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What Killed the Dinosaurs?

We already knew the rough outlines of the K-T extinction event that wiped out the dinosaurs about 66 million years ago. First a massive meteor hit the Yucatan Peninsula with the explosive force of over one billion atomic bombs, leaving an 112-mile crater and covering the world in ash and debris.

Then came the secondary environmental effects—most notably the deep freeze caused by the atmospheric changes, which scientists had long suspected killed the dinosaurs. But 66 million years is a pretty long time, and discovering direct evidence of these environmental effects wasn’t easy. Fortunately, scientists got lucky; by looking at the locations of some well-preserved thaumarchaeota fossils and other secondary temperature indicators, a team of Dutch paleoclimatologists were able to show a 13°F drop in ocean temperature consistent with a global freeze. They also found iridium deposits consistent with a large meteorite impact, though the massive crater had already clued us in on that.

It’s likely that similar larger-scale studies of the freshly-reshaped regions surrounding the Chicxulub crater will yield further evidence of temperature changes, but this year’s study will go down in history as the first direct evidence of a temperature drop during the K-T extinction event—which brings us closer to understanding just how the dinosaurs died. And while we don’t know whether or not the dinosaurs themselves had difficulty physically adapting to the colder temperatures, we can reasonably assume that the climate change had a ripple effect on their ecosystem. Species that could themselves adapt to cold often starved to death because the species they fed on (or the species that they, in turn, fed on) didn’t adapt as well. In the end, fewer than 25% of Earth’s species survived the K-T extinction event.

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Tom Head is an author or coauthor of 29 nonfiction books, columnist, scriptwriter, research paralegal, occasional hellraiser, and proud Jackson native. His book Possessions and Exorcisms (Fact or Fiction?) covers the recent demand for exorcists over the past 30 years and demonic possession.
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