The Stegosaurus genus is a member of the Stegosauridae family, which belongs to the Thyreophora infraorder. Stegosaurus fossils have been unearthed in North America, specifically in the Morrison Formation, an ancient geological deposit that spans across several western U.S. states. It lived during the late Jurassic period.

Stegosaurus is immediately recognizable by its unique combination of features. It had a relatively small head perched atop a large, sturdy body. One of its most remarkable features is the array of large, bony plates that run along its back in a double row. These plates, believed to serve various functions including thermoregulation and display, contribute to the dinosaur's iconic appearance. An average stegosaurus measured around 30 feet in length, stood between 9 and 13 feet tall, weighed approximately 5.5 tons (equivalent to 11,000 pounds), and possessed a remarkably diminutive brain size, akin to that of a walnut.

Perhaps even more famous is the spiked tail, or "thagomizer," which bears four pairs of sharp, pointed spikes. These spikes were formidable defensive tools against predators, and their orientation suggests a wide range of motion, potentially used as a deterrent or weapon.

Stegosaurus is most notably distinguished by its distinctive dermal plates, comprising an array of 17 to 22 distinct plates and flat spines. These structures were specialized osteoderms, akin to those observed in present-day crocodiles and numerous lizards. Unlike being directly connected to the skeleton, they emerged from the skin. The largest plates were situated atop the hips, with dimensions exceeding 60 cm (24 in) in width and 60 cm (24 in) in height. These bony plates along Stegosaurus' back are subjects of ongoing speculation. It is believed that these plates played a role in temperature regulation, similar to how some modern reptiles use basking to warm up. Additionally, these plates may have been brightly colored and used for communication or mating displays, enhancing the social dynamics of the species.

The spiked tail, while often thought of as a weapon, was likely employed more as a means of defense. Stegosaurus may have swung its tail to deter predators or rival individuals. This unique defense mechanism further illustrates the complex interactions within prehistoric ecosystems.