An updated scenario for the end-Permian crisis and the recovery of Triassic land flora in Argentina
Josefina Bodnar, Eliana P. Coturel, Juan Ignacio Falco, Marisol Beltrán
Abstract
The end-Permian crisis was the most severe extinction event in the Phanerozoic. In Southwestern Gondwana, 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 the Permian–Triassic boundary and were replaced by the Dicroidium flora. Argentinean Permian and Triassic floras are known for more than a century, but recently, new stratigraphic schemes and more accurate 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 early Middle Triassic in Argentina. During the Wuchiapingian–early Changhsingian interval, the floras were dominated by Glossopteridales, Cordaitales, Asterothecaceae, and Voltziales, and the oldest record of Umkomasiales (=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.