Chaoyangsaurus Zhao, Zheng & Xu, 1999
a.k.a Chaoyangosaurus
Chaoyangsaurus Zhao, Cheng & Xu, 1999
(J. Vertebr. Paleontol., 19 (4), 13 December: 681.
NcZ) "Chaoyang lizard"
chow-yahng-SAWR-us (Chaoyang + Gr. sauros "lizard") (m)
named to indicate a primitive ceratopsian dinosaur found in the Chaoyang area
of Liaoning Province, northeastern China; known from an incomplete skeleton including
the dorsal part of a skull, a mandible, an axis vertebra along with 6 cervicals,
and a fragmentary humerus and scapula (Holotype: IGCAGS V371 (Institute of Geology,
Chinese Academy of Geological Science (Beijing)). Chaoyangsaurus comes from
the Tuchengzi Formation (Ershijiazi locality) and dates either from the Middle or
the Late Jurassic, making it the earliest known ceratopsian--it is a small,
likely bipedal animal probably between 1.5 and 2 meters (5-7 ft) in total length
(the body proportions and tail size are not known). The skull is about 14 cm (5.5 in)
long from the tip of the rostral bone to the end of the quadrate, and triangular in form,
very broad at the back tapering to a narrow beaklike snout. The jugals flare well beyond
the skull roof as in other ceratopsians, but there is no preserved evidence of any features
resembling a frill or horns. The 8-9 maxillary teeth in each jaw are chisel-shaped with
denticles on the crowns and a central ridge; the 2 premaxillary teeth in each jaw are simple
and somewhat blade-like, with compressed crowns without denticles. The 11 dentary teeth
in each mandible are generally smaller than the maxillary teeth, with centrally directed
denticles on the crowns--the tooth rows of the lower jaw are positioned inside
the upper tooth rows when the jaws are closed. Chaoyangsaurus possesses a combination
of psittacosaurid and neoceratopsian features; some features suggest a relationship between
heterodontosaurs and ceratopsians. NOTE: The discovery was mentioned in literature dating back
to 1983 under the name "Chaoyangosaurus liaosiensis", but no diagnostic description was
published and the older name is invalid. The name also appeared in the form "Chaoyoungosaurus."
Type Species: Chaoyangsaurus youngi [YUHNG-ie] Zhao, Cheng & Xu, 1999: for Chung Chien Young
[Yang Zhongqian] (1897-1979), "in memory of the founder of vertebrae paleontology in China."
Ceratopsia ?Late Jurassic China [added 2/2000]
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