Diagenesis and the reconstruction of paleoenvironments: A method to restore original δ18O values of carbonate and phosphate from fossil tooth enamel

Oxygen isotopes of East Asian dinosaurs reveal exceptionally cold Early Cretaceous climates

“…of bones are smaller and less densely intergrown than those of enamel (14), even though several case studies have shown that the original oxygen isotope composition can be preserved in Mesozoic reptile remains (7)(8)(9)(15)(16)(17). Although no method is available to demonstrate definitely whether or not the oxygen isotope composition of fossil vertebrate phosphate was modified by diagenetic processes, several ways to assess the preservation state of the primary isotopic record have been proposed [e.g., (14,(18)(19)(20)(21)]. Here the main argument supporting the preservation of the original oxygen isotope composition is the latitudinal variation of the offset observed between the δ 18 O p values of probable endotherms (dinosaurs and trytilodont synapsids) and ectotherms (turtles and crocodilians) that mimics present day variations of the offset observed between the δ 18 O p values of endotherms and ectotherms (Fig.…”

“…While the unique characters of these continental faunas have been the subject of various speculations about their biogeographic history, little attention has been paid to their possible climatic causes. Here we address this question using the oxygen isotope composition of apatite phosphate (δ 18 O p ) from various reptile remains recovered from China, Thailand, and Japan. δ 18 O p values indicate that cold terrestrial climates prevailed at least in this part of Asia during the Barremianearly Albian interval.…”

“…Here we address this question using the oxygen isotope composition of apatite phosphate (δ 18 O p ) from various reptile remains recovered from China, Thailand, and Japan. δ 18 O p values indicate that cold terrestrial climates prevailed at least in this part of Asia during the Barremianearly Albian interval. Estimated mean air temperatures of about 10 AE 4°C at midlatitudes (∼42°N) correspond to present day cool temperate climatic conditions.…”

Multiproxy reconstruction of the palaeoclimate and palaeoenvironment of the Middle Miocene Somosaguas site (Madrid, Spain) using herbivore dental enamel

“…On the other hand, Zazzo et al (2004) stated that microbially induced alterations may produce important changes in the 8 18 0P04…”

“…According to Zazzo et al (2004), this is important as it suggests that the 8 18 0C0 3 signal has not been modified. Interspecific differences in 8 18 0C03 values can also be interpreted from a palaeoecological point of view Kohn, 1996;Sponheimer and Lee-Thorp, 1999 …”