Dianchungosaurus (meaning "Dianchung lizard"[1]) is an extinct genus of mesoeucrocodylian 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).[2] It is probably the same animal as the informally named "Tianchungosaurus".[1] The type species is D. lufengensis and it was described in 1982.[1] A second species, D. elegans, was named in 1986,[3] but it has since become a synonym of the type species.[2]
Both remains come from the Lower Lufeng Formation, near Dianchung, in the Yunnan Province in China. The age of the material is thus Sinemurian (Early Jurassic).[2]
Originally classified by Young in 1982 in Heterodontosauridae,[1] 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 sauropodomorph.[2]
To maintain the stability in the literature, the holotype retains the name D. lufengensis, while the paratype awaits a formal description.[2]