Stegosaurus

Stegosaurus (meaning "roof-lizard") was a type of plant-eating dinosaur which lived in what is now western North America.

Stegosaurus lived in the Late Jurassic period around 155 to 145 million years ago. It is among the most easily recognized dinosaurs, due to the distinctive double row of kite-shaped plates on its back and the long spikes on its tail. The armor was necessary as it lived with such meat-eaters as Allosaurus and Ceratosaurus.

Discovery and species
Stegosaurus was originally named by Othniel Charles Marsh in 1877, from fossils found near Morrison, Colorado. These first bones became the first species of Stegosaur named: Stegosaurus armatus.

Several different Stegosaurus species have been found.
 * Stegosaurus armatus: This was the first type of Stegosaurus to be found. Over thirty different skeletons have been discovered by scientists. This type had four tail spikes and small plates. At 9 meters (30 ft), it was the longest species of Stegosaurus.
 * Stegosaurus stenops: Named by Marsh in 1887, it was discovered near Cañon City, Colorado, in 1886. This is the best known species of Stegosaurus, mainly because its fossils make at least one complete skeleton. It had large, broad plates and four tail spikes. S. stenops is known from at least 50 partial skeletons of both adults and juveniles, one complete skull and four partial skulls. It was shorter than S. armatus, at 7 m (23 ft).
 * Stegosaurus longispinus: This type of Stegosaur is known from one incomplete skeleton. S. longispinus had a set of very long tail spines. Like S. stenops, it grew to 7 m (23 ft) in length.
 * S. ungulatus: Named by Marsh in 1879 from remains recovered at Como Bluff, Wyoming, it is only known from a few backbones and armor plates. It is probably the same as S. armatus.
 * S. sulcatus: This is another partial skeleton. It is probably the same as S. armatus.
 * S. duplex: This animal is probably the same as S. armatus. It was also named by Marsh in 1887, . Its fossils were found in 1879 by Edward Ashley at Como Bluff, Wyoming.
 * ?S. seeleyanus: Probably the same as S. armatus.
 * ?S. (Diracodon) laticeps: Named by Marsh in 1881 from some jawbone fragments.