Oct. 2017 ACTA GEOLOGICA SINICA (English Edition) Vol. 91 No. 5 1529 http://www.geojournals.cn/dzxben/ch/index.aspx of Yumenerpeton and that of all the other bystrowianids. On the other hand, the primitive sculpture type of Yumenerpeton in Middle Permian in China affirms this suggestion. The shape of scutes of Yumenerpeton yangi is more or less similar to that of chroniosuchids in some degree. The features observed in Yumenerpeton yangi may warrant the close proximity or phyletic succession of the chroniosuchid and bystrowianid types of the osteoderm design. In conlusion,yumenerpeton can be classified in the subfamily Bystrowianinae. The vaulted type of scutes presenting in Yumenerpeton in this study and other undescribed scutes of bystrowianids in Dashankou of the same locality (original observation by Jiang Shan) suggests that this character may share by Bytrowianinae, Dromotectinae and Axitectinae in Middle Permian or even earlier. And the former lose this feature while the Dromotectinae-Axitectinae keep it in evolution, probably. The shape of scutes of Yumenerpeton yangi is more or less similar to that of chroniosuchids in some degree. The features observed in Yumenerpeton yangi may warrant the close proximity or phyletic succession of the chroniosuchid and bystrowianid types of the osteoderm design. 5 Conclusion (1) In this study, we present evidence for their existence in the Middle Permian of China, based on well preserved diagnostic vertebrae with associated osteoderms from the Dashankou fanua in northwestern China. (2) The finds clearly show interosteoderm articulation pattern between the adjacent scutes in bystrowianids. (3) The features observed in Yumenerpeton yangi may warrant the close proximity or phyletic succession of the chroniosuchid and bystrowianid types of the osteoderm design. Acknowledgements Many thanks are given to Prof. Liu Yongqing, Prof. Li Daqing, and Guo Xiangqi, Peng Nan, Xue Peilin for their help in the field; to Mr. Cui Guihai for skillful preparation specimens and Prof. Liu Jun for his comments and improvement on the manuscript. This research was funded by the China Geological Survey (Grant No. 1212011120139). Manuscript received June 12, 2016 accepted Nov. 18, 2016 edited by Fei Hongcai References Benton, M.J., Shishkin, M.A., Unwin, D.M., and Kurochkin, E.N., 2000. The Age of Dinosaurs in Russia and Mongolia, United Kingdom: Cambridge University Press, 60 70. Golubev, V.K., 1998a. Narrow-armored chroniosuchians (Amphibia, Anthracosauromorpha) from the Late Permian of Eastern Europe. Paleontological Journal, 32: 278 287. Golubev, V.K., 1998b. Revision of the Late Permian chroniosuchians (Amphibia, Anthracosauromorpha) from Eastern Europe. Paleontological Journal, 32: 390 401. Golubev, V.K, 1999. A new narrow-armored chroniosuchian (Amphibia, Anthracosauromorpha) from the Late Permian of the East Europe. Paleontological Journal, 33: 166 173. Golubev, V. K., 2000. Permian and Triassic chronosuchians and biostratigraphy of the upper Tatarian deposits of Eastern Europe by tetrapods. Trudy Paleontologischeskogo Instituta, 276: 1 176. Translated by Michael J. Benton, 2011: 84 88, 117 129. Jiang Shan, 2014. New Chroniosuchians (Amphibia) from the Middle Permian in Yumen, Gansu and the Related Stratigraphy. Chinese Academy of Geological Sciences (Master Thesis in Chinese), 1 88. Li Jinling, and Cheng Zhengwu, 1999. New antheracosaur and temnospondyl amphibians from Gansu, China. Vertebrata Palasiatica, 37(3): 234 247 (in Chinese with English abstract). Liu Jun, Xu Li, Jia Songhai, Pu Hanyong and Liu Xiaoling, 2014. The Jiyuan tetrapod fauna of the Upper Permian of China 2. stratigraphy, taxonomical review, and correlation. Vertebrata Palasiatica, 52(3):328 339. Schoch, R., Voigt, S., and Buchwitz, M., 2010. A chroniosuchid from the Triassic of Kyrgyzstan and analysis of chroniosuchian relationships. Zoological Journal of the Linnean Society, 160: 515 530. Shishkin, M.A., Novikov, I.V., and Fortuny, J., 2014. New bystrowianid chroniosuchians (Amphibia, Anthracosauromorpha) from the Triassic of Russia and diversification of Bystrowianidae. Paleontological Journal, 48 (5): 512 522. Witzmann, F., Schoch, R.R., and Maisch, M., 2008. A relict basal tetrapod from Germany: first evidence of a Triassic chroniosuchian outside Russia. Naturwissenschaften, 95: 67 72. Young, C.C., 1979. A new Late Permian fauna from Jiyuan, Henan, Vertebrata Palasiatica, 17(2): 99 113 (in Chinese). About the first author JIANG Shan: obtained MS from the Institute of Geology, Chinese Academy of Geological Sciences. She is currently interested in study of the Mesozoic reptiles (Paleontology and Stratigraphy). Tel: 18086037737 Email: j_s2016@126.com