Latest studies suggest that comet impact 55 million years ago may have caused mammals domination on Earth.
According to common theory it could have triggered a rapid phase of global warming linked to the expansion of mammal groups, however American researchers came up with new evidence: it is believed some spherical fragments of glass found recently were formed when molten debris flung out by an impact solidifies in mid-air. But this interpretation has been debated by other experts.
It was proved before that space impacts have had profound effects on Earth’s ecosystems, like an asteroid slammed into Yucatan peninsula in Mexico 66 million years ago caused the dinosaurs disappearance.
One of the co-authors of the new study, Dennis Kent, from Rutgers University suggests the glass fragments could have come from 10km-wide comet slamming into the Atlantic Ocean.
Dennis Kent, from Rutgers University, a co-author of the new study, thinks the glass found in sediment cores drilled along the New Jersey coast could have come from a 10km-wide comet slamming into the Atlantic Ocean. He thinks it may be the reason of the mysterious release of CO2 and other greenhouse gases, which warmed the planet so quick 55.6 million years ago. This warm period from remote past is often compared to today’s rapid human-induced climate change.
As a temperature increased the mammal groups started spreading to new parts of the world and formed three groups that are still with us today: the Artiodactyla, the Perissodactyla and the Primates – the mammalian order that includes humans. Modern Artiodactyls include sheep, pigs, camels and giraffes, while today’s Perissodactyls include horses, tapirs, rhinos and zebras.
Orthodox theories suggest the global warming phase, which lasted about 200,000 years, was caused by sources closer to home – such as volcanism. But the author of new theory came up with controversial idea: spherical fragments of glass contain an interesting mineral known as microtektites. This mineral, called lechatelierite, “forms at really high temperatures – about 1,700C”, said Prof Kent. The presence of this mineral is not easy to explain, but volcanic magma has for sure much lower temperatures.
The second evidence supports new theory is the discovery of grains of shocked quartz in one of the spherules. These kind of shocked grains occur under very intensive pressure produced by a cosmic collision, the pressures in a volcano are not sufficient to produce these grains.
Prof Koeberl informed the BBC News website that the spherule evidence “indicates that an impact event may have occurred at that time – but only if the spherules are really unambiguously of [Palaeocene-Eocene] age. He added: “What I am also noting is that the spherules are extremely modest and extremely rare… this suggests both a far-absent resource (but the restricted size range is continue to unconventional) or a somewhat modest influence occasion.
“Equally possibilities do not indicate a key affect on the Earth’s weather. Even much more substantial situations… have had no significant or discernible affect on the weather. In this respect I feel any recommendation that an influence occasion induced the PETM is not supported by the knowledge.”
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