Trace Fossils as a Proxy of the Big 5 Biotic- and Environmental Events in the Phanerozoic

In this paper, we review the biotic and environmental events by examining the trace fossi1 records in association with the'Big5' mass extinctions in Phanerozoic, including the transitions of Ordovician-Silurian, Frasnian-Famennian, Permian- Triassic, Triassic-Jurassic and Cretaceous-Paleogene. The benthic fauna reflected in the trace fossi1 records show a negative re- sponse to all of the'Big5' events, documented by the decreases in the ichnodiversity, burrow size, bioturbation depth, and ichnofabric tier. The behavior and food-feeding strategy of benthic fauna is found to vary among the'Big5' mass extinctions. The deposit-feeding strategy dominated after the mass extinctions during 〇rdovician-Silurian and Cretaceous-Paleogene transi- tions, whilst the suspension-feeding strategy dominated after the mass extinction during Triassic-Jurassic transition. Opportun- istic trace fossils, such as Planolites, and both the deposit- and suspension-feeding strategies dominated after the mass extinc- tions during Frasnian-Famennian and Permian-Triassic transitions. The benthic ecosystems, reflected in the trace fossi1 records after the mass extinctions during Frasnian-Famennian and Permian-Triassic transitions, changed from simple to complex pat- tern, from two-dimensiona1 to three-dimensiona1 ecospace.