Nature of Biological Minerals and Diagenesis

Sta ble light iso tope ra tios (C/C and O/O) in fos sil teeth pro vide key ar chives for un der stand ing ecol ogy of past fau nal com mu ni ties and the evo lu tion of en vi ron ments dur ing the Plio-Pleis to cene. Given the in ev i ta ble pro cesses of diagenesis dur ing fos sili sa tion, the in teg rity of iso to pic in for ma tion and the de gree of de tailed in for ma tion that can be ex tracted, re main im por tant is sues in all fos sil stud ies. The most ap pro pri ate tests are those in trin sic to iso to pic abun dances in eco sys tems. They are eas ier to de velop for C/C in sa vanna en vi ron ments where large C/C dif fer ences ex ist be tween C4 trop i cal grasses and C3 trees and shrubs. Val i dat ing O/O ra tios in fos sil car bon ate or phos phate is more dif fi cult, but pat terned vari abil ity, mainly track ing wa ter-re lated be hav iour, within mod ern fau nal com mu ni ties has been rep li cated in sev eral fos sil as sem blages. The iden ti fi ca tion of sea sonal vari a tion in C/C and O/O along the growth axis of a tooth crown, also ap pli ca ble in ar eas com posed solely of C3 plants, fills a dual role as a test and for pro vid ing data on sea sonal am pli tude. The re sults of stud ies from lowand mid-lat i tude Af ri can sites sug gest that iso to pic vari a tion in rain fall on short timescales and eco log i cal dif fer ences amongst an i mals, dom i nate over smaller dif fer ences in O/O com po si tion due to tem per a ture.