Richard A. Kerr
Geologists may have found a piece of the rock that killed the dinosaurs. A sample of 65-million-year-old ooze from the North Pacific has yielded what seems to be a fossil meteorite, just millimeters across. It fell into the sediments at the same geologic instant as a 10-kilometer object struck the Yucatán, probably triggering the mass extinction that wiped out the dinosaurs. Assuming the rock is a piece of the shattered impacter, its composition implies that the dinosaur killer was an asteroid, not a comet, as some researchers have speculated.