An updated scenario for the end-Permian crisis and the recovery of Triassic land flora in Argentina

Abstract

The end-Permian crisis was the most severe extinction event in the Phanerozoic. In SouthwesternGondwana, this crisis was related to the development of the Choiyoi Silicic Large Igneous Province. In the Southern Hemisphere, the Glossopteridales were dominant in the Permian, and they declined at thePermian-Triassic boundary and were replaced by the Dicroidium flora. Argentinean Permian and Triassicfloras are known for more than a century, but, in most recent years, new stratigraphic schemes and moreaccurate geochronological information have put in question the previous evolution models. Here we proposed a new scenario for the vegetation evolution during the Permian?Triassic boundary and earlyMiddle Triassic in Argentina. During the Wuchiapingian?early Changhsingian interval, the floras weredominated by Glossopteridales, Cordaitales, Asterothecaceae, and Voltziales, and the oldest record ofUmkomasiales(=Corystospermales), Peltaspermales, and Cycadales occurs. The Glossopteris flora would have disappeared in the Changhsingian before the end-Permian crisis. The late Changhsingian vegetation was dominated by cycads typical of the Dicroidium flora surviving in a refuge zone. After the end-Permian crisis, the recuperation was carried out by corystosperms, cycads and sphenophytes in the Induan? Olenekian interval. The Anisian plant communities were well-stabilised and diverse, corresponding to radiation of the Dicroidium flora.