New research says that a comet, not an asteroid, is likely what caused the extinction of dinosaurs.
Dartmouth University researchers say that the over 100-mile Chicxulub crater in Mexico was created by something smaller than previously believed.
The crater is believed to have been the site of impact for the space rock that killed the dinosaurs.
It was previously postulated that an asteroid made the hole in the Earth but the new findings suggests the impact was from something smaller and faster: a comet.
The basis for the finding is a reevaluation of iridium levels - an element found in high levels around the impact site, suggesting that the crater was made by a rock from space.
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Iridium was compared to levels of the element osmium, which was also dispersed during the impact.
Researchers said that the new calculation means the rock created less debris than thought, meaning it was a smaller object that crashed into Earth.
"How do we get something that has enough energy to generate that size of crater, but has much less rocky material?" study author Jason Moore, a paleoecologist at Dartmouth, told BBC News.
That brings us to comets,"
The findings were presented at the 44th Lunar and Planetary Science Conference in The Woodlands, Texas.