and 35 caudal vertebrae, with only the last several missing. Also missing from the skeleton were most of the forelimbs and the skull. When M. hochuanensis was first described, it was the largest sauropod known from China.

In 1958, Young described a mamenchisaur specimen (IVPP V. 946) from the Haishiwan region of Yongdeng, Gansu Province. This specimen was initially assigned to M. constructus. However, in 1972 it was reassigned to M. hochuanensis as a paratype. This specimen was slightly smaller than the holotype and consisted of less