Phylum Chordata Order Nothosaur | Class Reptilia Family †Keichousauridae Rank Genus | |
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Similar Diandongosaurus, Qianxisaurus, Pararcus, Macroplacus, Serpianosaurus | ||
Dianopachysaurus is an extinct genus of pachypleurosaur known from the lower Middle Triassic (Anisian age) of Yunnan Province, southwestern China. It was found in the Middle Triassic Lagerstatte of the Guanling Formation. It was first named by Jun Liu, Olivier Rieppel, Da-Yong Jiang, Jonathan C. Aitchison, Ryosuke Motani, Qi-Yue Zhang, Chang-Yong Zhou and Yuan-Yuan Sun in 2011 and the type species is Dianopachysaurus dingi.
Dianopachysaurus is most closely related to Keichousaurus, another Chinese pachypleurosaur. Both belong to the family Keichousauridae. Pachypleurosaurs are hypothesized to have originated in the eastern Tethys Ocean (South China) before spreading and diversifying in the western Tethys in what is now Europe. A large ghost lineage of eastern pachypleurosaurs has long been inferred based on the phylogeny of the group. Dianopachysaurus represents an early stage in the radiation of pachypleurosaurs and its early age fills in much of the gap.