Scientists say they have found signs of a devastating meteorite which hit Australia millions of years ago.
While the surface crater from the strike has long disappeared, scientists from Australian National University said that by drilling more than a mile deep into the Earth, they found a 250-mile (400km) wide impact area deep inside the Earth's crust.
The researchers believe the meteorite broke into two halves just before it hit Earth between 300 and 600 million years ago.
Analysis showed the Earth's crust fractured at depths of more than 12 miles under the intense heat and pressure generated by the strike, the study revealed in the journal Tectonophysics .
"The two asteroids must each have been over 10km across - it would have been curtains for many life species on the planet at the time," said lead researcher Andrew Glikson.
"Large impacts like these may have had a far more significant role in the Earth's evolution than previously thought," Dr Glikson said.
The impact would have sent huge clouds of ash and dust into the atmosphere, altering the planet's temperature and possibly causing the demise of a number of different species.
Despite the size of the hit, scientists have not yet connected it with a specific period of extinction on Earth.
"It's a mystery - we can't find an extinction event that matches these collisions," Dr Glikson said.
"I have a suspicion the impact could be older than 300 million years."
The most devastating meteorite to hit the Earth that scientists know about currently is the one that arrived 66 million years ago and led to the extinction of the dinosaur.