[N] 2006 Sonidosaurus saihangaobiensis
Xu, Xing; Zhang, Xiaohong; Tan, Qingwei; Zhao, Xijin; and Tan, Lin (2006) A New Titanosaurian Sauropod from Late Cretaceous of Nei Mongol, China. Acta Geologica Sinica Vol 80 No 1 pp. 20-26 Feb 2006 S. saihangaobiensis is named and described on the basis of the holotype and the only known specimen, which comprises several dorsal, sacral, and caudal vertebrae, several dorsal ribs, one anterior chevron, and much of the pelvis. Diagnostic features of the new species include a thick ridge extending down from the postzygapophysis on the lateral surface of the neural arch of the posterior dorsal vertebrae, a transversely oriented accessory lamina present between the anterior centroparapophyseal limina and the lateral centraprezygapophyseal lamina of the posterior dorsal vertebrae, long, anteroventrally directed caudal rib that bears two distinctive fossae on its posterior margin on the anterior caudal vertebrae and a prominent vertical ridge above the pubic peduncle on the medial surface of the ilium, among others. The ilium is pneumatic, a feature not common among non-avian dinosaurs. The new taxon has an unusual combination of primitive and derived character states. Preliminary character analysis shows a complex character distribution within the Titanosauriformes. Recent titanosauriform discoveries suggest that a significant radiation occurred in Asia early in the titanosauriform evolution.