Validating marine Devonian biogeography: a study in bioregionalization

Abstract

The Devonian record presents an opportunity to test and validate an existing marine bioregionalization. This study is the first to use comparative biogeography and phylogenetic data to test Devonian bioregionalization. Proposed in the 1960s, the Old World, Eastern Americas and Malvinokaffric realms have been the functional standard for marine Devonian biogeography. Data from 32 published phylogenies of Devonian marine taxa, and a database of c. 800 occurrences were analysed using phylogenetic software to test for area monophyly. The taxic occurrences in our database were then tested against total fauna Devonian occurrences in the Paleobiology Database (https://paleobiodb.org) to identify differences in sampling. Results indicate that the current Devonian bioregionalization is not representative of natural areas and requires revision. The results highlight areas that are most robust from which the study makes recommendations to improve the process and diagnosis of Devonian biogeographical areas. We found that legacy issues within palaeontology are evident within the results and their interpretation. The validation of bioregionalization and process is critical to the advancement of biogeography and palaeontology. The sensitivity of bioregionalization shows biotic and geographical relationships, how life and earth evolved together, and how geographical bias is evident in scientific process.