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

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

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 Me ...

crocodyliform Crocodyliformes is a clade of Crurotarsi, crurotarsan archosaurs, the group often traditionally referred to as "crocodilians". They are the first members of Crocodylomorpha to possess many of the features that define later relatives. They are the ...

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� ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

. It was previously considered a

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

, 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 International_Code_of_Zoological_Nomenclature, 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 spe ...

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 (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

): 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 (biology), isotype ...

): 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 a ...

, near Dianchung, in the

Yunnan Province Yunnan; is an inland Provinces of China, province in Southwestern China. The province spans approximately and has a population of 47.2 million (as of 2020). The capital of the province is Kunming. The province borders the Chinese provinces ...

in China. The age of the material is thus

Sinemurian In the geologic timescale, the Sinemurian is an age (geology), age and stage (stratigraphy), stage in the Early Jurassic, Early or Lower Jurassic epoch (geology), Epoch or series (stratigraphy), Series. It spans the time between 199.5 ±0.3 annu ...

(Early Jurassic).

Systematics

Originally classified by Young in 1982 in

Heterodontosauridae Heterodontosauridae is a family (biology), family of ornithischian dinosaurs that were likely among the most Basal (phylogenetics), basal (primitive) members of the group. Their phylogenetic placement is uncertain but they are most commonly fou ...

, ''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 lo ...

. 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 Crocodyliformes 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