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Stegosaurus (based on more traditional restorations)
Baby Stegosaurus

Stegosaurus (Steg-oh-sore-us), Roofed Lizard lived in the Late Jurassic of North America. It is the most common ornithscian from the Morrison Formation.

Content List

1. Genera & species

2. Characteristics

a. Size

b. Behavior

3. History of Discovery

4. Paleoenvironment

5. References

Genera and Species

Classification: Thyreophora, Stegosauridae.

Species: S. armatus, S. longispinus, S. homheni, S. mjosi, S. stenops, S. discurus, S.madagascariensis, S. seeleyanus, S. ungulatus

Senior synonym: S. sulcatus, S. duplex, Hypsirophus ungulatus


The rear legs of Stegosaurus were much longer than the front so the animal sloped down to a small head. The 2 m (6 ft) long tail was held up horizontal to the ground and could be swung upwards and sideways. The arrangement of the armor plates along the back and tail has been in dispute for decades. The plates alternated from side to side and were not in a single line. The largest of these pointed plates were 76 cm/2 ft high and 79 cm long. There were 2 pairs of spikes on the end of the tail, and these are actually on the sides pointing outwards, rather than standing straight up as previously thought. Additional armor in the form of rounded, flat bones covered the hips and the throat, and possibly the remainder of the body and tail as well. As with other ornithischians, Stegosaurus has a horny, toothless beak. A pad of spongy tissue beneath the feet helped to support the 2 ton weight. The rear feet had 4 toes, 5 at front, all had hooves. The brain was very small, and a large nerve centre in the hips may have helped to control the legs and tail.


Length 9 m (30 ft).

Weight 1.8 - 4 tons.


Stegosaurus was a low to medium browser. It may have preferred the better watered portions of the Morrison. The plates on back were probably used for display and species recognition rather than heat exchange or defense.

History of Discovery

Discovered by Marsh in 1877 and known from Skulls, skeletons, hundreds of skeletal remains. Most have been mature individuals, but in recent years juvenile Stegosaurus skeletons have been discovered.


Found in North America (Utah and Colorado USA) in semi arid plains with forested rivers with a short rainy season.


1. Paul, G. (2010). The Princeton Field Guide to Dinosaurs (pp. 5317). Princeton, New Jersey: University Press Princeton.

2. Worth, G. (1999). The Dinosaur Encyclopaedia (pp. 2089). Scarborough, Western Australia: HyperWorks Reference Software.