Dianchungosaurus
Encyclopedia
Dianchungosaurus is an extinct genus
of mesoeucrocodylia
n crocodylomorph
from the Early Jurassic
of China
. It was previously considered a dinosaur
, but it was recently reclassified as a mesoeucrocodylian by Paul Barrett and Xing Xu (2005). It is probably the same animal as the informally named
"Tianchungosaurus".
The type species is D. lufengensis.
Both remains come from the Lower Lufeng Formation, in the Yunnan Province in China. The age of the material is thus Sinemurian
(Early Jurassic).
, Dianchungosaurus lufengensis affinities were doubted by some, who regarded it as a nomen dubium, but it was until recently usually considered a valid heterodontosaurid. In 2005, a paper by Barrett and Xu focused on this problematic taxon and found its specimens to form an hypodigm, a chimera
of different animals. The holotype, IVPP V4735a, was reclassified as a mesoeucrocodylian, while the paratype, IVPP V4735b, was found to be an indeterminate prosauropod.
To maintain the stability in the literature, the holotype retains the name D. lufengensis, while the paratype awaits a formal description.
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 mesoeucrocodylia
Mesoeucrocodylia
Mesoeucrocodylia is the name of the clade that includes Eusuchia and the paraphyletic group Mesosuchia. The group appeared during the Early Jurassic, and continues to the present day....
n crocodylomorph
Crocodylomorpha
The Crocodylomorpha are an important group of archosaurs that include the crocodilians and their extinct relatives.During Mesozoic and early Tertiary times the Crocodylomorpha were far more diverse than they are now. Triassic forms were small, lightly built, active terrestrial animals. These were...
from the Early Jurassic
Early Jurassic
The Early Jurassic epoch is the earliest of three epochs of the Jurassic period...
of 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 was previously considered a 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...
, but it was recently reclassified as a mesoeucrocodylian by Paul Barrett and Xing Xu (2005). It is probably the same animal as the informally named
Nomen nudum
The phrase nomen nudum is a Latin term, meaning "naked name", used in taxonomy...
"Tianchungosaurus".
The type species is D. lufengensis.
Material
Two specimens were originally referred to this taxon:- IVPPInstitute of Vertebrate Paleontology and PaleoanthropologyThe 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...
V4735a (holotypeHolotypeA 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...
): an isolated premaxilla. - IVPP V4735b (paratypeParatypeParatype is a technical term used in the scientific naming of species and other taxa of organisms. The exact meaning of the term paratype when it is used in zoology is not the same as the meaning when it is used in botany...
): cojoined partial left and right dentaries with teeth and left splenial
Both remains come from the Lower Lufeng Formation, in the Yunnan Province in China. The age of the material is thus Sinemurian
Sinemurian
In the geologic timescale, the Sinemurian is an age or stage in the Early or Lower Jurassic epoch or series. It spans the time between 196.5 ± 2 Ma and 189.6 ± 1.5 Ma...
(Early Jurassic).
Systematics
Originally classified by Yang in 1982 in HeterodontosauridaeHeterodontosauridae
Heterodontosauridae is a family of early ornithischian dinosaurs that were likely among the most basal members of the group...
, Dianchungosaurus lufengensis affinities were doubted by some, who regarded it as a nomen dubium, but it was until recently usually considered a valid heterodontosaurid. In 2005, a paper by Barrett and Xu focused on this problematic taxon and found its specimens to form an hypodigm, a chimera
Chimera (paleontology)
In paleontology, a chimera is a fossil which was reconstructed with elements coming from more than a single species of animal. A now classic example of chimera is Protoavis.-List of paleontological chimeras:*Brontosaurus*Lametasaurus...
of different animals. The holotype, IVPP V4735a, was reclassified as a mesoeucrocodylian, while the paratype, IVPP V4735b, was found to be an indeterminate prosauropod.
To maintain the stability in the literature, the holotype retains the name D. lufengensis, while the paratype awaits a formal description.
External links
- Dianchungosaurus in the Paleobiology Database