Could a Comet Have Slain the Dinosaurs?

Abstract

Imagine a peaceful, steamy night with mighty Triceratops drinking water from a pond, watching for their enemy Tyrannosaurus rex. Brighter than the brightest stars, a comet dominates the night. For several weeks now, the comet has brightened as it approached the sun, its long tail making it look like a sword in the sky. By the next afternoon, it is all over. With large thunderclaps and a huge crash, the comet slams into the Earth in what is now the Caribbean basin, just off the coast of the present-day Yucatán. Unlike a small me-teoroid, which glows brightly as it encounters the atmosphere and is vaporized, the comet is so large that it plows through as if the air weren’t even there. High walls of water race out from the point of impact, and millions of tons of dust surge upward in a gigantic cloud. The excavated material rushes out with such force that it quickly circles the Earth. All over the world, the sky is blindingly bright with meteors as the debris reenters; the light and heat make the atmosphere like a furnace. Intense as it is, the meteor storm lasts for half an hour as the surface is bombarded with debris, and surface temperatures are as high as an oven set to broiling. Dry vegetation ignites everywhere (soot in exposed rocks from that time provides evidence of worldwide ground fires).