GASTROPODS UNDERWENT A MAJOR TAXONOMIC TURNOVER DURING THE END-TRIASSIC MARINE MASS EXTINCTION EVENT

FERRARI MARIEL; MICHAEL HAUTMANN

PLOS ONE

PUBLIC LIBRARY SCIENCE

Lugar: San Francisco; Año: 2022

1932-6203

Based on anexhaustive database of gastropod genera and subgenera during theTriassic–Jurassic transition, origination and extinction percentages andresulting diversity changes are calculated, with a particular focus on theend-Triassic mass extinction event. We show that gastropods suffered a loss of 56% of genera and subgenera during this event, whichwas higher than the average of marine life (46.8 %). Among molluscs,gastropods were more strongly affected than bivalves (43.4 %) but lessthan ammonoids, which were nearly annihilated. However, there were alsopronounced differences among gastropod subclasses. The most strongly affectedsubclass was the Neritimorphia, which lost 72.7 % of their Rhaetian genera; onthe other extreme, the Heterobranchia remained nearly unaffected (11 % loss).We analysed this extinction pattern with respect to larval development,palaeobiogeography, shell size, and anatomy and found that putative feeding ofthe pelagic larval stage, adaptation to tropical-temperate water temperatures,and flexibility of the mantle attachment were among the factors that mightexplain extinction resilience of heterobranchs during the end-Triassic crisis.Among molluscs, extinction magnitude roughly correlates with locomotionactivity and thus metabolic rates. We suggest three potential kill mechanismsthat could account for these observations: global warming, ocean acidification,and extinction of marine plankton. The end-Triassic extinction of gastropodstherefore fits to proposed extinction scenarios for this event, which invokethe magmatic activity of the Central Atlantic Magmatic Province as the ultimatecause of death. With respect to gastropods, the effect of the end-Triassic massextinction was comparable to that of the end-Permian mass extinction. Notably, Heterobranchiawas relatively little affected by both events; the extinction resilience ofthis subclass during times of global environmental changes was therefore possiblya key aspect of their subsequent evolutionary success.