A new study press release planetary scientists have found evidence of a meteor impact much larger and earlier than the one that killed the dinosaurs - an impact that they believe caused the biggest mass extinction in Earth's history.
The 300-mile-wide crater lies hidden more than a mile beneath the East Antarctic Ice Sheet. And the gravity measurements that reveal its existence suggest that it could date back about 250 million years - the time of the Permian-Triassic extinction, when almost all animal life on Earth died out.
Its size and location - in the Wilkes Land region of East Antarctica, south of Australia - also suggest that it could have begun the breakup of the Gondwana supercontinent by creating the tectonic rift that pushed Australia northward.
Read more about this facinating discovery by Ohio State University researchers.