[D] Eomamenchisaurus yuanmouensis [sG] [T]
Lü, Li, Zhong, Ji and Li. 2008
Saurischia Sauropodomorpha Sauropoda Euhelopodidae
Zhanghe Formation, Yunnan Province, China
A new mamenchisaurid dinosaur, Eomamenchisaurus yuanmouensis gen et sp. nov. is erected based on an incomplete skeleton from the Zhanghe Formation, the Middle Jurassic of Yuanmou, Yunnan Province. The new taxon is characterized by absence of pleurocoels in dorsal vertebrae with slightly convex anterior articular surfaces, moderately concave posterior articular surfaces; the fourth trochanter is developed posteromedially on the femur; length ratio of the tibia to the femur is approximately 0.64; and the shaft of the ischium is rod-like. Two fused centra of the posterior dorsal vertebrae (the presumed 9th and the 10th dorsal vertebrae) are similar to those in other mamenchiasurid dinosaurs, including Mamenchisaurus hochuanensis. Mamenchisaurus youngi and Chuanjiesaurus anaensis. Therefore, fusion of centra of the ninth and the tenth dorsal vertebrea can be recognized as a synapomorphic chararcter of the Mamenchisauridae.
Eo-, Greek, beginning, Eomamenchisaurus means an early mamenchisaurid dinosaur. The specific epithet refers to the Chinese administrative unit Yuanmou County, Yunnan Province, were the type locality is located
CXMVZA 165 consisting of eight dorsal vertebrae, a partial sacrum,a right ilium, a right complete pubis, two incomplete ischia, one complete right tibia, and both femora. The specimen is strored in the Chuxiong Museum.
Type locality and horizon
Banqing Houshanliangzi of Jiangyi, Yuanmou County of Yunnan Province, Zhanghe Formation
A Primitive mamenchisaurid dinosaur with dorsal vertebrae lacking pleurocoels; anterior articular surfaces of dorsal vertebrae flat to slightly convex; posterior articular surface moderately concave; neural spines of third and fourth sacral vertebrae weakly fused; postacetabular process of the ilium present, shaft of ischium straight and longer than pubis; cross-section of mid-shaft of ischium sub-oval; the fourth trochanter placed on posteromedial margin of femur; length ratio of tibia to femur approximately 0.64