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Oxygen isotopes from biogenic apatites suggest widespread endothermy in Cretaceous dinosaurs

By Romain Amiot, Christophe Lecuyer, Eric Buffetaut, Gilles Escarguel, Frédéric Fluteau and François Martineau

Abstract

International audienceThe much debated question of dinosaur thermophysiology has not yet been conclusively solved despite numerous attempts. We used the temperature-dependent oxygen isotope fractionation between vertebrate body water (δ18Obody water) and phosphatic tissues (δ18Op) to compare the thermophysiology of dinosaurs with that of non-dinosaurian ectothermic reptiles. Present-day δ18Op values of vertebrate apatites show that ectotherms have higher δ18Op values than endotherms at high latitudes due to their lower body temperature, and conversely lower δ18Op values than endotherms at low latitudes. Using a data set of 80 new and 49 published δ18Op values, we observed similar and systematic differences in δ18Op values (Δ18O) between four groups of Cretaceous dinosaurs (theropods, sauropods, ornithopods and ceratopsians) and associated fresh water crocodiles and turtles. Expressed in terms of body temperatures (Tb), these Δ18O values indicate that dinosaurs maintained rather constant Tb in the range of endotherms whatever ambient temperatures were. This implies that high metabolic rates were widespread among Cretaceous dinosaurs belonging to widely different taxonomic groups and suggest that endothermy may be a synapomorphy of dinosaurs, or may have been acquired convergently in the studied taxa

Topics: Cretaceous, oxygen isotopes, apatite, dinosaur, crocodile, turtle, thermophysiology, [SDU.STU.PG] Sciences of the Universe [physics]/Earth Sciences/Paleontology
Publisher: Elsevier
Year: 2006
DOI identifier: 10.1016/j.epsl.2006.04.018
OAI identifier: oai:HAL:hal-00143831v1
Provided by: Hal-Diderot
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