Asteroid Smashup May Have Wiped out the Dinosaurs

Asteroid Smashup May Have Wiped Out the Dinosa... http://www.sciam.com/article.cfm?articleID=D75F...

CURRENT ISSUE ASK THE HIGHLIGHTS: EXPERTS: The Trouble with Floyd Landis Men tested positive Ending Malaria for increased Deaths in Africa testosterone on the day of his spectacular SEARCH stage win at the Tour de France last year, after testing negative on previous days. Can a large dose of the hormone produce such an immediate and profound improvement? Technology Space & Physics Health Mind Nature Biology Archaeology & Paleontology News Video Blog In Focus Ask the Experts Weird Science Podcasts Gallery Recreations Magazine SA Digital Subscribe Store September 18, 2007 Current Magazine Scientific Ame rican Issue Content Scientific American News Past Feature ArticleDigitals September 05, 2007 Free Newsletters enter e-mail Issues Insights Scientific American Order M Ionsnt oPovpautliaorns RMeilnatded Links Latest News Issues D i dT theec Dhinno iDciea-Oliftf iMeaske Room for Mammals? Asteroid Smashup May Hav Seub scribe D e Reperv Imiepawcts Renew Staking Claims Lone Offender Killed the Dinosaurs Wiped Out the Dinosaurs Give a gift Skeptic Change AVindtei oG Nreawvsit y Submit your videos > Address Sustainable Simulations point to an asteroid collision that sealed the Customer B i rd D flue svprealdoinpgments dinosaurs' fate before their reign was half over Care F l oForumod devastation in East Africa By JR Minkel About Us S m SallA fa rm in the Big Apple MPaleayrssiapnse tcratiniv foer space shot E-mail Print RSS StumbleIt D o gLgey dteterrinrgs-do m o5re0 >, 100 & 150 The rock that blasted a Years Ago 110-mile-wide crater in Mexico's B rNeaekwinsg S Sccaiennce News from Reuters Yucatán Peninsula and probably By the Updated today at 3:18 killed off the dinosaurs 65 million Numbers AM years ago may owe its origin to the N o Wkia osaryksi nITgC starts Qualcomm inKvensotigwatiloendge breakup of an asteroid nearly as big IBM to offer free word processing, as the crater itself. office software Facebook backers create $10 mln fund Using computer simulations, for start-ups China confirms bird flu, says food researchers reconstructed the supplies safe trajectories of several thousand China confirms bird flu outbreak asteroids between Mars and Jupiter CORRECTED: China confirms bird flu that are clustered near a outbreak 25-mile-wide rock called 298 Bone drug cuts death after hip Baptistina. fractures: study Sprint to upgrade Microsoft mobile search services Image: © 2007 SOUTHWEST Adobe says software not fully tested on RESEARCH INSTITUTE new Mac OS AOL to test personal pictures, video, DINOSAUR KILLER: The music site collision of two asteroids [top] China confirms bird flu outbreak in around 160 million years ago Guangdong may have loosed rocks that AMD to sell chip with three electronics slammed into Earth [lower brains

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right], causing the famed K-T Dole recalls bagged salads due to E. coli mass extinction, and the Yahoo to buy Web e-mail maker moon [lower left], leaving the Zimbra for $350 mln crater Tycho. CLICK HERE Western Canadian pine beetle FOR LARGER IMAGE infestation spreads ADVERTISEMENT (article continues below) more > EXCLUSIVE ONLINE ISSUES & SPECIAL EDITIONS The Rise of Nanotech The Early Years Reality-Bending Black Holes

They report that this so-called Baptistina family must have come from the collision of a roughly 40-mile-wide asteroid with one measuring about 110 miles wide—the parent of 298 Baptistina—some 160 million years ago.

The explosion would have showered the space around Earth and the moon with asteroids, doubling the overall rate of Earth and lunar impacts for the next 100 million years or so. Among the shower would hurtle dozens of "dinosaur killer" asteroids six miles wider or larger, approximately one of which should have struck Earth, according to results published in Nature.

"The one crater that sticks out is the Chicxulub Crater," says William Bottke, assistant director of space studies at the Southwest Research Institutein Boulder, Colo., and lead author of the Nature report describing the findings.

Many researchers believe that whatever meteorite or comet punched out the crater in the southern tip of Mexico probably flung up a cloud of dust that killed 75 percent or more of plant and animal species, including the dinosaurs, by choking off the sunlight that supports the food chain. The die-off, known as the K-T extinction, was the biggest mass extinction of the last 250 million years.

Bolstering their statistical argument, Bottke and his colleagues cite ground-based chemical scans of 298 Baptistina that indicate it consists of a substance similar to carbonaceous chondrite, a rare material found in some asteroids.

"This is front page news," say geologists Philippe Claeys and Steven Goderis, both at Vrije University in Brussels, in an editorial accompanying the paper, "as a [six-mile-] sized carbonaceous chondrite is most probably the projectile that formed the Chicxulub Crater." Image: © 2007 SOUTHWEST RESEARCH INSTITUTE The chondrite, which is rich in water and carbon compounds, NEWS FROM OUR PARTNER STEP-BY-STEP MASS cropped up in samples dug from EXTINCTION: An alternate beneath Chicxulub. However, depiction of the collision (A) Bottke and colleagues note that it

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Silent Seizures May Cause Alzheimer's Dementia and breakup (B) of two turns up in fewer than 30 percent asteroids, the drift of their of the usual assortment of Fetal Neurons Still Operate in Adult Brain fragments (C) and the near-Earth asteroids and resulting impacts with the comets—the other possible source Sponsors of a dinosaur killer. moon (D) and Earth (E). PERFECTION IS STARING YOU IN THE FACE CLICK HERE FOR LARGER Pristine, unblemished and untouched by human Based on the estimated frequency hands. 2007 United States Mint Proof Set® IMAGE http://www.usmint.gov/ of Earth impacts from such objects, his group concluded there is more than a 90 percent See your ad here likelihood that the Chicxulub Crater resulted instead from the Baptistina hail.

The researchers say the same bombardment may also have blasted the 53-mile-wide lunar crater Tycho, formed about 109 million years ago during the shower's calculated peak.

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