INFO |
Zhao Xijin, Cheng Zhengwu & Xu Xing, 1999. "The earliest
ceratopsian from the Tuchengzi Formation of Liaoning, China,"
Journal of Vertebrate Paleontology 19(4): 681-691 [December 13,
1999].A primitive ceratopian from China that may be basal to both
psittacosaurs and neoceratopians.
Holotype IVPP V11527 consists of a partial skull with
lower jaws, several cervical vertebrae and a partial scapula and
humerus. The name of this genus was first published in Japanese in a
dinosaur chart in an anonymous guidebook to a Chinese dinosaur
exhibition in Japan in 1981 or 1982. The spelling
Chaoyoungosaurus from that article is a transliteration
provided by M. Tanimoto (pers. comm.); coincidentally, this was also
its first published Latin spelling, as a nomen nudum in Zhao, 1983.
The type species name, Chaoyoungosaurus liaosiensis, was
subsequently published, also as a nomen nudum, by Zhao in
1985.
Dong (1992) asserted that this dinosaur had been described
and named in 1983 by Zhao & Cheng, but the citation for this
reference is missing from Dong's bibliography. Dong also emended the
spelling of the genus to Chaoyangosaurus. P. Sereno (pers.
comm.) noted that the 1983 paper by Zhao & Cheng with the
spelling Chaoyangosaurus was almost certainly not properly
published and that spelling is also a nomen nudum.
Regardless of these earlier spellings, the generic name
finally became Chaoyangsaurus, with type species named
Chaoyangsaurus youngi, when the dinosaur was formally
described by Zhao, Cheng & Xu in the December 13, 1999 issue of
the Journal of Vertebrate Paleontology. This is the spelling
previously used by Sereno in his June 25, 1999 article in Science on
dinosaur phylogeny.
The new ceratopsian specimen, Chaoyangsaurus youngi
gen. et sp. nov., was collected from the Tuchengzi Formation (Middle
or Late Jurassic) of Liaoning, China. Distinctive characteristics of
the new species include quadratojugal overlapping posterior side of
quadrate shaft; lack of a broad lateral surface of the quadrate
shaft; convex posterior margin of the ventral portion of the
quadrate; a ridge between the planar lateral and Ventral surface of
the angular. The discovery of Chaoyangsaurus youngi extends
the record of ceratopsian from back in time from the Early
Cretaceous into the Middle or Late Jurassic. Some characters of
C. youngi may suggest a close relationship between Ceratopsia
and Heterodontosauridae. |