''Changchunsaurus'' (meaning " Changchun lizard") is an extinct

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of small

herbivorous A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals typically have mouthpar ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

from Early Cretaceous deposits of

Gongzhuling Gongzhuling () is a county-level city under the administration of Changchun. It is located in central Jilin province of Northeast China, halfway between Siping and Changchun, along the main railway line in the Northeast. Major employers in the ci ...

Jilin Jilin (; alternately romanized as Kirin or Chilin) is one of the three provinces of Northeast China. Its capital and largest city is Changchun. Jilin borders North Korea ( Rasŏn, North Hamgyong, Ryanggang and Chagang) and Russia (Prim ...

, China. It is the first named dinosaur genus from Jilin.

Description

''Changchunsaurus'' was first named by Zan Shu-Qin, Chen Jun, Jin Li-Yong and Li Tao in 2005. The type and only known

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

is ''C. parvus'' ("parvus" meaning "petite"), named for its small size. It is known from a skull and skeleton and additional skull fragments. All specimens of ''Changchunsaurus'' were collected from the

Quantou Formation The Quantou Formation is a Cretaceous Period (Mesozoic Era) geologic formation in China. It is primarily Albian in age. It has been explored for its potential as a tight oil reservoir. Dinosaur remains are among the fossils that have been recover ...

of the Songliao Basin, dating to the Aptian– Cenomanian stages. ''Changchunsaurus'' is based on the

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of sever ...

JLUM L0403-j–Zn2, a skeleton and

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, th ...

, with a

premaxilla The premaxilla (or praemaxilla) is one of a pair of small cranial bones at the very tip of the upper jaw of many animals, usually, but not always, bearing teeth. In humans, they are fused with the maxilla. The "premaxilla" of therian mammal has ...

(upper beak) and partial

lower jaw In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

also known. Only the skull was figured and described in the official description. According to Zan ''et al.'' 2005, who described it, the animal shows a combination of features like those of derived ornithopods (reduction in size or loss of some skull fenestrae or holes), and features like those of more basal ornithopods (for example, five teeth in each premaxilla, short toothless portion of upper beak, and a small gap between beak teeth and cheek teeth). There is a projection that sticks out from the side of the

jugal The jugal is a skull bone found in most reptiles, amphibians and birds. In mammals, the jugal is often called the malar or zygomatic. It is connected to the quadratojugal and maxilla, as well as other bones, which may vary by species. Anatomy ...

or cheekbone, with what is described as a "nubble structure". The type individual was a small animal, around 1 meter long (3.3 feet, with a skull 11.5 centimeters long (4.5 inches). It was originally classified as a basal ornithopod,

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

unknown Unknown or The Unknown may refer to: Film * ''The Unknown'' (1915 comedy film), a silent boxing film * ''The Unknown'' (1915 drama film) * ''The Unknown'' (1927 film), a silent horror film starring Lon Chaney * ''The Unknown'' (1936 film), a ...

, although it was not included in a formal

phylogenetic analysis In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

. Later, some referred specimens were described and in 2010 its

cranial Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

anatomy was revised.

Classification

In Butler ''et al.'', 2011, the

postcrania Postcrania (postcranium, adjective: postcranial) in zoology and vertebrate paleontology is all or part of the skeleton apart from the skull. Frequently, fossil remains, e.g. of dinosaurs or other extinct tetrapods, consist of partial or isolated sk ...

l osteology was described for the first time and a large

confirmed its position as a basal ornithopod which was found to be closely related to another Chinese ornithopod, '' Jeholosaurus'' and later to the newly described Chinese ornithopod '' Haya''. Han ''et al.'' named this clade "Jeholosauridae" in 2012. The following

cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to ...

was based on analysis by Makovicky ''et al.'', 2011.

References

External links

''Changchunsaurus''
at Dinosaur.net.cn, with the article summary and photograph. (slow-loading) {{Portal bar, Dinosaurs, Cretaceous, China Cretaceous dinosaurs of Asia Fossil taxa described in 2005 Ornithischian genera