''Dianchungosaurus'' (meaning " Dianchung lizard") is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

mesoeucrocodylia Mesoeucrocodylia is the clade that includes Eusuchia and crocodyliforms formerly placed in the paraphyletic group Mesosuchia. The group appeared during the Early Jurassic, and continues to the present day. Diagnosis It was long known that M ...

crocodylomorph Crocodylomorpha is a group of pseudosuchian archosaurs that includes the crocodilians and their extinct relatives. They were the only members of Pseudosuchia to survive the end-Triassic extinction. During Mesozoic and early Cenozoic times, cro ...

from the

Early Jurassic The Early Jurassic Epoch (geology), Epoch (in chronostratigraphy corresponding to the Lower Jurassic series (stratigraphy), Series) is the earliest of three epochs of the Jurassic Period. The Early Jurassic starts immediately after the Triassic-J ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

. It was previously considered a

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 ...

, 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 In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

is ''D. lufengensis'' and it was described in 1982.C.-C. Young. (1982). n a new genus of dinosaur from Lufeng, Yunnan Selected Works of Yang Zhungjian. ''Science Press, Beijing'' 38-42 A second species, ''D. elegans'', was named in 1986,Zhao, (1986). The Cretaceous biota of China: Reptilia. in Hao, Su, Yu, Li, Li, Wang, Qi, Guan, Hu, Liu, Yang, Ye, Shou and Zang (eds.). ''The Cretaceous System of China. Stratigraphy of China''. 12, 67-73, plates XI, XII. but it has since become a synonym of the type species.

Material

Two specimens were originally referred to this taxon: * IVPP V4735a (

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 several ...

): an isolated premaxilla. *IVPP V4735b (

paratype In zoology and botany, a paratype is a specimen of an organism that helps define what the scientific name of a species and other taxon actually represents, but it is not the holotype (and in botany is also neither an isotype nor a syntype). Of ...

): cojoined partial left and right dentaries with teeth and left splenial Both remains come from the Lower

Lufeng Formation The Lufeng Formation (formerly Lower Lufeng Series) is a Lower Jurassic sedimentary rock formation found in Yunnan, China. It has two units: the lower Dull Purplish Beds/Shawan Member are of Hettangian age, and Dark Red Beds/Zhangjia'ao Member ar ...

, near Dianchung, in the

Yunnan Province Yunnan , () is a landlocked province in the southwest of the People's Republic of China. The province spans approximately and has a population of 48.3 million (as of 2018). The capital of the province is Kunming. The province borders the C ...

in China. The age of the material is thus

Sinemurian In the geologic timescale, the Sinemurian is an age and stage in the Early or Lower Jurassic Epoch or Series. It spans the time between 199.3 ± 2 Ma and 190.8 ± 1.5 Ma (million years ago). The Sinemurian is preceded by the Hettangian and is ...

(Early Jurassic).

Systematics

Originally classified by Young in 1982 in

Heterodontosauridae Heterodontosauridae is a family of ornithischian dinosaurs that were likely among the most basal (primitive) members of the group. Their phylogenetic placement is uncertain but they are most commonly found to be primitive, outside 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, Chimaera, or Chimaira (Greek for " she-goat") originally referred to: * Chimera (mythology), a fire-breathing monster of Ancient Lycia said to combine parts from multiple animals * Mount Chimaera, a fire-spewing region of Lycia or Cilicia ...

of different animals. The holotype, IVPP V4735a, was reclassified as a mesoeucrocodylian, while the paratype, IVPP V4735b, was found to be an indeterminate

sauropodomorph Sauropodomorpha ( ; from Greek, meaning "lizard-footed forms") is an extinct clade of long-necked, herbivorous, saurischian dinosaurs that includes the sauropods and their ancestral relatives. Sauropods generally grew to very large sizes, had lon ...

. To maintain the stability in the literature, the holotype retains the name ''D. lufengensis'', while the paratype awaits a formal description.

References

External links

''Dianchungosaurus''
in the Paleobiology Database {{Taxonbar, from=Q1827257 Early Jurassic crocodylomorphs Early Jurassic reptiles of Asia Jurassic China Prehistoric animals of China Sinemurian life Fossil taxa described in 1982 Nomina dubia Prehistoric pseudosuchian genera