“…11) and, by extrapolating this rate down to an assumed temperature history, acquired numerical ages for fossil opercula. However, as is the case for Patella ( Demarchi, 2009 ;Demarchi et al, 2013a), serine decomposition in Porites does not appear to follow an exponential relationship, which indicates that the calibration is not suitable for extrapolation. Indeed the presence of a residual bound fraction in biomineral observed in high-temperature studies on avian eggshell , terrestrial gastropods (Penkman et al, 2008a), and marine gastropods (Demarchi et al, 2013a), suggests that liberation of free Ser, and hence [Ser]/[Ala] decomposition, is unlikely to conform to a simple pseudo-first order relationship.…”