A new paper with free pdf:
Robin R. Dawson, Daniel J. Field, Pincelli M. Hull, Darla K. Zelenitsky, FranÃois Therrien and Hagit P. Affek (2020)
Eggshell geochemistry reveals ancestral metabolic thermoregulation in Dinosauria.
Science Advances 6(7) eaax9361
DOI: 10.1126/sciadv.aax9361
https://advances.sciencemag.org/content/6/7/eaax9361
Studying the origin of avian thermoregulation is complicated by a lack of reliable methods for measuring body temperatures in extinct dinosaurs. Evidence from bone histology and stableisotopes often relies on uncertain assumptions about the relationship between growth rate and body temperature, or the isotopic composition (Î18O) of body water. Clumped isotope (Î47) paleothermometry, based on binding of 13C to 18O, provides a more robust tool, but has yet to be applied across a broad phylogenetic range of dinosaurs while accounting for paleoenvironmental conditions. Applying this method to well-preserved fossil eggshells demonstrates that the three major clades of dinosaurs, Ornithischia, Sauropodomorpha, and Theropoda, were characterized by warm body temperatures. Dwarf titanosaurs may have exhibited similar body temperatures to larger sauropods, although this conclusion is provisional, given current uncertainties in taxonomic assignment of dwarf titanosaur eggshell. Our results nevertheless reveal that metabolically controlled thermoregulation was the ancestral condition for Dinosauria.
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