Biogeochemistry of Brachiopod Intracrystalline Molecules [and Discussion]

Brachiopods contain both proteins and lipids within the biocrystals of their shell. One intracrystalline chromoprotein causes red shell coloration, whereas the other molecules may be involved with biomineralization, may strengthen the biocrystal, or may simply have been inadvertently engulfed by calcite during shell growth. Evidence is presented which suggests that at least some of the breakdown products of indigeneous intracrystalline molecules can be recovered from the biocrystals of fossil brachiopod shells. Investigations of the remains of these intracrystalline molecules in fossils have geological application in fields such as environmental reconstruction, isotopic determinations, taxonomy and the interpretation of colour in extinct organisms.