Stegosaurus is immediately identifiable because of the double row of bony plates along its back and the spikes on its tail. Stegosaurus lived during the Jurassic Period. The first remains were discovered by Arthur Lakes near Morrison Colorado in North America in the Morrison Formation - famous for the wealth of dinosaur fossils discovered there. The fossils were shipped to O.C. Marsh at Yale's Peabody Museum of Natural History in New Haven, Connecticut, and figured prominently in the 19th century Bone Wars when paleontologists Edward Drinker Cope and Othniel Charles Marsh competed furiously to see who could find the most dinosaur remains.

The plates along its back may have served several purposes: as defense against predators, and as a way to regulate body temperature, similar to the large sail on the back of the dimetrodon. The spikes at the tip of its tail were probably for defense. The brain of the stegosaurus was about the size of a dog's, and was very small compared to the size of its body.


  • Estimated size: 9 meters (30 feet)
  • Estimated weight: 4 to 5 metric tons

Size compared to human

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