Terrestrial Ecology around the Permian–Triassic Boundary

Abstract

Permian–Triassic event is usually regarded as the greatest mass extinction in the Earth’s history, although detailed studies have shown that it was not very severe. Localities of fossil insects in European Russia, Tunguska and Kuznetsk basins, and Mongolia provide a unique (the best in the world) opportunity to study the preparation, course of the crisis, and restoration of the biota after it. It is generally believed that climatic changes causing the crisis resulted from eruption of the Siberian traps, so that localities of intertrappean deposits were undoubtedly formed during the crisis. Sedimentation conditions of volcanogenic deposits provide the most detailed time resolution, so that the crisis processes can be investigated in detail. The dynamics of insect diversity in the Paleozoic and basal Mesozoic shows that mass extinctions were absent, although many groups disappeared for some time from the taphonomic window. The crisis events in ecosystems appear earlier than events usually considered as the reason for crisis. The analysis of oryctocoenoses from localities of the intertrappean beds has shown that, during the formation of traps on the mountain plateau, rather diverse ecosystems were retained, including those of the forest formations. They are a source of information, allowing restoration of ecosystems at the end of the Early Triassic.