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Published October 2015 | Supplemental Material
Journal Article Open

Isotopic ordering in eggshells reflects body temperatures and suggests differing thermophysiology in two Cretaceous dinosaurs


Our understanding of the evolutionary transitions leading to the modern endothermic state of birds and mammals is incomplete, partly because tools available to study the thermophysiology of extinct vertebrates are limited. Here we show that clumped isotope analysis of eggshells can be used to determine body temperatures of females during periods of ovulation. Late Cretaceous titanosaurid eggshells yield temperatures similar to large modern endotherms. In contrast, oviraptorid eggshells yield temperatures lower than most modern endotherms but ~6 °C higher than co-occurring abiogenic carbonates, implying that this taxon did not have thermoregulation comparable to modern birds, but was able to elevate its body temperature above environmental temperatures. Therefore, we observe no strong evidence for end-member ectothermy or endothermy in the species examined. Body temperatures for these two species indicate that variable thermoregulation likely existed among the non-avian dinosaurs and that not all dinosaurs had body temperatures in the range of that seen in modern birds.

Additional Information

© 2015 Macmillan Publishers Limited. Received 19 October 2014. Accepted 07 August 2014. Published 13 October 2015. R.A.E. was supported by a Caltech Chancellors Postdoctoral Fellowship and by National Science Foundation grants EAR-1024929 to J.M.E. and R.A.E., ARC-1215551 to R.A.E. and A.K.T., a LabEx International Research Chair funded by the 'Laboratoire d'Excellence' LabexMER(ANR-10-LABX-19) and co-funded by a grant from the French government under the programme 'Investissements d'Avenir', and a funded visiting Associate Professor position at the Natural History Museum of Denmark. A.K.T. was supported by a Hellman Fellowship, and National Science Foundation grant EAR-0949191. T.T. was supported by DFG grants TU 148/2-1 and TU 148/4-1. M.J.K. acknowledges NSF grant EAR-1251443. We thank the Los Angeles Zoo, the Zurich Zoo, San Francisco Zoo, South Carolina Zoo, Gemarkenhof Farm in Germany, The Western Foundation of Vertebrate Zoology, and Colorado Gators for provision of modern eggshells. We thank the American Natural History Museum, the Natural History Museum of Los Angeles County and the Goldfuß Museum of the University of Bonn for provision of specimens for this study. Eggshell specimens from Montana that were not considered in the main text were from the Museum of the Rockies and Montana State and were kindly provided by Frankie Jackson. We also thank Marcus Clauss (University of Zurich) for provision of the compilations of ectotherm body temperatures and Frank Corsetti (University of Southern California) for use of petrographic microscopes. Miguel Rincon and Lowell Stott (University of Southern California) assisted with trace-element analysis. Contributions: R.A.E. designed the experiments, carried out isotopic analysis, analysed the data and wrote the manuscript. M.E. performed petrographic examinations with input from G.G.-T., S.J.L. and P.R. A.P.-H. carried out EBSD analysis and contributed to data interpretation. Geochemical analysis was carried out in the laboratories of J.M.E. and A.K.T. M.K. provided input on design of a modern eggshell sample set. D.H. performed some of the analysis. G.G.-T., S.M., L.M.C., T.T. and T.E.C. provided specimens for analysis and input into data interpretation. All authors provided input on the manuscript text. The authors declare no competing financial interests.

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