Psittacosaurus

Psittacosaurus Temporal range: Early Cretaceous, 125–105 Ma PreꞒ Ꞓ O S D C P T J K Pg N
P. meileyingensis cast, Children's Museum of Indianapolis
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	†Ornithischia
Clade:	†Neornithischia
Clade:	†Marginocephalia
Clade:	†Ceratopsia
Family:	†Psittacosauridae Osborn, 1923
Genus:	†Psittacosaurus Osborn, 1923
Type species
†Psittacosaurus mongoliensis Osborn, 1923
Other species
List of other species †P. sinensis Young, 1958 †P. meileyingensis Sereno et al., 1988 †P. xinjiangensis Sereno & Zhao, 1988 †?P. sattayaraki Buffetaut & Suteethorn, 1992 †P. neimongoliensis Russell & Zhao, 1996 †P. ordosensis Russell & Zhao, 1996 †P. mazongshanensis Xu, 1997 †P. sibiricus Leshchinskiy et al., 2000 †P. lujiatunensis Zhou et al., 2006 †P. gobiensis Sereno, Zhao & Tan, 2010 †P. amitabha Napoli et al., 2019
Synonyms
Protiguanodon Osborn, 1923 Hongshanosaurus You, Xu, & Wang, 2003

Psittacosaurus (/ˌsɪtəkəˈsɔːrəs/ SIT-ə-kə-SOR-əs; "parrot lizard")^[1] is a genus of extinct ceratopsian dinosaur from the Early Cretaceous of what is now Asia, existing between 125 and 105 million years ago. It is notable for being the most species-rich non-avian dinosaur genus. Up to 12 species are known, from across China, Mongolia, Russia, and Thailand. The species of Psittacosaurus were obligate bipeds at adulthood, with a high skull and a robust beak. One individual was found preserved with long filaments on the tail, similar to those of Tianyulong. Psittacosaurus probably had complex behaviours, based on the proportions and relative size of the brain. It may have been active for short periods of time during the day and night, and had well-developed senses of smell and vision.

Psittacosaurus was one of the earliest ceratopsians, but closer to Triceratops than Yinlong. Once in its own family, Psittacosauridae, with other genera like Hongshanosaurus, it is now considered to be senior synonym of the latter and an early offshoot of the branch that led to more derived forms. The genera closely related to Psittacosaurus are all from Asia, with the exception of Aquilops, from North America. The first species was either P. lujiatunensis or closely related, and it may have given rise to later forms of Psittacosaurus.

Psittacosaurus is one of the most completely known dinosaur genera. Fossils of hundreds of individuals have been collected so far, including many complete skeletons. Most age classes are represented, from hatchling through to adult, which has allowed several detailed studies of Psittacosaurus growth rates and reproductive biology. The abundance of this dinosaur in the fossil record has led to the labelling of Lower Cretaceous sediments of east Asia the Psittacosaurus biochron.