Roadian

[7] The base of the Roadian is defined as the place in the stratigraphic record where fossils of conodont species Jinogondolella nankingensis first appears.

The global reference profile for the base (the GSSP) is located in Stratotype Canyon in the Guadalupe Mountains, Texas (31°52′36″N 104°52′36″W / 31.87667°N 104.87667°W / 31.87667; -104.87667).

The top of the Roadian (the base of the Wordian Stage) is at the first appearance of fossils of conodont species Jinogondolella aserrata.

Some studies suggested that Olson’s Extinction, a worldwide loss of terrestrial vertebrate life occurred during the Early Guadalupian (Roadian, Wordian),[8] but the temporal resolution of most studies only indicates that this possible extinction event indicates around the Kungurian/Roadian boundary.

[9][10] Studies using higher-resolution stratigraphic data and the fossilized birth-death model suggest that this even is actually a slow decline over 20 Ma that started in the Sakmarian and that may have extended into the Roadian.