Hesperosaurus

Hesperosaurus (meaning "western lizard", from Classical Greek, ἕσπερο-/hespero- "western" and σαυρος/sauros "lizard") was a herbivorous dinosaur from the Kimmeridgian to Tithonian epochs of the Jurassic period (approximately 150 million years ago), whose fossils are found in the state of Wyoming in the United States of America. It is from an older part of the Morrison Formation, and so a little older than other Morrison Stegosaurs.

Discovery and Species
It was described in 2001 by Kenneth Carpenter and colleagues, who took the name for its location in the western United States. A nearly complete skull and much of the skeleton was found. The only species known is Hesperosaurus mjosi. It is present in stratigraphic zone 1 of the Morrison Formation.[1]

Susannah Maidment and colleagues proposed in 2008 that Hesperosaurus should be considered a synonym of Stegosaurus, with H. mjosi becoming Stegosaurus mjosi.