Hesperosaurus

Hesperosaurus (from Ancient Greek ἕσπερος (hésperos), meaning "western", and σαῦρος (saûros), meaning "lizard") is a herbivorous stegosaurian dinosaur from the Kimmeridgian age of the Jurassic period, approximately 156 million years ago.

Fossils of Hesperosaurus have been found in the state of Wyoming and Montana in the United States of America since 1985. The type species Hesperosaurus mjosi was named in 2001. It is from an older part of the Morrison Formation, and so a little older than other Morrison stegosaurs. Several relatively complete skeletons of Hesperosaurus are known. One specimen preserves the first known impression of the horn sheath of a stegosaurian back plate.