If the crater really was formed at the time von Frese and
colleagues believe, it will raise interest as a possible cause of
the "great dying" - the biggest of all of Earth's mass extinctions
when 95% of all marine life and 70% of all land species disappeared.
Some scientists have long suspected that the extinction at the
boundary of the Permian and Triassic (PT) Periods could have
occurred quite abruptly - the result of environmental changes
brought on by the impact of a giant space rock.
It is a similar argument to the one put forward to explain the
demise of the dinosaurs at the much later date of 65 million years
A geological structure, known as the Bedout High, in the seabed
off the northern coastal border of what is now Western Australia, has also been suggested as the possible
crater remains from the PT impactor.
But the impact explanation for the great dying is an argument
that has struggled to find favour.
The prevailing theory is that several factors - including
supervolcanism (where Magma rises from the earth's mantle and
accumulates in the crust. The heat of the liquid rocks causes more
of the solid crust to melt, forming a magma chamber which often
causes the pressure to rise more and more and can lead to eruptions
on such a massive scale that an ice age can be triggered as a
result), and extensive climate warming - combined over
thousands of years to strangle the planet's biodiversity.
Earth may well have been hit by extraterrestrial objects, but it
is unlikely there was some killer punch from space, these other
The Ohio-led team used gravity fluctuations measured by the US
space agency's Grace satellites to peer beneath Antarctica's icy
surface. Team members were drawn from the US, Russia and Korea.
The crater information was first presented at the recent
American Geophysical Union Joint Assembly in Baltimore.