Chaoyangsaurus

Chaoyangsaurus ("Chaoyang lizard") was a marginocephalian dinosaur from the Late Jurassic of China (dated to between 150.8 and 145.5 million years ago).[1] Chaoyangsaurus belonged to the Ceratopsia (Greek for "horned faces"), a group of primarily herbivorous dinosaurs with parrot-like beaks which thrived in North America and Asia during the Cretaceous Period (which ended 66 million years ago). Chaoyangsaurus, like all ceratopsians, was primarily a herbivore.

Discovery and species
Chaoyangsaurus was found in the Chaoyang area of Liaoning Province in northeastern China. The specific name honours the Chinese paleontologist C. C. Young.

Chaoyangsaurus species
 * C. youngi (type)

Spelling
Unlike many other dinosaurs, Chaoyangsaurus had been discussed in a number of sources before its official publication. As a result of this, several different spellings of its name have come and gone as nomina nuda ("naked names", names with no formal description behind them). The first name to see print was Chaoyoungosaurus, which appeared in the guidebook to a Japanese museum exhibit, and was the result of an incorrect transliteration.[2] Zhao (1983) also used this spelling when he first discussed the species, so it is technically a nomen nudum. Two years later, Zhao again used this early spelling when he assigned a type specimen and species name, Chaoyoungosaurus liaosiensis (Zhao, 1985).

According to Dong (1992), the name Chaoyoungosaurus had been officially described in a paper by Zhao and Cheng in 1983, but no cite for this supposed paper exists, and it is likely it was not properly published. Dong, in his 1992 paper on the subject, also emended the name to the "correct" spelling of Chaoyangosaurus (note the extra letter "o"). However, since this renaming was not accompanied by a formal description of the dinosaur, Chaoyangosaurus must also be considered a nomen nudum.

It was not until 1999 that the dinosaur finally received an official name. Sereno (1999) used the name Chaoyangsaurus in an overview of ceratopsian taxonomy. Once again, that name was a nomen nudum. However, in December of that year, Cheng, Zhao, and Xu published an official description using the name Chaoyangsaurus youngi, and as the first name for this genus that is not a nomen nudum, it has official priority over all other spellings that have been used.