Characterizing the biogeographic and taxonomic patterns of post-LOME (early Silurian) diversification of brachiopods

Abstract

Brachiopods experienced rapid recovery and initial radiation during early Silurian following the Late Ordovician Mass Extinction (LOME), yet macroevolutionary processes operating during this time have remained largely unexplored. This study investigates the diversification pattern of brachiopods following the Late Ordovician Mass Extinction (LOME), focusing on the Aeronian and Telychian, Llandovery, early Silurian. Using occurrence data from three ages spanning six time intervals, we analyze temporal trends, spatial distribution, and community structure changes through bootstrapped diversity estimates, segmented regression, Non-metric Multidimensional Scaling (NMDS), and network analysis. The study reveal complex patterns in brachiopod diversification during the early Silurian. Diversity peaked in early Aeronian and remained relatively stable, with minor fluctuations in Telychian. The radiation process was characterized by significant geographic expansion and reduced provincialism. The dominant brachiopod orders were replaced in an asynchronous fashion across different paleoplates, generally trending from Ordovician-type to Silurian-type brachiopods. Importantly, diversity patterns alone inadequately captures the full scope of macroevolutionary processes. The geographic expansion of brachiopods and shifts in taxonomic dominance emerge as crucial factors in understanding post-extinction recovery patterns, highlighting the multifaceted nature of brachiopod evolution during this period.