( CNN ) The massive meteorite split in two shortly before smashing into Earth , wiping out large numbers of species . The devastating event took place on our planet many millions of years ago , but researchers are only now beginning to discover what happened . In a remote part of Central Australia , the two pieces of asteroid left what geophysicists say is the largest impact zone ever found on Earth , spreading over an area 400 kilometers ( 250 miles ) wide . `` The two asteroids must each have been over 10 kilometers across -- it would have been curtains for many life species on the planet at the time , '' said lead researcher Andrew Glikson of the Australian National University . The team published its research in the journal Tectonophysics this month . The crater caused by the asteroids vanished long ago . But Glikson said the researchers stumbled across scars from the impacts during drilling for geothermal research . Traces are buried more than 2 kilometers inside the Earth 's crust , under an area near the borders of South Australia , Queensland and the Northern Territory . `` There are two huge deep domes in the crust , formed by the Earth 's crust rebounding after the huge impacts , and bringing up rock from the mantle below , '' Glikson said . The researchers are still trying to figure out just how long ago the shattering event happened . The surrounding rocks are 300 million to 600 million years old , according to the team , but they have n't been able to find the sort of evidence left by other meteorite strikes . A big meteorite strike that is believed to have led to the extinction of many dinosaur species 66 million years ago launched a plume of ash into the air that now shows up as a layer of sediment in rocks . But the researchers say they have n't come across a similar layer in sediments from about 300 million years ago . `` It 's a mystery -- we ca n't find an extinction event that matches these collisions . I have a suspicion the impact could be older than 300 million years , '' Glikson said . The discovery of the huge asteroid impacts could lead to new insights about the Earth 's history . `` Large impacts like these may have had a far more significant role in the Earth 's evolution than previously thought , '' Glikson said . CNN 's Jessica King contributed to this report .
Two pieces of asteroid crashed into South Australia many millions of years ago . Researchers stumble across traces of the impact zone deep in the earth 's crust .