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$A dinosaur tooth discovered along what\'s now the Kakanaut River of northeastern Russia. The tooth shows dinosaurs once lived above the Arctic Circle. Credit: Pascal Godefroit$

A dinosaur tooth discovered along what's now the Kakanaut River of northeastern Russia. The tooth shows dinosaurs once lived above the Arctic Circle. Credit: Pascal Godefroit

clipped from: www.livescience.com

Even accounting for continental drift, the dinos lived at more than 70 degrees of latitude north, well above the Arctic Circle.

And they weren't lost wanderers, either. The fossils include dinosaur eggshells — a first at high latitudes, and evidence of a settled, breeding population.

It's true the Arctic was much warmer back then, but it wasn't any picnic. The size and shape of fossilized leaves found with the bones enabled Godefroit's team to estimate a mean annual temperature of 50 degrees Fahrenheit, with wintertime lows at freezing.

Yet there is more than one way to skin a dino. All that dust in the atmosphere must have curtailed photosynthesis everywhere, weakening the base of the food chain and inflicting starvation, and finally extinction, upon the dinosaurs.