Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

More than a meteor likely killed dinosaurs 65 million years ago

30.10.2006
Growing evidence shows a series of natural events caused extinction

Growing evidence shows that the dinosaurs and their contemporaries were not wiped out by the famed Chicxulub meteor impact alone, according to a paleontologist who says multiple meteor impacts, massive volcanism in India and climate changes culminated in the end of the Cretaceous Period.

The Chicxulub impact may have been the lesser and earlier of a series of meteor impacts and volcanic eruptions that pounded life on Earth for more than 500,000 years, say Princeton University paleontologist Gerta Keller and her collaborators Thierry Adatte from the University of Neuchatel, Switzerland, and Zsolt Berner and Doris Stueben from Karlsruhe University in Germany.

A final, much larger and still unidentified impact 65.5 million years ago appears to have been the last straw, said Keller, exterminating two-thirds of all species in one of the largest mass extinction events in the history of life. It's that impact - not Chicxulub - that left the famous extraterrestrial iridium layer found in rocks worldwide that marks the impact that finally ended the Age of Reptiles, Keller believes.

"The Chicxulub impact alone could not have caused the mass extinction," said Keller, "because this impact predates the mass extinction."

Keller is scheduled to present that evidence at the annual meeting of the Geological Society of America (GSA) in Philadelphia, on Tuesday, October 24, 2006.

"Chicxulub is one of thousands of impact craters on Earth's surface and in its subsurface," said H. Richard Lane, program director in the National Science Foundation (NSF) Division of Earth Sciences, which funded the research. "The evidence found by Keller and colleagues suggests that there is more to learn about what caused the major extinction event millions of years ago, and the demise of the dinosaurs at the end of the Cretaceous."

Marine sediments drilled from the Chicxulub crater itself, as well as from a site in Texas along the Brazos River and from outcrops in northeastern Mexico, reveal that Chicxulub hit Earth 300,000 years before the mass extinction. Microscopic marine animals were left virtually unscathed, said Keller.

"In all these localities we can analyze their microfossils in the sediments directly above and below the Chicxulub impact layer, and cannot find any significant biotic effect," said Keller. "We cannot attribute any specific extinctions to this impact."

The story that seems to be taking shape, according to Keller, is that Chicxulub, though violent, actually conspired with the prolonged and gigantic volcanic eruptions of the Deccan Flood Basalts in India, as well as with climate change, to nudge species towards the brink. They were then pushed over with a second large meteor impact.

The Deccan volcanism released vast amount of greenhouse gases into the atmosphere over a period of more than a million years leading up to the mass extinction. By the time Chicxulub struck, the oceans were already 3-4 degrees warmer, even at the bottom, Keller said.

"On land it must have been 7-8 degrees warmer," she said. "This greenhouse warming is well-documented. The temperature rise was rapid over about 20,000 years, and it stayed warm for about 100,000 years, then cooled back to normal well before the mass extinction."

Where's the crater? "I wish I knew," said Keller.

Cheryl Dybas | EurekAlert!
Further information:
http://www.nsf.gov

More articles from Earth Sciences:

nachricht Strength of tectonic plates may explain shape of the Tibetan Plateau, study finds
25.07.2017 | University of Illinois at Urbana-Champaign

nachricht NASA flights gauge summer sea ice melt in the Arctic
25.07.2017 | NASA/Goddard Space Flight Center

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Carbon Nanotubes Turn Electrical Current into Light-emitting Quasi-particles

Strong light-matter coupling in these semiconducting tubes may hold the key to electrically pumped lasers

Light-matter quasi-particles can be generated electrically in semiconducting carbon nanotubes. Material scientists and physicists from Heidelberg University...

Im Focus: Flexible proximity sensor creates smart surfaces

Fraunhofer IPA has developed a proximity sensor made from silicone and carbon nanotubes (CNT) which detects objects and determines their position. The materials and printing process used mean that the sensor is extremely flexible, economical and can be used for large surfaces. Industry and research partners can use and further develop this innovation straight away.

At first glance, the proximity sensor appears to be nothing special: a thin, elastic layer of silicone onto which black square surfaces are printed, but these...

Im Focus: 3-D scanning with water

3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects

A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...

Im Focus: Manipulating Electron Spins Without Loss of Information

Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.

For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...

Im Focus: The proton precisely weighted

What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.

To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Closing the Sustainability Circle: Protection of Food with Biobased Materials

21.07.2017 | Event News

»We are bringing Additive Manufacturing to SMEs«

19.07.2017 | Event News

The technology with a feel for feelings

12.07.2017 | Event News

 
Latest News

NASA mission surfs through waves in space to understand space weather

25.07.2017 | Physics and Astronomy

Strength of tectonic plates may explain shape of the Tibetan Plateau, study finds

25.07.2017 | Earth Sciences

The dense vessel network regulates formation of thrombocytes in the bone marrow

25.07.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>