skin and may have blushed red with blood.

Did You Know?

Stegosaurus is the state dinosaur of Colorado. The first Stegosaurus fossil was found near Morrison, Colorado in 1877!