Hesperosaurus, scientifically known as "Hesperosaurus mjosi," is classified as a member of the Stegosauria group, specifically belonging to the Stegosauridae family. The name "Hesperosaurus" is derived from the Greek word "hesperos," meaning "western," in reference to its discovery in western North America. It lived during the Late Jurassic period, approximately 156 to 152 million years ago.

Hesperosaurus was first discovered in 1985 in the Morrison Formation of Wyoming, USA, by paleontologist Kenneth Carpenter, and its fossils have provided valuable insights into the stegosaur dinosaurs of this region.

Hesperosaurus was a medium-sized dinosaur, estimated to have measured around 21 feet (6.5 meters) in length. As a stegosaur, it possessed a unique array of distinctive plates and spikes on its back and tail. It is estimated to have weighed 5 tons.

The plates of Hesperosaurus were broad and triangular, arranged in two rows along its back. Additionally, it sported pairs of sharp spikes on its tail, known as thagomizers, which served as a potential defense against predators.

The combination of its plates and spikes made Hesperosaurus an imposing and easily recognizable dinosaur of its time.

Stegosaurs, including Hesperosaurus, were known for their relatively small brains and likely had simple social structures. They may have lived in family groups or small herds, finding safety in numbers and potentially engaging in simple social interactions.

The plates of Hesperosaurus might have played a role in regulating its body temperature. These plates had an extensive network of blood vessels, suggesting they could have functioned as heat exchangers, absorbing or releasing heat as needed to regulate body temperature.

The thagomizer on its tail, though impressive, was likely used mainly as a defensive weapon against predators rather than a means of attack. The tail spikes would have made Hesperosaurus a formidable opponent when confronted by carnivorous dinosaurs of its time.