Differential Responses of Malvinoxhosan Brachiopod Faunas to Devonian Biotic Crises: A Quantitative Paleoecological Study Across Brazilian Intracratonic Basins

The term “diversity” has been used several times for the Brazilian Devonian fauna without considering its true ecological meaning, which may hinder a deeper understanding of this fauna over time. The main goal of this paper is to investigate the diversity patterns, origination and extinction rates of brachiopod throughout the Devonian in the Amazonas, Paraná, and Parnaíba basins, in order to assess how the global biotic crises impacted the fauna. The Ponta Grossa Formation (Pragian–Emsian), in Paraná Basin, exhibited the highest richness and diversity indexes, associated with moderate origination and extinction rates, reflecting a diverse and heterogeneous community. In the Amazonas Basin, the Maecuru Formation (Emsian–Eifelian) also showed peak richness and diversity, but with a high extinction rate, indicating a faunal renewal. In the Pimenteira Formation, Parnaíba Basin, high extinction rates and low origination contrast with the high origination, and no extinction records in the Cabeças Formation. Maximum diversity in the Paraná Basin occurred during the Zlíchov event interval, whereas the Amazonas and Parnaíba basins recorded high extinction rates during the same time. The Kačák event correlates with the final collapse of the endemic fauna, evidenced in the Amazonas Basin by the balanced rate of origination/extinction rates in the Barreirinha Formation and in the Paraná Basin by the post-crises community of the São Domingos Formation. The results emphasize that paleoecological trajectories were modulated by paleogeographic and local paleoenvironmental factors, as well as by the differential resilience of the Malvinoxhosan fauna, demonstrating that the Devonian biotic crises did not uniformly impact brachiopod faunas.