Size variations in foraminifers from the Early Permian to the Late Triassic: implications for the Guadalupian-Lopingian and the Permian-Triassic mass extinctions

The final 10 Myr of the Paleozoic saw two of the biggest biologic crises in Earth history: the Middle Permian extinction (often termed the Guadalupian-Lopingian extinction, GLE) that was followed 7–8 Myr later by Earth’s most catastrophic loss of diversity, the Permian-Triassic mass extinction (PTME). These crises are not only manifest as sharp decreases in biodiversity and - particularly for the PTME - total ecosystem collapse, but they also drove major changes in biological morphological characteristics such as the Lilliput effect. The evolution of test size among different clades of foraminifera during these two extinction events has been less studied. We analyzed a global database of foraminiferal test size (volume) including 20226 specimens in 464 genera, 98 families, and 9 suborders from 632 publications. Our analyses reveal significant reductions in foraminiferal mean test size across the Guadalupian-Lopingian boundary (GLB) and the Permian-Triassic boundary (PTB), from 8.89 to 7...