Single massive asteroid wiped out dinosaurs: study

Interesting to know that we keep discovering new things everyday.
Guess we dont know as much as we thought we did.I debated this going here or in Space Exploration,so i guessed and posted it here,if im wrong,plz move this to the correct area.

WASHINGTON (Reuters) - A single, gigantic asteroid slammed into Earth 65 million years ago, dooming the dinosaurs and many other species, scientists said on Thursday in a new study rebutting theories that multiple impacts did the deed.
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An examination of rock sediments drilled from five sites at the bottom of the Atlantic Ocean strongly supports the notion that one massive hunk of space rock caused the mass extinction, a research team led by University of Missouri-Columbia geology professor Ken MacLeod found.
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Scientists 26 years ago found a band of iridium -- a metal rare on Earth but common in meteorites -- dating to the end of the Cretaceous Period that suggested a big space rock had smashed into the Earth and blasted its remains around the globe. The subsequent discovery of the Chicxulub crater, dating to the same time, was hailed by many as the smoking gun.
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They propose that one or more additional big hunks of space rock later hit the Earth and finished the job, but the impact craters they would have left behind have not yet been found.
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MacLeod's team examined sediment drilled far below the sea surface about 2,800 miles from the Yucatan impact site, a location they believed to be ideal. Any rock samples taken too close to the crater may be altered by events that occurred immediately after the impact, like waves, earthquakes and landslides. Samples taken too far away may contain too little debris evidence from the impact.
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From the fossil record it is quite clear and without dispute that the dinosaurs and other species lived for at least several hundreds to a few thousands of years after the impact.

It would be more accurate to say the asteroid initiated a series of global changes that culminated in the mass extinction. And the extinction did not occur near instantaneously, as the media leads people to believe. The extinction even took centuries to completley unfold.