The Ordovician–Silurian (~485–419 Ma) was a time of considerable evolutionary upheaval, encompassing both the largest evolutionary diversification and one of the first major mass extinctions. The Ordovician diversification coincided with global climatic cooling and paleocontinental collision, the ecological impacts of which were mediated by region-specific processes including substrate changes, biotic invasions, and tectonic movements. From the Sandbian–Katian (~453 Ma) onward, an extensive carbonate shelf developed in the eastern Baltic paleobasin in response to a tectonic shift to tropical latitudes and an increase in the abundance of calcareous macroorganisms. We quantify the contributions of environmental differentiation and temporal turnover to regional diversity through the Ordovician and Silurian, using brachiopod occurrences from the more shallow-water facies belts of the eastern Baltic paleobasin, an epicontinental sea on the Baltica paleocontinent. The results are consistent with carbonate shelf development as a driver of Ordovician regional diversification, both by enhancing broadscale differentiation between shallow- and deep-marine environments and by generating heterogeneous carbonate environments that allowed increasing numbers of brachiopod genera to coexist. However, temporal turnover also contributed significantly to apparent regional diversity, particularly in the Middle–Late Ordovician.

This upload contains the R scripts and data needed to replicate the analyses and data preparation in the manuscript. The data were originally downloaded from the Paleobiology Database (PBDB, https://paleobiodb.org) and the database of the Geoscience Collections of Estonia (SARV, https://geocollections.info).

To use this code and data, open the file baltic_calculations_neat_revised_26_02_21_neat.R, which explains what the different R scripts do and does most of the calculations and figure plotting in this manuscript.

functions_baltic_cleaning.R, 01_BS_lithologies.R, 02_BS_geokud.R, 03_BS_PBDB.R are for data downloads and cleaning

04_BS_diversity.R does capture-recapture diversity estimation

05_figs.R produces some of the figures.

make_supp_tables.R converts some of the results tables into tables in the Supplementary Material.

Results from the analyses are also included in this upload.