* Astronomy

Blobrana · L

RE: Dinosaur extinction

Blobrana · L

Scientists determine most precise dates yet for dinosaur extinction 66 million years ago

The demise of the dinosaurs has been called the world's ultimate whodunit.
Was the cause a comet or an asteroid impact? Volcanic eruptions? Climate change?
In an attempt to resolve the issue, scientists at the Berkeley Geochronology Center (BGC) at the University of California, Berkeley, and at universities in the Netherlands and the United Kingdom, have determined that an impact event occurred at about the same time as the mass extinction of the dinosaurs.
Using a recalibrated technique for dating Earth minerals, the researchers hypothesize that impact happened 66,038,000 years ago, and that it produced the final atmospheric conditions needed to wipe out the dinosaurs.
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Blobrana · L

Ancient ecosystem's vulnerability to catastrophe contributed to dinosaur extinction

A mass extinction about 65 million years ago wiped out numerous species, most famously the dinosaurs, but a new study finds that latent vulnerabilities in the structure of North American ecosystems made the extinction worse than it might have been.
Researchers at the University of Chicago, the California Academy of Sciences and the Field Museum of Natural History published their findings Oct. 29 in the online issue of the Proceedings of the National Academy of Sciences.
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Blobrana · L

Dinosaur die out might have been second of two closely timed extinctions

The most-studied mass extinction in Earth history happened 65 million years ago and is widely thought to have wiped out the dinosaurs. New University of Washington research indicates that a separate extinction came shortly before that, triggered by volcanic eruptions that warmed the planet and killed life on the ocean floor.
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Blobrana · L

Drilling for dinosaur death: the Joides Resolution finds extinction in deep sea mud

Finding K-T boundary core was one of the most exciting moment's we've had so far! It was perfect. We could see a layer of blackish-green gritty material that the asteroid impact ejected into the atmosphere, which then rained down into the ocean. There was an abrupt change from light grayish sediment, rich in the white calcium carbonate shells of fossil plankton, to brown sediment devoid of calcium carbonate plankton fossils. Many members of our science party posed for pictures with the K-T, our very own celebrity sediment core. Even though the K-T core was amazing, our primary objective is to learn about the climate events that occurred after 65 million years ago.
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Blobrana · L

Dinosaurs may have been on the road to extinction before an asteroid crashed into Earth and finished the job, researchers claim.

The asteroid collision is widely believed to have directly caused the disappearance of non-avian dinosaurs 65 million years ago, but some palaeontologists have suggested they may already have been in decline.
Now a study of the remains of 150 different species suggests some groups of large herbivores began on the road to extinction 12 million years before the end of the Cretaceous period, when the asteroid struck.
Hadrosaurs, a large group of duck-billed dinosaurs, and Ceratopsids, a group which includes the Triceratops, were already displaying "warning signs" of impending extinction, researchers found.
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Blobrana · L

Horizon: What Really Killed The Dinosaurs

Until recently most scientists thought they knew what killed off the dinosaurs. A 10km-wide meteorite had smashed into the Yucatan peninsula in Mexico, causing worldwide forest fires, tsunamis several kilometres high, and an 'impact winter' - in which dust blocked out the sun for months or years. It was thought that the dinosaurs were blasted, roasted and frozen to death, in that order.
But now a small but vociferous group of scientists believes there is increasing evidence that this 'impact' theory could be wrong. That suggestion has generated one of the bitterest scientific rows of recent times.

Blobrana · L

Massive volcanoes, meteorite impacts delivered one-two death punch to dinosaurs

A cosmic one-two punch of colossal volcanic eruptions and meteorite strikes likely caused the mass-extinction event at the end of the Cretaceous period that is famous for killing the dinosaurs 65 million years ago, according to two Princeton University reports that reject the prevailing theory that the extinction was caused by a single large meteorite.
Princeton-led researchers found that a trail of dead plankton spanning half a million years provides a timeline that links the mass extinction to large-scale eruptions of the Deccan Traps, a primeval volcanic range in western India that was once three-times larger than France. A second Princeton-based group uncovered traces of a meteorite close to the Deccan Traps that may have been one of a series to strike the Earth around the time of the mass extinction, possibly wiping out the few species that remained after thousands of years of volcanic activity.
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Blobrana · L

New clues into mass dinosaur extinction

To test an alternative theory explaining the 65-million-year-old mass extinction that led to the demise of the dinosaurs, Princeton University researchers developed a model that more accurately accounts for the Earth's heterogeneities and offers different interpretations from previous models.
The researchers, who were based in the lab of geoscience and applied and computational mathematics professor Jeroen Tromp GS '92, focused on a theory that explained the mass extinction as the result of a long volcanic eruption triggered by a meteorite strike near Chicxulub on Mexico's Yucatan Peninsula. This theory suggested that the strike could trigger volcanic activity on the opposite side of the globe.
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Blobrana · L

Did the dinosaurs go out with a bang or a whimper?
The question is one of the most hotly contested in palaeontology and revolves around an apparent gap in the fossil record immediately prior to the K-T boundary - the distinct layer of geological sediments separating the Cretaceous and Tertiary periods, and associated with a massive asteroid impact and global extinction event.
Rocks laid down at the time - some 65.5 million years ago - show a thin layer abundant in rare elements like Iridium, spherules and shocked Quartz that could only have come from a meteorite impact.
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