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New in Earth and Planetary Science Letters - Oxygen isotopes ... suggest widespread endothermy in Cretaceous dinosaurs

There's a new report in Earth and Planetary Science Letters
Volume 246, Issues 1-2 , 15 June 2006, Pages 41-54

Oxygen isotopes from biogenic apatites suggest widespread endothermy in Cretaceous dinosaurs

Romain Amiota, Christophe LÃcuyera, Corresponding Author Contact Information, E-mail The Corresponding Author, Eric Buffetautb, Gilles Escarguela, FrÃdÃric Fluteauc and FranÃois Martineaua


The 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 (Î18Obody water) and
phosphatic tissues (Î18Op) to compare the thermophysiology of dinosaurs with that of non-dinosaurian ectothermic reptiles.

Present-day Î18Op values of vertebrate apatites show that ectotherms have higher Î18Op values than endotherms at high
latitudes due to their lower body temperature, and conversely lower Î18Op values than endotherms at low latitudes.

Using a data set of 80 new and 49 published Î18Op values, we observed similar and systematic differences in Î18Op values (Î18O)
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 Î18O 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.


Heinz Peter Bredow

P.S. 1

There's a report (in German) about this at


P.S. 2

The report is downloadable as PDF file for 30 US$ (that's ludicrous!!!)

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