Morphological innovation after mass extinction events in Permian and Early Triassic conodonts based on Polygnathacea

Abstract

Taxonomic diversity of marine animals decreased markedly during the end-Guadalupian and end-Permian mass extinctions, but conodonts were largely unaffected by these two major events. This conclusion is largely based on potentially problematic conodont taxonomy, but quantitative analyses of conodont morphology have received little attention, despite offering key insights into macroevolutionary dynamics. Polygnathacea conodonts seemingly evolved fast and had high morphological diversity, and are therefore ideal for exploring morphospace trends and disparity related to environmental change in conodonts. Here we compiled discrete character-taxon matrices to first refine phylogenetic interpretations and then explore morphological disparity in four related conodont families, the Anchignathodontidae, Sweetognathidae, Idiognathodontidae and Vjalovognathidae, from the Permian to Early Triassic. Our findings reveal morphological innovation and exploration of new morphospace after the end-Guadalupian mass extinction and end-Permian mass extinction. We also show that the smaller end-Guadalupian extinction event was more impactful, resulting in greater losses of morphological disparity and taxonomic diversity, than the larger end-Permian extinction event. Overall, our study reveals morphological disparity trends related to temporal evolutionary dynamics for conodonts during the geologically and environmentally turbulent Permian and Early Triassic. We show that conodonts are affected by extinction events during this interval in terms of morphological diversity, rather than simply taxonomic diversity.