Preliminary assessment of coupling the analysis of shell microstructures and microtextures as palaeoecological indicator in fossil brachiopods

Abstract

Brachiopods are one of the most successful groups of marine invertebrates throughout the Phanerozoic. Despite their abundance and importance in the fossil record, there are numerous gaps in our understanding of their palaeoecology. In particular, there is little information about their mode of life in relation to the substrate, which can be important in palaeontological and sedimentological studies involving brachiopod faunas. The aim of this study is to test the combination of analyzing shell microstructures (with SEM) and microtextures (with EBSD) to elucidate palaeoecological aspects for three extinct species belonging to the Order Athyridida. Results indicate that Athyris spiriferoides and Composita ovata specimens have similar shell architecture to that of modern terebratulids, and were epifaunal species attached to a hard substrate by a pedicle. In contrast, Plicathyris ezquerrai has more shell similarities to modern rhynchonellids and likely had an epifaunal mode of life in a reclining position with ventral valve resting on the substrate. In summary, our ?ndings illustrate the usefulness of using a combined analysis of shell microstructures and microtextures in the study of brachiopod palaeoecology.