LAUSR

Finely preserved fossil assemblages (lagerstätten) provide crucial insights into evolutionary innovations in deep time. We report an exceptionally preserved Early Triassic fossil assemblage, the Guiyang Biota, from the Daye Formation near Guiyang, South China. High-precision uranium-lead dating shows that the age of the Guiyang Biota is 250.83 +0.07/–0.06 million years ago. This is only 1.08 ± 0.08 million years after the severe Permian-Triassic mass extinction, and this assemblage therefore represents the oldest known Mesozoic lagerstätte found so far. The Guiyang Biota comprises at least 12 classes and 19 orders, including diverse fish fauna and malacostracans, revealing a trophically complex marine ecosystem. Therefore, this assemblage demonstrates the rapid rise of modern-type marine ecosystems after the Permian-Triassic mass extinction. Description Mass extinction rebellion The Triassic recovery of life from the devastating end-Permian mass extinction was an amazing period of evolution. Whether biodiversity had to rebuild from near annihilation or from refugia is a matter of conjecturebut recovery heralded the development of recognizably modern ecosystems. Dai et al. present examples of diverse fishes, ammonoids, bivalves, protists, and malacostracan arthropods from a fossil site dated approximately 1 million years after the crisis. These fossil assemblages, particularly the presence of vertebrate predators, reveal a surprisingly early diversity of animals after the end-Permian mass extinction. —CA and SNV The Guiyang Biota fossil assemblage reveals the rapid rise of a modern-type marine ecosystem after the Permian-Triassic mass extinction.