Data from: δ18O-derived incubation temperatures of oviraptorosaur eggs

In order to determine the incubation temperature of eggs laid by non-avian
dinosaurs, we analysed the oxygen isotope compositions of both eggshell
carbonate (δ18Oc) and embryo bone phosphate (δ18Op) from seven
oviraptorosaur eggs with preserved in ovo embryo bones. These eggs come
from the Upper Cretaceous Nanxiong Formation of Jiangxi Province, China.
Oviraptorosaur theropods were selected because of their known brooding
behaviour as evidenced by preserved adult specimens fossilized in brooding
posture on their clutch. Incubation temperature of these embryos was
estimated based on the following considerations: eggshell δ18Oc value
reflects the oxygen isotope composition of egg water fluid; embryo bones
precipitate from the same egg fluid; and oxygen isotope fractionation
between phosphate and water is controlled by the egg temperature. A
time-dependent model predicting the δ18Op evolution of the embryo skeleton
during incubation as a function of egg temperature was built, and measured
δ18Oc and δ18Op values used as boundary conditions. According to the model
outputs, oviraptorosaurs incubated their eggs within a 35–40°C range,
similar to extant birds and compatible with the known active brooding
behaviour of these theropod dinosaurs. Provided that both eggshell and
embryo bones preserved their original oxygen isotope compositions, this
method could be extended to investigate some reproductive traits of other
extinct groups of oviparous amniotes.