Museum Frankfurt


Stegosaurus stenops

Order: Ornithischia
Suborder: Thyreophora
Infraorder: Stegosauria
Diet: plants
Weight: approx. 2-3 tons
Length: approx. 6 metres
Age: 155-145 million years (Upper Jurassic)
Fossil site: “Bone Cabin Quarry” Wyoming (USA)
at Senckenberg:

(Original at American Museum of Natural History, New York/USA)

Characteristic of Stegosaurus, also called the "spiketail", were the upright vertical bony plates along the back. The largest plates were 60 cm tall. They stood in two rows in an alternating sequence and became ever smaller towards the head and tip of the tail. The bony plates probably served to protect the spine. It is also surmised that they had a good blood supply and could thus be used to regulate body temperature. As a matter of fact, the bony plates show impressions of the former blood vessels. This could also have served to deliver the blood supply
to the horny layer which covered the plates.

At the tip of the tail, there were two pairs of powerful bony spikes, which could be up to one meter long. Undoubtedly, they were also coated with a layer of horn and thus prolonged the dinosaur's lifetime a little. Stegosaurus could use these dangerous weapons to defend itself. The enlarged diameter of the spinal canal in the vertebrae of the pelvic region, was for a long time interpreted as the location of a second brain. Other researchers assume, rather, that this was the location of a large reflex center of the spinal cord, that could control the tail. Still others suggest that these so-called cavities were the location of a glycogen gland, which, in case of danger, released energy in the form of sugar, so the huge animal could react quickly with his defense weapons.

Compared with the massive body, the head of the Stegosaurus was surprisingly small. Its brain was only about as big as a walnut. At the top of its mouth it had a beak with horny edges and small teeth in the back part of the jaw. The dentition of Stegosaurus was not well suited for chewing plant foods. It possibly swallowed stones to crush the tough plant food, which worked like millstones in its stomach.

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