Changchunsaurus
Encyclopedia
Changchunsaurus is an extinct genus
of small herbivorous ornithopod
dinosaur
from Early Cretaceous
deposits of Gongzhuling
, Jilin
, China
. It is the first named dinosaur genus from Jilin.
. The type
and only known species
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
of the Songliao Basin, dating to the Aptian
–Cenomanian
stages. Changchunsaurus is based on the holotype
JLUM L0403-j–Zn2, a skeleton
and skull
, with a premaxilla
(upper beak) and partial lower jaw 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
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
unknown
, although it was not included in a formal phylogenetic analysis
.
Later, some referred specimens were described and in 2010 its cranial anatomy was revised. In Butler et al., 2011, the postcrania
l osteology was described for the first time and a latge phylogenetic analysis
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
.
The following cladogram
was based on analysis by Makovicky et al., 2011.
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of small herbivorous ornithopod
Ornithopod
Ornithopods or members of the clade Ornithopoda are a group of ornithischian dinosaurs that started out as small, bipedal running grazers, and grew in size and numbers until they became one of the most successful groups of herbivores in the Cretaceous world, and dominated the North American...
dinosaur
Dinosaur
Dinosaurs are a diverse group of animals of the clade and superorder Dinosauria. They were the dominant terrestrial vertebrates for over 160 million years, from the late Triassic period until the end of the Cretaceous , when the Cretaceous–Paleogene extinction event led to the extinction of...
from Early Cretaceous
Early Cretaceous
The Early Cretaceous or the Lower Cretaceous , is the earlier or lower of the two major divisions of the Cretaceous...
deposits of Gongzhuling
Gongzhuling
-Administrative Divisions:Subdistricts:*Dongsan Subdistrict , Tiebei Subdistrict , Tiedong Subdistrict , Henan Subdistrict , Hebei Subdistrict Towns:...
, Jilin
Jilin
Jilin , is a province of the People's Republic of China located in the northeastern part of the country. Jilin borders North Korea and Russia to the east, Heilongjiang to the north, Liaoning to the south, and Inner Mongolia to the west...
, China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...
. 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 20052005 in paleontology
-New taxa:-New taxa:-Xiphosurans:* Fossils of Lunataspis, the earliest known xiphosuran, are discovered in Canada. It was not given a formal description until 2008, however.-New taxa:-Newly named dinosaurs:...
. The type
Type species
In biological nomenclature, a type species is both a concept and a practical system which is used in the classification and nomenclature of animals and plants. The value of a "type species" lies in the fact that it makes clear what is meant by a particular genus name. A type species is the species...
and only known species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
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
Quantou Formation
The Quantou Formation is a Mesozoic geologic formation. Dinosaur remains are among the fossils that have been recovered from the formation, although none have yet been referred to a specific genus.-See also:* List of dinosaur-bearing rock formations...
of the Songliao Basin, dating to the Aptian
Aptian
The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous epoch or series and encompasses the time from 125.0 ± 1.0 Ma to 112.0 ± 1.0 Ma , approximately...
–Cenomanian
Cenomanian
The Cenomanian is, in the ICS' geological timescale the oldest or earliest age of the Late Cretaceous epoch or the lowest stage of the Upper Cretaceous series. An age is a unit of geochronology: it is a unit of time; the stage is a unit in the stratigraphic column deposited during the corresponding...
stages. Changchunsaurus is based on the holotype
Holotype
A holotype is a single physical example of an organism, known to have been used when the species was formally described. It is either the single such physical example or one of several such, but explicitly designated as the holotype...
JLUM L0403-j–Zn2, a skeleton
Skeleton
The skeleton is the body part that forms the supporting structure of an organism. There are two different skeletal types: the exoskeleton, which is the stable outer shell of an organism, and the endoskeleton, which forms the support structure inside the body.In a figurative sense, skeleton can...
and skull
Skull
The skull is a bony structure in the head of many animals that supports the structures of the face and forms a cavity for the brain.The skull is composed of two parts: the cranium and the mandible. A skull without a mandible is only a cranium. Animals that have skulls are called craniates...
, with a premaxilla
Premaxilla
The incisive bone is the portion of the maxilla adjacent to the incisors. It is a pair of small cranial bones at the very tip of the jaws of many animals, usually bearing teeth, but not always. They are connected to the maxilla and the nasals....
(upper beak) and partial lower jaw 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
Derived
In phylogenetics, a derived trait is a trait that is present in an organism, but was absent in the last common ancestor of the group being considered. This may also refer to structures that are not present in an organism, but were present in its ancestors, i.e. traits that have undergone secondary...
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
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....
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 (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
unknown
Incertae sedis
, is a term used to define a taxonomic group where its broader relationships are unknown or undefined. Uncertainty at specific taxonomic levels is attributed by , , and similar terms.-Examples:*The fossil plant Paradinandra suecica could not be assigned to any...
, although it was not included in a formal phylogenetic analysis
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
.
Later, some referred specimens were described and in 2010 its cranial anatomy was revised. In Butler et al., 2011, the postcrania
Postcrania
Postcrania[p] in zoology and vertebrate paleontology refers to all or part of the skeleton apart from the skull. Frequently, fossil remains, e.g...
l osteology was described for the first time and a latge phylogenetic analysis
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
confirmed its position as a basal ornithopod which was found to be closely related to another Chinese ornithopod, Jeholosaurus
Jeholosaurus
Jeholosaurus is a genus of ornithischian dinosaur from the Early Cretaceous Period. It is thought to have been a small ornithopod presumably related to the hypsilophodonts, and an herbivore. Although the back teeth are like those of a plant eater, the front premaxillary teeth are sharp and pointed...
and later to the newly described Chinese ornithopod Haya
Haya (dinosaur)
Haya is an extinct genus of basal ornithopod dinosaur known from Mongolia.-Description:Haya is known from several well-preserved specimens which collected in the Khugenetslavkant locality by the joint Mongolian Academy of Sciences from 2002 to 2007, from the Javkhlant Formation. The locality...
.
The following cladogram
Cladogram
A cladogram is a diagram used in cladistics which shows ancestral relations between organisms, to represent the evolutionary tree of life. Although traditionally such cladograms were generated largely on the basis of morphological characters, DNA and RNA sequencing data and computational...
was based on analysis by Makovicky et al., 2011.
Paleobiology
As a small basal ornithopod, Changchunsaurus would have been a swift bipedal herbivore, feeding close to the ground.External links
- Changchunsaurus at Dinosaur.net.cn, with the article summary and photograph. (slow-loading)
- Changchunsaurus at Thescelosaurus! (under Ornithopoda i.s.).