Oxygen in Ancient Atmosphere Rose Gradually To Modern Levels
College Park MD (SPX) Dec 03, 2005
The history of life on Earth is closely linked to the appearance of oxygen in the atmosphere. The current scientific consensus holds that significant amounts of oxygen first appeared in Earth's atmosphere some 2.4 billion years ago, with a second large increase in atmospheric oxygen occurring much later, perhaps around 600 million years ago.
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Early Earth Likely Had Livable Continents
Boulder CO (SPX) Nov 18, 2005
A surprising new study by an international team of researchers has concluded Earth's continents most likely were in place soon after the planet was formed, overturning a long-held theory that the early planet was either moon-like or dominated by oceans.
NASA Scientists Confirm Toxic Seas During Earth's Evolution
Washington DC (SPX) Oct 07, 2005
NASA exobiology researchers confirmed Earth's oceans were once rich in sulfides that would prevent advanced life forms, such as fish and mammals, from thriving. The research was funded in part by NASA's exobiology program.
Study Casts Doubt On 'Snowball Earth' Theory
Washington DC (SPX) Sep 30, 2005
A study that applied innovative techniques to previously unexamined rock formations has turned up strong evidence on the "Slushball Earth" side of a decades-long scientific argument.
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Calculations Favor Reducing Atmopshere For Early Earth
St Louis MO (SPX) Sep 08, 2005
Using primitive meteorites called chondrites as their models, earth and planetary scientists at Washington University in St. Louis have performed outgassing calculations and shown that the early Earth's atmosphere was a reducing one, chock full of methane, ammonia, hydrogen and water vapor.
Climate Model Links Higher Temperatures to Prehistoric Extinction
Boulder CO (SPX) Aug 25, 2005
Scientists at the National Center for Atmospheric Research (NCAR) have created a computer simulation showing Earth's climate in unprecedented detail at the time of the greatest mass extinction in the planet's history.
Meteor Impacts: Life's Jump Starter?
Devon Island, Canada (SPX) Aug 09, 2005
Meteor impacts are generally regarded as monstrous killers and one of the causes of mass extinctions throughout the history of life. But there is a chance the heavy bombardment of Earth by meteors during the planet's youth actually spurred early life on our planet, say Canadian geologists.
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Model Gives Clearer Idea Of How Oxygen Came To Dominate Earth's Atmosphere
Seattle WA (SPX) Aug 09, 2005
A number of hypotheses have been used to explain how free oxygen first accumulated in Earth's atmosphere some 2.4 billion years ago, but a full understanding has proven elusive.
Earth's Surface Transformed By Massive Asteroids
Canberra, Australia (SPX) Aug 08, 2005
A cluster of at least three asteroids between 20 and 50 kilometres across colliding with Earth over 3.2 billion years ago caused a massive change in the structure and composition of the earth's surface, according to new research by ANU earth scientists.
Virtual Trip To The Heart Of 400 Million Years Old Microfossils
Paris, France (SPX) Jul 22, 2005
Researchers from the Universit� de Montpellier II (France), the Institute of Geology of China, and the ESRF have been able to identify enigmatic fossils from Devonian (about 400 million years) as fructification of charophyte algae.
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Researchers Discover Half-Billion Year-Old Fossils
Blacksburg, VA (SPX) Jul 12, 2005
Scientists interested in ancient life have a wealth of fossils and impressions frozen in rocks that they can study from as far back as 540 million years ago � when animals with shells and bones began to become plentiful. But evidence of complex life older than 540 million years is scant and difficult to study.
Evolving Away From Extinction
Berkeley CA (SPX) Jun 27, 2005
The fossilized skeleton of a small crocodile relative excavated last year at Petrified Forest National Park in Arizona throws a wrench into theories of how and where the dinosaurs arose more than 210 million years ago at the end of the Triassic Period.
Extreme Melting Event Defines Earth's Early History
Washington DC (SPX) Jun 20, 2005
Could Earth have had an even more violent infancy than previously imagined? New isotope data suggest that the Earth not only had a very violent beginning but also point to new information about our planet's chemical evolution.
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