In recent years, Telychian conodont zonation and biostratigraphy have been greatly changed. The age of the Rongxi Formation (Lower Red Bed) could be late Aeronian, the lower and upper boundaries of the Huixingshao Formation (Upper Red Bed) are diachronous, with the range from late P.eopennatus Zone to P.amorphognathoides Zone; the Guandi and Chejiaba formations (Third Red beds) mainly occurred in Ozarkodina snajdri Zone to early O.crispa Zone, namely late Ludfordian of Ludlow. There are no Wenlock and early Ludlow (Gorstian) marine deposits in the Yangtze Platform.