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Latest Cretaceous Polar Dinosaurs
Naturwissenschaften. 2008 Dec 16.
The last polar dinosaurs: high diversity of latest Cretaceous arctic dinosaurs
in Russia.Godefroit P, Golovneva L, Shchepetov S, Garcia G, Alekseev P.
Department of Palaeontology, Royal Belgian Institute of Natural Sciences, rue
Vautier 29, 1 000, Brussels, Belgium, Pascal.Godefroit@naturalsciences.be.
A latest Cretaceous (68 to 65 million years ago) vertebrate microfossil
assemblage discovered at Kakanaut in northeastern Russia reveals that dinosaurs
were still highly diversified in Arctic regions just before the
Cretaceous-Tertiary mass extinction event. Dinosaur eggshell fragments,
belonging to hadrosaurids and non-avian theropods, indicate that at least
several latest Cretaceous dinosaur taxa could reproduce in polar region and
were probably year-round residents of high latitudes. Palaeobotanical data
suggest that these polar dinosaurs lived in a temperate climate (mean annual
temperature about 10 degrees C), but the climate was apparently too cold for
amphibians and ectothermic reptiles. The high diversity of Late Maastrichtian
dinosaurs in high latitudes, where ectotherms are absent, strongly questions
hypotheses according to which dinosaur extinction was a result of temperature
decline, caused or not by the Chicxulub impact.