The massive underwater crater left by the asteroid that exterminated the dinosaurs has provided new evidence that sea levels were much lower during the last Ice Age, researchers said.
Scientists worked on a platform off Mexico's east coast to dig for clues about the destruction of life 66 million years ago inside the 200-kilometer (125-mile) wide Chicxulub crater.
By chance, the researchers found evidence that the sea was much further away than the current coast line during the last Ice Age, which began 110,000 years ago and ended around 11,000 years ago, said mission leader Jaime Urrutia, president of the Mexican Academy of Science.
While a large part of the crater is now under the Gulf of Mexico, it was not submerged during the Ice Age.
"We discovered a circular structure at the bottom (of the sea)," Urrutia told a news conference.
"The only way that (such structures) are made is through the dissolution of carbonate and for carbonate to dissolve it must be exposed to air," he said.
This shows that the Yucatan peninsula was "literally much larger" between 18,000 and 23,000 years ago during the last Ice Age, the scientist said.
International geologists, paleontologists and microbiologists arrived on the Myrtle platform in the Gulf in April and worked there for two months, digging 1.5 kilometers (.93 mile) under the sea floor and extracting six tonnes of rock.
Some results of the studies have been published in the journal Science but the analysis continues at a laboratory in Bremen, Germany.
The 12-kilometer (7.4-mile) wide asteroid slammed the earth at a speed of 30 kilometers (18.6 miles) per second some 66 million years ago.
Its crater is unique on the planet because of its "peak ring" formation, a circular elevation as high as 500 meters with a 30-kilometer radius.
The platform was installed over one of the peaks to study the nature of the rocks below and how they took shape.
The scientists have yet to explain how the granite and molten rock petrified into peaks.
The first results show that the rocks moved up "like jelly," but while the rock was molten, the granite does not show signs of heating, Urrutia said.
The $15 million Expedition 364 was the first to peer into the undersea part of the Chicxulub crater.