New hadrosauroid material from the Upper Cretaceous Majiacun Formation of Hubei Province, central China  

　　TAN Qing-wei   XING Hai   HU Yong-guo   TAN Lin   XU Xing 

Abstract   The Xichuan Basin is situated along the northwestern border between Henan and Hubei provinces in central China, and includes a thick accumulation of Upper Cretaceous sediments. Here we report and describe some indeterminate hadrosauroid material on the genus level, which was retrieved from the middle Majiacun Formation (Upper Cretaceous) in the southwestern area of the Xichuan Basin, northwest Hubei. The hadrosauroid remains occur with scattered dinosaur eggs at the same horizon. The majority of the bones may come from the late nestling and early juvenile stages. This condition could be best explained by the geographic segregation of the nestlings and early juveniles from the herd consisting of older individuals, as reported in some hadrosaurids. A minimum of two hadrosauroid taxa are identified through direct morphological comparisons: one may represent a relatively derived non-hadrosaurid hadrosauroid, and the other probably pertains to Hadrosaurinae. Considering the younger age of North American hadrosaurines, the presence of hadrosaurine material within the middle Santonian middle portion of the Majiacun Formation provides new evidence for the Asian origins of both Hadrosaurinae and Hadrosauridae. 

Key words   northwest Hubei, Late Cretaceous, middle Santonian, Majiacun Formation, Lijiagou bonebed, hadrosauroid