Roadian

The Roadian is a stage of the Permian period, representing the earliest stage of the Guadalupian, the middle division of the Permian. It follows the Kungurian stage of the Cisuralian (early Permian) and precedes the Wordian stage. In the International Chronostratigraphic Chart, the Roadian is used as a global timeslice for correlating Permian rocks and fossils across regions.

Temporal framework and duration are approximate and subject to refinement as stratigraphic dating improves. The Roadian is generally placed around the late Early Permian to early Middle Permian, with commonly cited age ranges spanning roughly from about 272 to 268 million years ago, though precise boundaries can vary by correlation scheme and regional stratigraphy.

Global correlations of the Roadian rely on fossil assemblages and stratigraphic markers. Conodonts, ammonoids, and fusulinids provide biostratigraphic signals that help define the base and top of the stage in many regions. In addition to biostratigraphy, magnetostratigraphy and sequence stratigraphy contribute to regional correlations and the construction of a continuous Permian timeline.

Paleogeography and environments during the Roadian reflect a world dominated by the supercontinent Pangaea, with extensive continental interiors that favored arid and semiarid climates in many areas, alongside shallow-m marine basins elsewhere. The fauna includes early therapsids and other amniotes on land, along with typical Permian marine and freshwater organisms. The Roadian is thus an important interval for understanding the diversification of Permian life and the broader ecological changes leading into the middle Permian.