To Infer the early Evolution of Mollusc Shell Microstructures

Abstract

To infer the early evolution of mollusc shell microstructures we must know the most ancient fossil record of molluscs. Fortunately the shells of many early molluscs are preserved via internal coatings and replacements by apatite that record sub-micrometer structural details that otherwise would be lost during diagenetic recrystallization. We herein discuss the methodology by which one can infer original shell microstructure from phosphatized fossils, pointing out the main problems and solutions in interpreting these traces of original shell crystal morphology. We also review the information these fossils have provided about the earliest evolution of the mollusc shell. Our long-term goal is to create a dataset of microstructures in early molluscs, which will be useful in understanding the incipient evolutionary arms race between molluscs and their predators, and will help elucidate how the mollusc biomineralization toolkit was built through time.