The Namurian Tsingyuan Formation from Ningxia, China, is divided into
three members. The remarkably well-preserved gastropods from the Tsing
yuan Formation belong to three assemblages: the Angyomphalus longicost
alus-Glabrocingulum tongxinensis assemblage from the Lower Member; an
assemblage of some siliceous Bellerophon sp., and Naticopsis sp. from
the Middle Member, and the Euphemites hindi-Turbonitella semisulcatus
assemblage from the Upper Member. Based on the associated ammonoids an
d conodonts, these assemblages are considered equivalent to the Eumorp
hoceras, Hamocerns(2)-Reticuloceras, and Reticuloceras(2) zones of Wes
t Europe respectively.