IS THE LYSTROSAURUS ASSEMBLAGE ZONE OF THE KAROO BASIN, SOUTH AFRICA, THE EXPRESSION OF THE POST PERMIAN EXTINCTION ON LAND?
We report new paleontologic data, including plant-and-vertebrate fossils, that demonstrate the continuation of Dicynodon AZ taxa–reported as extinct at the assemblage zone boundary–into stratigraphically higher positions. These fossils are placed in a new lithostratigraphic, magnetostratigraphic, and geochonometric context, that differ from those reported previously from the Lootsberg Pass locality. The stratigraphy is dominated by normal magnetic polarity, with a short reverse-polarity zone in wacke and siltstone exposed immediately above a porcellanite. A U-Pb ID-TIMS age from this latter unit provides an early Changhsingian maximum depositional age and, in conjunction with our other data, we suggest that the Dicynodon–Lystrosaurus Assemblage-Zone boundary is not only stratigraphically higher than currently reported, but more than 1 Ma older than the Permian–Triassic extinction event in the marine realm.