Free Newsletters - Space - Defense - Environment - Energy - Solar - Nuclear
..
. 24/7 Space News .




EARLY EARTH
Dinosaur die out might have been second of two closely timed extinctions
by Vince Stricherz
Seattle WA (SPX) Sep 10, 2012


Thomas Tobin clears sand from around the fossil of a giant ammonite he found in 2009 on James Ross Island in Antarctica.

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.

The well-known second event is believed to have been triggered by an asteroid at least 6 miles in diameter slamming into Mexico's Yucatan Peninsula. But new evidence shows that by the time of the asteroid impact, life on the seafloor - mostly species of clams and snails - was already perishing because of the effects of huge volcanic eruptions on the Deccan Plateau in what is now India.

"The eruptions started 300,000 to 200,000 years before the impact, and they may have lasted 100,000 years," said Thomas Tobin, a UW doctoral student in Earth and space sciences.

The eruptions would have filled the atmosphere with fine particles, called aerosols, that initially cooled the planet but, more importantly, they also would have spewed carbon dioxide and other greenhouse gases to produce long-term warming that led to the first of the two mass extinctions.

"The aerosols are active on a year to 10-year time scale, while the carbon dioxide has effects on a scale of hundreds to tens of thousands of years," Tobin said.

During the earlier extinction it was primarily life on the ocean floor that died, in contrast to the later extinction triggered by the asteroid impact, which appeared to kill many more free-swimming species.

"The species in the first event are extinct but the groups are all recognizable things you could find around on a beach today," he said.

Tobin is the lead author of a paper in the journal Palaeogeography, Palaeoclimatology, Palaeoecology that documents results of research conducted in a fossil-rich area on Seymour Island, off the Antarctic Peninsula.

That particular area has very thick sediment deposits and, for a given interval of time, might contain 10 times more sediment as the well-known Hell Creek Formation in Montana. That means scientists have much greater detail as they try to determine what was happening at the time, Tobin said.

The researchers took small surface core samples from rocks and fossils in the Antarctic sediment and used a method called magnetostratigraphy, employing known changes over time in Earth's magnetic field to determine when the fossils were deposited. The thicker sediment allowed dating to be done more precisely.

"I think the evidence we have from this location is indicative of two separate events, and also indicates that warming took place," Tobin said.

There is no direct evidence yet that the first extinction event had any effect on the second, but Tobin believes it is possible that surviving species from the first event were compromised enough that they were unable to survive the long-term environmental effects of the asteroid impact.

"It seems improbable to me that they are completely independent events," he said.

The paper's coauthors are Peter Ward, Tobin's doctoral adviser, and Eric Steig, both UW professors of Earth and space sciences; Eduardo Olivero of the Southern Center for Scientific Research in Argentina; Isaac Hilburn, Matthew Diamond and Joseph Kirschvink of the California Institute of Technology; Ross Mitchell of Yale University; and Timothy Raub of the University of St. Andrews in Scotland.

The work was funded by the National Science Foundation Office of Polar Programs and the National Scientific and Technological Promotion Agency in Argentina.

.


Related Links
University of Washington
Earth and space sciences;
Explore The Early Earth at TerraDaily.com






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





EARLY EARTH
Gardener's delight offers glimpse into the evolution of flowering plants
Seattle WA (SPX) Sep 06, 2012
The Pink Double Dandy peony, the Double Peppermint petunia, the Doubled Strawberry Vanilla lily and nearly all roses are varieties cultivated for their double flowers. The blossoms of these and other such plants are lush with extra petals in place of the parts of the flower needed for sexual reproduction and seed production, meaning double flowers - though beautiful - are mutants and usually ste ... read more


EARLY EARTH
NASA's GRAIL Moon Twins Begin Extended Mission Science

Flags at half mast across US for Armstrong funeral

Walls of Lunar Crater May Hold Patchy Ice, LRO Radar Finds

Russia's moonshot hope 'not a dream'

EARLY EARTH
Indian PM defends spending on space exploration

Hadley Crater - closing in on the Martian interior

Northrop Grumman Aids Navigation of NASA's Curiosity Mars Rover

Mars's dramatic climate variations are driven by the Sun

EARLY EARTH
Mankind's messenger at the final frontier

35 years on, Voyager 'dancing on edge' of outer space

Space-age food served up with seeds of success

Africa eyes joint space agency

EARLY EARTH
Tiangong Orbit Change Signals Likely Date for Shenzhou 10

China Focus: Timeline for China's space research revealed

China eyes next lunar landing as US scales back

China unveils ambitious space projects

EARLY EARTH
Astronauts Take Second Spacewalk

ISS crew complete space station repair

Crew Wraps Up Preparations for Wednesday's Spacewalk

Building MLM Under Way at Khrunichev

EARLY EARTH
Arianespace concurrently manages six missions with Ariane 5 and Soyuz

First-Stage Fuel Loaded; Launch Weather Forecast Improves

NASA launches mission to explore radiation belts

ISRO to score 100 with a cooperative mission Sep 9

EARLY EARTH
Birth of a planet

A Hot Potential Habitable Exoplanet around Gliese 163

NASA's Kepler Discovers Multiple Planets Orbiting a Pair of Stars

How Old are the First Planets?

EARLY EARTH
World watches for 'iPhone 5' unveiling Wednesday

Airborne observatory and electronic noses - DLR presents new space developments at ILA

Estonian first graders to learn computer code

Tough gel stretches to 21 times its length, recoils, and heals itself




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement