Thespesius

Thespesius, or Thespecius, is an extinct hadrosaur described by Joseph Leidy in 1876.
History of "Thespesius".
"Thespecius" was discovered in Montana in 1855. Known fossils include vertebrae and toe bones (phalanx). 
The name "Thespesius" means wondrous one. Leidy avoided using the suffix "saurus" in the genus name because Vandiveer Hayden had claimed the bones came from a layer from the Miocene so there was a chance that the animal would turn out to be a mammal, though Leidy himself was convinced it was a dinosaurian. "Thespesius" turned out to be a dinosaur. The specific name "occidentalis" means "western" in Latin.