Chaoyangsaurus

*Chaoyangsaurus youngi*

***Chaoyangsaurus*** ("Chaoyang lizard") was a marginocephalian dinosaur from the Late Jurassic of China (dated to between 150.8 and 145.5 million years ago). *Chaoyangsaurus* belonged to the Ceratopsia (Greek for "horned faces"), *Chaoyangsaurus*, like all ceratopsians, was primarily a herbivore.

## Discovery

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

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. 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.

## JPInstitute.com Description

Chaoyangsaurus is a very important member of the family of horned dinosaurs because it shows they lived during the Jurassic period. Before the discovery of this little dinosaur, it was believed that the horned dinosaurs, which include Triceratops, first showed up in the Cretaceous period. This early family member lived before Protoceratops and Psittacosaurus, which are considered some of the earliest members of this family. Like the other early family members, Chaoyangsaurus is also from Asia.

First discovered in the early 1980's, rumors of this dinosaur floated around the paleontological community until it was formally described in 1999. It had previously been known by a somewhat different spelling, Chaoyoungosaurus, but its formal description changed that. This dinosaur seems to show an evolutionary link between the ceratopsian dinosaurs and the heterodontosauridae.

## Links

http://web.archive.org/web/20030803053606/http://www.jpinstitute.com/dinopedia/dinocards/dc\_chaoy.html

## References

1. ↑ Holtz, Thomas R. Jr. (2011) *Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages,* Winter 2010 Appendix.