Mesozoic Era Late Jurassic Period Dinosaurs Stegosaurus


Quick Facts
Name Meaning:Roof Lizard
Distribution:Colorado, Utah, Wyoming, USA; Europe
Time Period:Late Jurassic, 150 Ma
Length:30 ft. (9 m)
Height:9 ft (2.75 m)
Weight:2 tons
Habitat:Woodlands or Plains

Linnaean Classification
Cladistic Classification
  • Dinosauria
    • Ornithischia
      • Genasauria
        • Thyreophora
          • Eurypoda
            • Stegosauria
              • Stegosauridae
                • Stegosaurinae
                  • Stegosaurus


The Stegosaurus was first discovered in Colorado and named by Othniel Charles Marsh in 1877. Marsh originally thought that the plates discovered with the dinosaur had been lain flat across the dinosaurs back, hence the name. This theory was later discarded. He also thought that the Stegosaurus was bipedal, though he changed his mind in 1891 in favor of being quadrupedal due to the animals size and weight. So far only two well known species have been discovered with a third lesser-known species. Although originally discovered only in Western North America, recent discoveries have been made in Portugal, proving that the Stegosaurus had a wide range including Europe as well. The Stegosaurus is of the most popular dinosaurs in modern culture. It has been depicted in children's toys, media, and film, including King Kong (1933) and Steven Spielberg's The Lost World.


Stegosaurus plate
Stegosaurus plate.
The Stegosaurus was a large, heavily built dinosaur that roamed the Late Jurassic on four legs. It had a posture different than most dinosaurs with its rounded back, and low head position. It had large bony plates along its spine, extending from the head to the tail. These spikes were not connected to the bone of the spine but were attached to the skin. At the end of its tail it bore two sets of lethal spikes. It was the size of a rhinoceros, and as long as a bus. This makes it the largest known plated dinosaur. Its head was held low and its mouth was a narrow toothless beak. The teeth were farther back in the cheeks. It is somewhat unknown whether the Stegosaurus held its tail high or low to the ground, although evidence strongly suggests that it was held high. Its hind feet had only three toes while the front feet had five. Its skull was very small in proportion and carried a braincase, that may have been the smallest braincase of any known dinosaur, no bigger than a dogs.


The Stegosaurus probably lived in the woods or plains feeding on low vegetation. It is possible that the Stegosaurus could have reached high plants by rearing on its hind legs. The tail would have been able to handle the stress this would have put on it because it was more flexible than the tails of most dinosaurs. Its narrow snout made it a selective eater and probably fed on soft shrubs. The use of the back plates is in some doubt. Although it may have been used as a defense by flapping them to one side or the other, this would not have provided much protection from a predator like the Allosaurus. The plates may have been used for thermal regulation by exposing sunlight to the blood vessels contained in the plates. It is likely that the plates were used as a display or a warning by flushing blood into them. The spikes on the tail were almost certainly used for defense especially considering the flexible nature of the tail. Also, an Allosaurus was uncovered with what appeared to be a puncture wound the size of a Stegosaurus spike. Due to discovered dinosaur tracks it is very likely that the Stegosaurus traveled in herds.

ScienceViews Writer: Jason Hamilton.

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