Yunnanosaurus
Encyclopedia
Yunnanosaurus is a genus
of prosauropod dinosaur
from the Early to Middle Jurassic Period, a position in time that makes it one of the last prosauropods. It is closely related to Lufengosaurus
. Known from two valid species, Yunnanosaurus ranged in size from 7 meters (23 feet) long and 2 m (6.5 ft) high to 13 m (42 ft) long in the largest species.
(aka C. C. Young) discovered the first Yunnanosaurus skeletons in the Lufeng Formation of Yunnan
, China
. The fossil find was composed over twenty incomplete skeletons, including two skulls, and were excavated by Tsun Yi Wang.
However, scientists do not consider Yunnanosaurus to be especially close to the sauropods in phylogeny because the remaining portions of the animals body are distinctly prosauropod in design. This critical difference implies that the similarity in dentition between Yunnanosaurus and sauropods might be an example of convergent evolution
.
, Y. huangi, was named by C. C. Young
in 1942, and he erected the family Yunnanosauridae to contain it, though the family currently comprises only this genus and sometimes Jingshanosaurus
. Young also named a second species, Y. robustus, in 1951, but this has since been included
in the type species. The confusion in classification arose due to that the earliest specimens were of juveniles while the "Y. robustus" specimens represented fully grown adults.
In 2007, Lu and colleagues described another species of Yunnanosaurus, Y. youngi (named in honor of C. C. Young). In addition to various skeletal differences, at 13 meters (42 ft) long Y. youngi was significantly larger than Y. huangi (which reached only 7 meters [23 ft]), and Y. youngi is found later in the fossil record, hailing from the Middle Jurassic
.
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 prosauropod 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 the Early to Middle Jurassic Period, a position in time that makes it one of the last prosauropods. It is closely related to Lufengosaurus
Lufengosaurus
Lufengosaurus is a genus of prosauropod dinosaur which lived during the Early Jurassic period in what is now southwestern China.-Discovery and species:...
. Known from two valid species, Yunnanosaurus ranged in size from 7 meters (23 feet) long and 2 m (6.5 ft) high to 13 m (42 ft) long in the largest species.
Discovery
Yang ZhongjianYang Zhongjian
Yang Zhongjian , courtesy name Keqiang , also known as C.C. Young, was one of China's foremost paleontologists. He has been called the 'Father of Chinese vertebrate paleontology'...
(aka C. C. Young) discovered the first Yunnanosaurus skeletons in the Lufeng Formation of Yunnan
Yunnan
Yunnan is a province of the People's Republic of China, located in the far southwest of the country spanning approximately and with a population of 45.7 million . The capital of the province is Kunming. The province borders Burma, Laos, and Vietnam.Yunnan is situated in a mountainous area, with...
, 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...
. The fossil find was composed over twenty incomplete skeletons, including two skulls, and were excavated by Tsun Yi Wang.
Dentition
There were more than sixty spoon shaped teeth in the jaws of Yunnanosaurus, and were unique among prosauropods in that its teeth were self-sharpening because they "[wore] against each other as the animal fed." Scientists consider these teeth to be advanced compared to other prosauropods, as they share features with the sauropods.However, scientists do not consider Yunnanosaurus to be especially close to the sauropods in phylogeny because the remaining portions of the animals body are distinctly prosauropod in design. This critical difference implies that the similarity in dentition between Yunnanosaurus and sauropods might be an example of convergent evolution
Convergent evolution
Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...
.
Classification
The type speciesType 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...
, Y. huangi, was named by C. C. Young
Yang Zhongjian
Yang Zhongjian , courtesy name Keqiang , also known as C.C. Young, was one of China's foremost paleontologists. He has been called the 'Father of Chinese vertebrate paleontology'...
in 1942, and he erected the family Yunnanosauridae to contain it, though the family currently comprises only this genus and sometimes Jingshanosaurus
Jingshanosaurus
Jingshanosaurus is a genus of prosauropod dinosaurs from the Early Jurassic. Its fossils, a nearly complete skeleton including the skull, were found near the town of Jingshan , Lufeng County, Yunnan Province, China, from which the name derives. First described in 1995, the type species is J....
. Young also named a second species, Y. robustus, in 1951, but this has since been included
Inclusion (taxonomy)
In taxonomy, inclusion is the process whereby two species that were believed to be distinct are found in fact to be the same and are thus combined as one species...
in the type species. The confusion in classification arose due to that the earliest specimens were of juveniles while the "Y. robustus" specimens represented fully grown adults.
In 2007, Lu and colleagues described another species of Yunnanosaurus, Y. youngi (named in honor of C. C. Young). In addition to various skeletal differences, at 13 meters (42 ft) long Y. youngi was significantly larger than Y. huangi (which reached only 7 meters [23 ft]), and Y. youngi is found later in the fossil record, hailing from the Middle Jurassic
Middle Jurassic
The Middle Jurassic is the second epoch of the Jurassic Period. It lasted from 176-161 million years ago. In European lithostratigraphy, rocks of this Middle Jurassic age are called the Dogger....
.
External links
- Yunnanosaurus in the Dinosaur Encyclopaedia at Dino Russ's Lair