One of the most popular dinosaurs of all time, the Stegosaurus is quite distinctive with its row of large bony plates along its back, and the four fearsome spikes on its tail. These spikes are believed to have been used to protect Stegosaurus from attacking Jurassic predators such as Allosaurus.
Stegosaurus was discovered and described in 1877 by OthnielCharles Marsh. Originally, its plates were thought to lay flat onthe dinosaur's back, like a turtle's shell. Later, more completefindings showed that they stood up vertically on Stegosaurus'sback, though their exact arrangement is still something of amystery. Though sometimes shown in a symmetrical double row, themost widely accepted current theory is that the plates werestaggered in two alternating rows.
The function of these plates is something of a mystery. It wasoriginally believed that Stegosaurus used them for defense, but dueto their somewhat thin and fragile nature, this is unlikely. Theymay have been used to help regulate body temperature, or fordisplay.
A recent, well-preserved Stegosaurus showed that these dinosaurshad additional bony protective armor on their chin and throat,called "gular armor". Tiny bony structures called "ossicles"protected the underside of the animal's neck, like chainmailarmor.