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A new species of Yunnanosaurus, Y. youngi is erected. Y. youngi is larger and stratigraphically younger than Y. huangi.

SYSTEMATIC PALEONTOLOGY:
Saurischia Seeley, 1887
Sauropodomorpha Huene, 1932
Prosauropoda Huene, 1920
YunnanosauridaeYoung, 1942
Yunnanosaurus Young, 1942
Yunnanosaurus youngi sp. nov.

ETYMOLOGY:
The specific name is in honor of Professor Young C. C.

DESCRIPTION:
The holotype material of Yunnanosaurus youngi is a partial skeleton without the skull, pectoral girdle, fore and hind limbs. Y. youngi is from the early Middle Jurassic Zhanghe Formation of Jiangyi, Chuxiong of Yunnan Province, China. The Zhanghe Formation is stratigraphically younger than the Fengjiahe Formation where Y. huangi was found. Y. youngi is considered to be a derived member of the Yunnanosauridae.

REFERENCE:
Junchang LÜ, Tianguang LI, Shimin ZHONG,Yoichi AZUMA, Masato FUJITA, Zhiming DONG and Qiang JI. 2007. NEWYUNNANOSAURID DINOSAUR (DINOSAURIA, PROSAUROPODA) FROM THE MIDDLE JURASSIC ZHANGHE FORMATION OFYUANMOU,YUNNAN PROVINCE OF CHINA. Memoir of the Fukui Prefectural Dinosaur Museum 6: 1-15

ABSTRACT:
Yunnanosaurus youngi sp. nov. is erected based on the following characters: the distal ends of the sacral ribs expanded anteroposteriorly and dorsoventrally, forming into a sacrocostal yoke, which is contacting with the inner surface of ilium; the ischium is longer than the pubis.Yunnanosaurus youngi is about 13 meters long, which is longer than Yunnanosaurus huangi (7 meters long). The height exceeding the length for the centra of the posterior dorsal and anterior caudal vertebrae may be a synapopmorphy of Yunnanosauridae and Melanorosauridae. Yunnanosaurus youngi is stratigraphically younger than Y. huangi and it represents a derived form of yunnanosaurids.