Multiple paths to recovery after the Permian-Triassic mass extinction

Area of Science:

• Paleontology
• Evolutionary Biology
• Marine Ecology

Background:

• Biodiversity accumulation over millions of years is punctuated by mass extinction events.
• Understanding how surviving lineages rebuild diversity post-extinction is crucial for evolutionary studies.

Purpose of the Study:

• To examine the morphological and taxonomic recovery of ammonoids, brachiopods, and ostracods after the Permian-Triassic mass extinction (PTME).
• To identify distinct recovery trajectories and the factors influencing long-term taxonomic diversity growth.

Main Methods:

• Utilized a deep learning tool for automatic extraction of morphological features.
• Applied quantitative taxonomic diversity measures to analyze recovery patterns.
• Investigated three marine clades (ammonoids, brachiopods, ostracods) that experienced selective extinction during the PTME.

Main Results:

• Identified two primary recovery modes: 'refilling' (ammonoids, brachiopods) and 'expansion' (ostracods).
• Ammonoids and brachiopods showed limited innovation, partially recovering disparity and taxonomic diversity.
• Ostracods underwent adaptive radiation, expanding their morphospace and ecological niches, exceeding pre-extinction diversity by the Jurassic.

Conclusions:

• Rapid morphological diversification can drive ecological expansion and sustained taxonomic diversity.
• The PTME fundamentally reshaped marine ecosystems by inducing varied recovery paths among survivors.
• Different clades exhibited distinct strategies for rebuilding biodiversity after a major extinction event.