Chaohusaurus

Chaohusaurus is an extinct genus of basal ichthyopterygian, depending on definition possibly ichthyosaur, from the Early Triassic of Chaohu and Yuanan, China. The type species Chaohusaurus geishanensis was named and described by Yang Zhongjian and Dong Zhiming in 1972, based on a fossil found during the construction of a railway. The generic name refers to lake Chao Hu. The specific name refers to the Geishan location. The holotype, IVPP V 4001, was uncovered in a layer of the Majianshan Limestone Formation dating from the Anisian. It consists of a partial skeleton, containing the skull and the front torso. In 1985 Chen Lizhu named two additional species based on fossils found in the same formation: Anhuisaurus chaoxianensis and Anhuisaurus faciles. However, the generic name had already been preoccupied by the lizard Anhuisaurus Hou 1974. Therefore, Anhuisaurus Chen 1985 was in 1991 renamed into Chensaurus by Jean-Michel Mazin e.a. In 1998, Ryosuke Motani and Hailu You established that the Chensaurus fossils represented remains of juveniles, with those of C. faciles being the youngest, and that these formed a growth series with Chaohusaurus. This implied that the known material of Chaohusaurus was increased with the specimens AGM P45-H85-25, the holotype of Chensaurus chaoxianensis; AGM P45-H85-20, the holotype of Chensaurus faciles; and the front flippers IVPP V 11361 and IVPP V 11362. In 2001 a detailed description of the osteology of Chaohusaurus was published by Michael Maisch. In 2014, three additional specimens were reported: AGM I-1, AGM CHS-5, and AGM CH-628-22. AGM I-1 also contains the remains of three embryo's. The new finds are part of recent discoveries by a Chinese-Italian paleontological project of eighty Chaohusaurus fossils. In 2013, a second species was named and described by Chen Xiaohong e.a.: Chaohusaurus zhangjiawanensis. The specific name refers to its provenance near the village of Zhangjiawan. The holotype, WHGMR V26001, was uncovered in a layer of the Jialingjang Formation dating from the Spathian.