* Astronomy

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Chicxulub event

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Impact study: Princeton model shows fallout of a giant meteorite strike

Seeking to better understand the level of death and destruction that would result from a large meteorite striking the Earth, Princeton University researchers have developed a new model that can not only more accurately simulate the seismic fallout of such an impact, but also help reveal new information about the surface and interior of planets based on past collisions.
Princeton researchers created the first model to take into account Earth's elliptical shape, surface features and ocean depths in simulations of how seismic waves generated by a meteorite collision would spread across and within the planet. Current projections rely on models of a featureless spherical world with nothing to disrupt the meteorite's impact, the researchers report in the October issue of Geophysical Journal International.
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Paleontologist Kenneth Lacovara is looking deep in a New Jersey silt mine for the exact moment, 65 million years ago, when all dinosaurs perished.
That secret could be harder to uncover if the fossils here can no longer be unearthed after a housing and retail development is built on this open pit.
Lacovara, an associate professor of biology at Drexel University in Philadelphia, looks at this 40-foot deep hole at the end of a dirt road and sees a line in the sand where the Cretaceous period begins and ends. Below that line are dinosaurs, above it, not a single one.
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Cretaceous–Tertiary extinction event

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Chicxulub crater

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RE: Chicxulub event

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Dinosaur extinction link to crater confirmed

An international panel of experts has strongly endorsed evidence that a space impact was behind the mass extinction event that killed off the dinosaurs.
They reached the consensus after conducting the most wide-ranging analysis yet of the evidence.
Writing in Science journal, they rule out alternative theories such as large-scale volcanism.
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The extraterrestrial body that slammed into Earth 65 million years ago is best known for killing off the dinosaurs. But it also snuffed out more than 90% of the tiny plankton species that made up the base of the food web in the oceans. By sifting through geological records of ancient sediments from around the globe, palaeoceanographers have culled clues about how the impact caused so much havoc.
The researchers report in Nature Geoscience1 today that the most severe extinctions of nannoplankton happened in the northern oceans and that the ecosystems there took 300,000 years to recover, much longer than in the south.
Geological evidence suggests that the body that hit Earth was travelling from the southeast to the northwest.
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Credit: NASA/JPL/NGA

The topography of Mexico's Yucatan Peninsula reveals a subtle, but unmistakable, indication of the Chicxulub asteroid impact crater, believed by many scientists to be the cause of a mass extinction event 65 million years ago. In this computer-enhanced image, the crater's outer boundary is visible as the semi-circular, darker green line in the peninsula's upper left corner: a trough only 3 to 5 metres deep and 5 kilometres wide.

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Why did mammals survive the 'K/T extinction'?

Picture a dinosaur. Huge, menacing creatures, they ruled the Earth for nearly 200 million years, striking fear with every ground-shaking stride. Yet these great beasts were no match for a 6-mile wide meteor that struck near modern-day Mexico 65 million years ago, incinerating everything in its path. This catastrophic impact -- called the Cretaceous-Tertiary or K/T extinction event -- spelled doom for the dinosaurs and many other species. Some animals, however, including many small mammals, managed to survive.
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