Another Questioning of the Guadalupian Mass Extinction

High-precision temporal calibration of Late Permian vertebrate biostratigraphy: U-Pb zircon constraints from the Karoo Supergroup, South Africa

Authors:

1. Bruce S. Rubidge (a)
2. Douglas H. Erwin (b,c)
3. Jahandar Ramezani (d)
4. Samuel A. Bowring (d)
5. William J. de Klerk (e)

Affiliations:

a. Bernard Price Institute for Palaeontological Research, School of Geosciences, University of the Witwatersrand, PO Wits, Johannesburg 2050, South Africa

b. Department of Paleobiology, National Museum of Natural History, Washington, D.C. 20560, USA

c. Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, New Mexico 87501, USA

d. Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA

e. Department of Geology and the Albany Museum, Rhodes University, Grahamstown 6140, South Africa

Abstract:

Therapsid and other tetrapod fossils from the South African Karoo Supergroup provide the most detailed and best studied terrestrial vertebrate record of the Middle and Late Permian. The resulting biostratigraphic scheme has global applicability. Establishing a temporal framework for these faunas has proven difficult: magnetostratigraphy has been hampered by a Jurassic overprint, and intercorrelation with Permian marine sequences has been equivocal. Here we report U-Pb zircon isotope dilution–thermal ionization mass spectrometry (ID-TIMS) dates for five volcanic ashes interbedded with fossils from the Pristerognathus, Tropidostoma, and Cistecephalus vertebrate biozones of the Beaufort Group. This temporal framework allows correlation to marine zonations and improves understanding of rates of faunal evolution and patterns of basin evolution. Our results identify no correlative vertebrate extinctions in the Karoo Supergroup to the marine end-Guadalupian mass extinction and raise the question of whether there is any record of a terrestrial extinction related to the Emeishan large igneous province.