HOW COMPILED AND INCORRECT CORRELATIONS CAN “CREATE” A MASS EXTINCTION: THE CASE OF EARLY PERMIAN TETRAPODS

Diversity from the published literature is compiled at the stage level, so extinctions within stages are concentrated at stage boundaries. This compiled correlation effect can create an apparent mass extinction. Incorrect correlations further confound diversity compilations by mixing taxa from different time intervals. As a striking example, compiled and incorrect correlations have created an apparent mass extinction of tetrapods late in the early Permian. This extinction (“Olson’s extinction”) relies heavily on a mis-correlation: rejecting the marine biostratigraphic evidence that there is a hiatus (Olson’s gap = part of Kungurian-Roadian) in the global Permian fossil record of tetrapods. This extinction also relies on diversity compiled at the marine stage level, not at the more detailed level of the land-vertebrate faunachrons (LVFs). Most of the fossil record of tetrapods of the later early Permian is from Texas-Oklahoma, so it provides the best section to evaluate early Permian tetrapod extinctions. Genus-level data from this best section indicate an increase in generic diversity from Sakmarian to Artinskian (34 to 48), and another increase in generic diversity from Artinksian to Kungurian (48 to 57). At the resolution of LVF, generic diversity decreases from Coyotean to Seymouran-Mitchellcreekian, increases in Redtankian, and then drops (- 17 genera) to Littlecrotonian. Extinction rates are highest during Redtankian (- 36 genera), and origination rates (+ 23 and 19 genera, respectively) are high during Redtankian and Littlecrotonian. Tetrapod extinctions in the best section thus are spread out through the early Permian LVFs. More detailed stratigraphic data from the Redtankian show a stepwise structure to some of the Redtankian extinctions. Thus, the only stratigraphically dense tetrapod record of the late early Permian, from the southwestern USA, indicates a succession of extinctions spread out from Redtankian through Littlecrontonian (Kungurian) time, not a single mass extinction. Olson’s gap remains a hiatus in the global record of Permian tetrapods. The claim that there was a mass extinction of tetrapods before or across the gap has relied on compiled and mistaken correlations to compress all of the extinctions of the Redtankian-Littlecrotonian and Olson’s gap into one event.