Chaoyangsauridae

Chaoyangsauridae is a family of ceratopsian dinosaurs. They are among the earliest known marginocephalian dinosaurs, with remains dating to about 160 million years ago, during the Late Jurassic period. Members of this group had sharp beaks for snipping off leaves to eat, and a very small frill.

Quick Facts Scientific classification, Type species ...

Chaoyangsauridae Temporal range: Late Jurassic, 160–148 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Compared close-up of the four so far known chaoyangsaurid genera, with pink representing known parts of skulls
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	†Ornithischia
Clade:	†Ceratopsia
Family:	†Chaoyangsauridae Zhao, Cheng, & Xu, 1999
Type species
†Chaoyangsaurus youngi Zhao, Cheng, & Xu, 1999
Genera
†Chaoyangsaurus †Hualianceratops †Stenopelix? †Xuanhuaceratops †Yinlong

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This family is officially defined in the PhyloCode as "the largest clade containing Chaoyangosaurus youngi, but not Psittacosaurus mongoliensis and Triceratops horridus".^[1]

Four dinosaur genera, Chaoyangsaurus, Xuanhuaceratops, Yinlong and Hualianceratops, are usually considered to belong to the Chaoyangsauridae.^[2][3][4] In 2020, Yu et al. classified Stenopelix as a chaoyangsaurid.^[5] All five animals are more primitive (or basal) than both Psittacosaurus and neoceratopsians.