Echinoids from the Tesero Member (Werfen Formation) of the Dolomites (Italy): implications for extinction and survival of echinoids in the aftermath of the end-Permian mass extinction

Jeffrey R Thompson; Renato Posenato; David J Bottjer; Elizabeth Petsios

doi:10.7717/peerj.7361

Echinoids from the Tesero Member (Werfen Formation) of the Dolomites (Italy): implications for extinction and survival of echinoids in the aftermath of the end-Permian mass extinction

PeerJ. 2019 Aug 30:7:e7361. doi: 10.7717/peerj.7361. eCollection 2019.

Authors

Jeffrey R Thompson^{1

2

3}, Renato Posenato⁴, David J Bottjer², Elizabeth Petsios³

Affiliations

¹ Department of Genetics, Evolution and Environment, University College London, University of London, London, United Kingdom.
² Department of Earth Sciences, University of Southern California, Los Angeles, CA, United States of America.
³ Department of Geosciences, Baylor University, Waco, TX, United States of America.
⁴ Dipartimento di Fisica e Scienze della Terra, Università di Ferrara, Ferrara, Italy.

Abstract

The end-Permian mass extinction (∼252 Ma) was responsible for high rates of extinction and evolutionary bottlenecks in a number of animal groups. Echinoids, or sea urchins, were no exception, and the Permian to Triassic represents one of the most significant intervals of time in their macroevolutionary history. The extinction event was responsible for significant turnover, with the Permian-Triassic representing the transition from stem group echinoid-dominated faunas in the Palaeozoic to Mesozoic faunas dominated by crown group echinoids. This turnover is well-known, however, the environmental and taxonomic distribution of echinoids during the latest Permian and Early Triassic is not. Here we report on an echinoid fauna from the Tesero Member, Werfen Formation (latest Permian to Early Triassic) of the Dolomites (northern Italy). The fauna is largely known from disarticulated ossicles, but consists of both stem group taxa, and a new species of crown group echinoid, Eotiaris teseroensis n. sp. That these stem group echinoids were present in the Tesero Member indicates that stem group echinoids did not go extinct in the Dolomites coincident with the onset of extinction, further supporting other recent work indicating that stem group echinoids survived the end-Permian extinction. Furthermore, the presence of Eotiaris across a number of differing palaeoenvironments in the Early Triassic may have had implications for the survival of cidaroid echinoids during the extinction event.

Keywords: Biodiversity; Bottleneck; Cidaroid; Recovery; Sea urchins; Triassic.

Grants and funding

This research was funded by United States National Science Foundation Grant IOS1240626 to David Bottjer. Renato Posenato was funded by the University of Ferrara (FAR 2018) and MIUR (Progetto Dipartimenti di Eccellenza 2018-22). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.