Roadian Stage

The first appearance of Jinogondolella nankingensis evolved from Meosogondolella lamberti is defined as the base of the Guadalupian Roadian Stage which is at 42.7 m above the base of the Cutoff Formation in Stratotype Canyon (west face, southern Guadalupe Mountains, located at 31.8767° N., 104.8768° W. in USA), 29 cm below the prominent shale band in the upper part of the limestone unit in the El Centro Member.