Stegosaurus
Stegosaurus stenops • "Roofed / Covered Lizard"
Stegosaurus was a plant-eating, armoured dinosaur from Late Jurassic North America. It had two rows of plates along its back and a spiked tail; scientists are still investigating the plates’ roles, while the tail spikes were likely defensive.
- Length
- ≈9 m
- Weight
- ≈5.0 t
- Diet
- Herbivore
- Danger
- ★★★★★
Overview
The iconic plated fortress of the Jurassic. Stegosaurus defended itself against ferocious predators like Allosaurus using its fearsome four-spiked tail (the "thagomizer"), which could swing with pinpoint accuracy to pierce predator bones.
“The tail spikes are formally called the "Thagomizer" in paleontology, a term coined by cartoonist Gary Larson in a 1982 Far Side comic that was subsequently adopted by scientists.”
Key facts
Strengths
- Lethal thagomizer tail strike with flexible horizontal whip arc
- Dorsal plates provide visual intimidation and thermal blood flushing
- Low center of gravity with armored throat protection against neck-biters
Weaknesses
- Small walnut-sized brain (low cognitive intelligence)
- Vulnerable flank and soft underbelly if out-maneuvered
- Low running sprint speed
Natural weapons
- Thagomizer: Four 1.0-meter pointed bony tail spikes
- 17-22 alternating upright vascular dorsal plates for intimidation and thermoregulation
- Heavily armored throat protected by dense osteoderm ossicles
Movies vs. science
Myth: Popular myth claimed Stegosaurus had a "second brain" in its hip.
Reality: The hip cavity held an enlarged glycogen body that stored energy, not a second thinking brain.
Size & simulator stats
Estimated at about 9 m long. Fossils preserve plates and tail spikes, but body-size estimates vary among specimens.
- Length
- 9 m
- Height
- 4 m
- Weight
- 5.0 t
Illustrative simulator values (not measured biology)
See how Stegosaurus measures up in the sourced size comparison chart.
Habitat
Semi-arid floodplain savannas and open conifer woodlands of Jurassic North America.
Western North America, especially the present-day United States.
Diet
Low browser eating ferns, horsetails, mosses, and cycads using a small beak and leaf-shaped cheek teeth.
Herbivore. Fossils and teeth indicate plant-eating; the precise plants it ate are not known.
Fossils & discovery
First described from United States & Portugal in 1877 (Morrison Formation (Colorado, Wyoming, Utah)).The tail spikes are formally called the "Thagomizer" in paleontology, a term coined by cartoonist Gary Larson in a 1982 Far Side comic that was subsequently adopted by scientists.
Research sources
Sources checked on by the Dinosaurs Names Editorial Team. Editorial policy
Gallery
Related dinosaurs
Battle Arena
Can anything beat Stegosaurus?
Send Stegosaurus into an illustrative matchup against any other species and compare attack, defense, and bite force.
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