Paleoecology of secondary tierers from Western Pangean tropical marine environments during the aftermath of the end-Permian mass extinction

Skeletobionts that colonized organic hard parts during the early and late aftermath of the end-Permian mass extinction had been undescribed previously. Evaluation of more than 7400 skeletonized benthic invertebrates and taphonomic processes reveal a general pattern of increasing diversity and abundances of skeletozoans through the Early Triassic in tropical marine environments on the coast of western Pangea (present-day western U.S.A.). Griesbachian age skeletobiont assemblages are dominated by episkeletozoans, while Spathian ones are dominated by endoskeletozoans. Bivalves were the primary hard substrate for the skeletozoans in all examined strata, most likely because they were the most abundant skeletonized benthic invertebrate. Microconchids are hypothesized to have behaved opportunistically during the immediate aftermath of the end-Permian mass extinction, and they had a strongly preferred association with Claraia. This and future studies of Early Triassic skeletobionts will contribute to further understanding arguably one of the most evolutionary significant intervals in Earth's history.