Chiayusaurus
Encyclopedia
Chiayusaurus was a genus
of sauropod dinosaur
known from teeth
found in Asia
. Two species have been named for this obscure genus. It was originally named as Chiayüsaurus, but the ICZN
does not permit special characters, so it has become Chiayusaurus. The old name can still be seen in older sources, though.
based
Chiayusaurus on a tooth crown in the IVPP
. This tooth was found in the ?Tithonian
-age ?Upper Jurassic Keilozo (now Kalazha) Formation
of Xinjiang
, China
. This spatula
te tooth crown was 27 millimeters long (1.1 inches), and was not unlike that of the younger genus Asiatosaurus
. As it was based on such sparse material, it has largely been ignored or considered to be indistinguishable from other, better-known sauropods. For example, Russell and Zheng found its tooth to be indistinguishable from those of Mamenchisaurus.
Bohlin described a larger tooth in the 1953 publication as "Species A. (aff. Chiayüsaurus)", which he thought might belong to the type species
. In 1997, Lee, Yang, and Park described a new species from South Korea
based on a tooth (KPE 8001
) which they regarded as being identical to "Species A. (aff. Chiayüsaurus)". This new species, C. asianensis, is from the Aptian
-Albian
-age Lower Cretaceous Hasandong Formation
of Namdo, Gyeongsang
. The authors rejected the suggestion that Bohlin's two teeth may have differed from being in different places in the jaw, and separated their species on the basis of details of the wear surfaces and placement of ridges. The C. asianensis tooth crown is 46 mm long (1.8 in).
Both species were reviewed in 2002, by Barrett et al. They regarded the type tooth of C. lacustris as nearly identical to teeth of Euhelopus
, but were unable to conclusively establish synonymy
, finding it to be an indeterminate eusauropod
. They found that C. lacustris and C. asianensis shared no special features
, and instead differed. C. asianensis was regarded as a possible titanosauriform
, but still indeterminate.
In the most recent review of sauropods, both species were considered to be dubious
without comment.
al herbivore
.
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 sauropod 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...
known from teeth
Tooth
Teeth are small, calcified, whitish structures found in the jaws of many vertebrates that are used to break down food. Some animals, particularly carnivores, also use teeth for hunting or for defensive purposes. The roots of teeth are embedded in the Mandible bone or the Maxillary bone and are...
found in Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
. Two species have been named for this obscure genus. It was originally named as Chiayüsaurus, but the ICZN
International Code of Zoological Nomenclature
The International Code of Zoological Nomenclature is a widely accepted convention in zoology that rules the formal scientific naming of organisms treated as animals...
does not permit special characters, so it has become Chiayusaurus. The old name can still be seen in older sources, though.
History and taxonomy
Birger BohlinBirger Bohlin
Dr. Anders Birger Bohlin was a Swedish palaeontologist. As well as his work on dinosaurs and prehistoric mammals, Bohlin was part of the group that established the existence of Peking Man ...
based
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...
Chiayusaurus on a tooth crown in the IVPP
Institute of Vertebrate Paleontology and Paleoanthropology
The Institute of Vertebrate Paleontology and Paleoanthropology of China is a prominent research institution and collections repository for fossils, including many dinosaur and pterosaurand cat poo specimens...
. This tooth was found in the ?Tithonian
Tithonian
In the geologic timescale the Tithonian is the latest age of the Late Jurassic epoch or the uppermost stage of the Upper Jurassic series. It spans the time between 150.8 ± 4 Ma and 145.5 ± 4 Ma...
-age ?Upper Jurassic Keilozo (now Kalazha) Formation
Rock formation
This is a list of rock formations that include isolated, scenic, or spectacular surface rock outcrops. These formations are usually the result of weathering and erosion sculpting the existing rock...
of Xinjiang
Xinjiang
Xinjiang is an autonomous region of the People's Republic of China. It is the largest Chinese administrative division and spans over 1.6 million km2...
, 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...
. This spatula
Spatula
The term spatula is used to refer to various small implements with a broad, flat, flexible blade used to mix, spread and lift materials including foods, drugs, plaster and paints...
te tooth crown was 27 millimeters long (1.1 inches), and was not unlike that of the younger genus Asiatosaurus
Asiatosaurus
Asiatosaurus was a genus of herbivorous sauropod dinosaur which lived during the early Cretaceous. Its fossils have been found in China and Mongolia. It is known only from teeth, making it difficult to rely on information until more specimens are found to expand our knowledge.The type species, A....
. As it was based on such sparse material, it has largely been ignored or considered to be indistinguishable from other, better-known sauropods. For example, Russell and Zheng found its tooth to be indistinguishable from those of Mamenchisaurus.
Bohlin described a larger tooth in the 1953 publication as "Species A. (aff. Chiayüsaurus)", which he thought might belong to the type species
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...
. In 1997, Lee, Yang, and Park described a new species from South Korea
South Korea
The Republic of Korea , , is a sovereign state in East Asia, located on the southern portion of the Korean Peninsula. It is neighbored by the People's Republic of China to the west, Japan to the east, North Korea to the north, and the East China Sea and Republic of China to the south...
based on a tooth (KPE 8001
Kyungpook National University
Kyungpook National University , abbreviated as Kyungdae, is a leading national university in Daegu, South Korea. The university is one of 10 Flagship Korean National Universities. It is one of the three best recognized and oldest national universities with Seoul National University and Pusan...
) which they regarded as being identical to "Species A. (aff. Chiayüsaurus)". This new species, C. asianensis, is from 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...
-Albian
Albian
The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous epoch/series. Its approximate time range is 112.0 ± 1.0 Ma to 99.6 ± 0.9 Ma...
-age Lower Cretaceous Hasandong Formation
Hasandong Formation
The Hasandong Formation is a Mesozoic geologic formation. Dinosaur remains diagnostic to the genus level are among the fossils that have been recovered from the formation.-Paleofauna:* Chiayusaurus asianensis - "Tooth."...
of Namdo, Gyeongsang
Gyeongsang
Gyeongsang was one of the eight provinces of Korea during the Joseon Dynasty. Gyeongsang was located in the southeast of Korea....
. The authors rejected the suggestion that Bohlin's two teeth may have differed from being in different places in the jaw, and separated their species on the basis of details of the wear surfaces and placement of ridges. The C. asianensis tooth crown is 46 mm long (1.8 in).
Both species were reviewed in 2002, by Barrett et al. They regarded the type tooth of C. lacustris as nearly identical to teeth of Euhelopus
Euhelopus
Euhelopus is a genus of sauropod dinosaur that lived during the Early Cretaceous, between 130 and 112 million years ago . It lived in what is now Shandong Province in China. A large herbivore, it weighed approximately 15-20 tons and attained an adult length of 15m...
, but were unable to conclusively establish synonymy
Synonym (taxonomy)
In scientific nomenclature, a synonym is a scientific name that is or was used for a taxon of organisms that also goes by a different scientific name. For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies...
, finding it to be an indeterminate eusauropod
Sauropoda
Sauropoda , or the sauropods , are an infraorder of saurischian dinosaurs. They had long necks, long tails, small heads , and thick, pillar-like legs. They are notable for the enormous sizes attained by some species, and the group includes the largest animals to have ever lived on land...
. They found that C. lacustris and C. asianensis shared no special features
Synapomorphy
In cladistics, a synapomorphy or synapomorphic character is a trait that is shared by two or more taxa and their most recent common ancestor, whose ancestor in turn does not possess the trait. A synapomorphy is thus an apomorphy visible in multiple taxa, where the trait in question originates in...
, and instead differed. C. asianensis was regarded as a possible titanosauriform
Macronaria
Macronaria is a clade of sauropod dinosaurs from the Middle Jurassic to Late Cretaceous Periods of what are now North America, South America, Europe, Asia and Africa. The name means 'large nostrils' , in reference to the large nasal openings high on the head that probably supported fleshy...
, but still indeterminate.
In the most recent review of sauropods, both species were considered to be dubious
Nomen dubium
In zoological nomenclature, a nomen dubium is a scientific name that is of unknown or doubtful application...
without comment.
Paleobiology
As a sauropod, Chiayusaurus would have been a large, quadrupedQuadruped
Quadrupedalism is a form of land animal locomotion using four limbs or legs. An animal or machine that usually moves in a quadrupedal manner is known as a quadruped, meaning "four feet"...
al herbivore
Herbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
.