Rapid Dino Extinction Theory Gains New Support

A recent fossil discovery gives renewed credence to a theory of massive and swift extinction

New evidence suggests the reign of the dinosaurs ended not with a whimper, but with a bang. Already, previous geological evidence of an apocalyptic meteor impact in what is now Mexico had led some paleontologists to believe in a massive extinction event. Now, the discovery of fossilized dinosaurs and eggshells in northeastern Russia supports the theory of a rapid extinction some 66 million years ago.

The shells are the first found at such a northerly latitude. The rich biodiversity of these fossils, which indicates that the dinosaurs weren't just visiting but lived in the locale, refutes the competing theory of gradual decline from a variety of factors such as loss of habitat, introduction of predators, and appearance of disease -- similar to the circumstances of many amphibians today. This lack of evidence for a long, slow decline is, according to the theory, a positive sign that there was, instead of a decline, a swift extinction.

But it's hardly conclusive. The odd geographical position of the site makes the fossil find fertile ground for argument on both sides of the rapid extinction debate. Accustomed to living at an average temperature of 50 degrees Fahrenheit, these cold-resistant species would have fared considerably better than tropical dinosaurs if a meteor strike initiated global cooling, for instance; so the rapid extinction theory does not provide a full accounting for their disappearance.

Despite remaining mysteries, this surprising discovery of cold-dwelling dinosaurs who were not just surviving, but flourishing soon before a potential doomsday-meteor impact is making many paleontologists rethink the world of 66 million years ago.

[Via Nature]