Cope IL, Wilkinson JJ, Boyce AJ, Herrington RJ (2010)
Oxygen Isotope Composition of Hematite: Pic de Fon Deposit, Republic of Guinea, West Africa.
In the decades following the discovery of the PETM, numerous other hyperthermals have been discovered, marked by coeval excursions in the carbon and
oxygen isotope compositions of benthic foraminifera and bulk sediment.
Both the eggshells and the embryo bones were analyzed in order to determine
their oxygen isotope composition.
Taking these measurements into account, the researchers — assisted by a physiologist colleague — were able to model the different developmental stages integrating
the oxygen isotope compositions.
[2]
The oxygen isotope composition refers to the relative abundance of oxygen's two main stable isotopes, oxygen - 16 (16O) and oxygen - 18 (18O).