Analyses of sediments from hundreds of meters beneath the Yucatán suggest that an extraterrestrial object's impact there more than 65 million years ago—the punch that many scientists propose wiped out the dinosaurs—actually happened about 300,000 years before those mass extinctions occurred. Many researchers reject the new conjecture, however.
At the heart of the debate is a 1.5-kilometer-long rock core that scientists drilled 2 years ago at a site 40 km southwest of Mérida, Mexico. That spot is near the edge of a gravitational and magnetic anomaly that many scientists interpret as a long-buried, 180-km-wide pockmark—the Chicxulub crater—that resulted from a space rock's hit.
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