[D] Yunnanosaurus youngi
Lü, Li, Zhong, Azuma, Fujita, Dong & Ji Q. 2007
Jurassic Middle Jurassic Late
Saurischia Sauropodomorpha Prosauropoda Yunnanosauridae
Zhanghe Formation, Banqing Houshanliangzi of Jiangyi, Yuanmou County of Yunnan Province, China
Yunnanosaurus huangi (Young, 1942) > Yunnanosaurus robustus (Young, 1951) Yunnanosaurus youngi (Lü, Li, Zhong, Azuma, Fujita, Dong & Ji Q. 2007)
The specific name is in honor of Professor Young C. C., a distinguished paleontologist who was the first to study the dinosaurs from the Lufeng Basin (Lower Lufeng Formation) and erected the family Yunnanosauridae in 1942.
A partial complete skeleton without skull, pectoral girdle, forelimb and hindlimb. The specimen is stored in the Chuxiong Museum (CXMVZA 185)
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 Yunnanosaurus huangi and it represents a derived form of yunnanosaurids.
A new species of yunnanosaurid differs from Yunnanosaurus huangi in the following characters larger size, body length approximate 13 meters long the sixth cervical vertebra is the longest among the vertebral column the neural spines of posterior cervical vertebrae are short with expanded distal end, which is wider than its anteroposterior length three sacral vertebrae are tightly fused with a stout sacrocostal yoke the ventral margin of the postacetabular process of the ilium slightly concave ischium longer than pubis distal end of the pubis is round.