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Stegosaurus

Stegosaurus is a genus of armored, herbivorous dinosaur from the Late Jurassic period.

By Ethan Anderson| Reviewed by Olivia Bennett, Standards & Fact-Checking Lead| Updated July 26, 2026|2 min read| Fact-checked

Stegosaurus is a genus of armored, herbivorous dinosaur from the Late Jurassic period. It is best known for the large bony plates along its back and the spikes on its tail. Stegosaurus is one of the most recognizable dinosaurs and a classic example of Jurassic life.

Description

Stegosaurus was a large, armored dinosaur with a distinctive silhouette. It had a row of broad, bony plates along its back and a tail equipped with spikes. Its body plan and unusual features make it one of the best-known prehistoric animals.

Diet and behaviour

Stegosaurus was herbivorous and likely fed on low-growing plants such as ferns and cycads. Its tail spikes are widely interpreted as a defensive weapon against predators, and it was a quadrupedal animal.

Discovery and classification

Stegosaurus was first named in the 19th century and is the best-known member of the stegosaur family. It belongs to the armored ornithischian dinosaurs. The name Stegosaurus means "roof lizard" or "roofed lizard," referring to its back plates.

Fossil record

Stegosaurus fossils have been found mainly in North America, especially in the western United States in rocks of the Morrison Formation. These fossils help reconstruct Late Jurassic ecosystems and are particularly associated with Colorado, Utah, and Wyoming.

Key facts

  • Stegosaurus is one of the most recognizable dinosaurs because of its large back plates and tail spikes.
  • It was a quadrupedal herbivore that ate plants.
  • It lived during the Late Jurassic period, roughly 152–145 million years ago.
  • Fossils are especially associated with the western United States, including Colorado, Utah, and Wyoming.
  • Its brain was very small relative to its body size.
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Canadian context

Stegosaurus is a major dinosaur for Canadian readers because it is a classic museum and textbook example of Jurassic life and armored dinosaur anatomy. Canadian museums and science education materials often use Stegosaurus to teach about dinosaur classification and adaptation.

Frequently asked questions

What does Stegosaurus mean?
It means "roof lizard" or "roofed lizard," referring to its back plates.
What did Stegosaurus eat?
Stegosaurus was an herbivore and likely ate low-growing plants such as ferns and cycads.
How did Stegosaurus defend itself?
Its tail spikes were probably used for defense against predators.
How big was Stegosaurus?
Estimates vary, but many sources place it at about 6.5–9 metres long.
When did Stegosaurus live?
It lived in the Late Jurassic, about 152–145 million years ago.
Where have Stegosaurus fossils been found?
They are mainly known from western North America, especially the United States.

References

  1. Natural History Museum — https://www.nhm.ac.uk/discover/dino-directory/stegosaurus.html
    Supports: Name meaning, diet, time period, length, and general description.
  2. Encyclopaedia Britannica — https://www.britannica.com/animal/Stegosaurus
    Supports: Genus status, Late Jurassic age, size range, and distinguishing plates/spikes.
  3. National Geographic Kids — https://kids.nationalgeographic.com/animals/prehistoric/facts/stegosaurus
    Supports: Back plates, tail defense, approximate age, fossil regions, and small brain.
  4. Live Science — https://www.livescience.com/24184-stegosaurus-facts.html
    Supports: Late Jurassic range, western North American distribution, plates, size, and herbivory.
  5. National Park Service — https://www.nps.gov/places/stegosaurus-ungulates.htm
    Supports: Plant-eating dinosaur, Late Jurassic North American occurrence, and name meaning.