Stegosaurus ungulates

Artwork depicting a stegosaurus dinosaur

NPS/Bob Walters Tess Kissinger

 
This Stegosaurus at the Carnegie Museum shows the plates staggered along the back, as most paleontologists believe they were arranged.
This Stegosaurus at the Carnegie Museum shows the plates staggered along the back, as most paleontologists believe they were arranged.

Stegosaurus is a plant eating dinosaur with plates on its back and spikes on its tail. Stegosaurus ungulatus is a species of ornithischian dinosaur from the Late Jurassic of North America, found in the Morrison Formation. Stegosaurus means “covered lizard,” a reference to its plates. The function of these plates has been disputed by paleontologists. Due to the vascular nature of the plates, their function as a thermal regulation mechanism has been suggested. The plates contained blood vessels that could possibly constrict or expand to regulate heat loss. Another theory is that they were used as a display to attract a mate, like colorful feathers on a bird or antlers on a deer. It could have been any or all of the three. Since the plates were not directly attached to the bones of the skeleton, they were easily separated from the body after death. Massive spikes on the end of its tail were used in defense against predators. At Dinosaur many isolated plates and spikes have been found throughout the Carnegie Quarry.

 
 

Stegosaurus is one of the most easily recognized dinosaurs of the Jurassic. The plates on its back and spikes on its tail make it one of the most unique creatures of the Mesozoic (Age of Dinosaurs). The Carnegie Quarry is so rich in fossils that multiple skeletons have been mounted from early excavations at Dinosaur.

 
This juvenile Stegosaurus femur (upper leg bone) is much smaller than that of an adult.
This juvenile Stegosaurus femur (upper leg bone) is much smaller than that of an adult.

In 1977 paleontologists at Dinosaur National Monument removed a juvenile Stegosaurus from the Carnegie Quarry face. They found limb bones, shoulder blades, most of the hips, some ribs, and skull fragments. Since plates were not found, it is unknown if juveniles had them at all. However, these fossils make up the most complete juvenile Stegosaurus ever found. A mounted cast of the fragile bones ison display at the Quarry Exhibit Hall.

 
 

Last updated: May 22, 2019

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