Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Oxygen increase caused mammals to triumph, researchers say

30.09.2005


The first, high resolution continuous record of oxygen concentration in the earth’s atmosphere shows that a sharp rise in oxygen about 50 million years ago gave mammals the evolutionary boost they needed to dominate the planet, according to Paul Falkowski, Rutgers professor of marine science and lead author of a paper published Sept. 30 in the journal Science.

Falkowski and his colleagues have measured the abundance of carbon 13, a byproduct of photosynthesis, in deep-sea core samples that go back 205 million years. Because photosynthesis produces oxygen and leaves carbon 13 behind, the presence of carbon 13 in the fossil samples allows scientists to estimate precisely how much oxygen was in the atmosphere at any given time, Falkowski says.

From a steady 10 percent – the level at which dinosaurs flourished – the oxygen percentage rose to 17 percent 50 million years ago and then to 23 percent by 40 million years ago.



"In the fossil record, we see that see that this rise in oxygen content corresponds exactly to a really rapid rise of large, placental mammals," Falkowski says. "The more oxygen, the bigger the mammals. We argue that the rise in oxygen content allowed mammals to become very, very large – mammals like 12-foot-tall sloths and huge saber-toothed cats. They paved the way for all subsequent large mammals, including ourselves."

The results described in Falkowski’s article, "The Rise of Oxygen Over the Past 205 Million Years and the Evolution of Large Placental Mammals," stem from years of analysis of organic and inorganic core samples. Scientists have been using deep-sea core samples for years, but Falkowski and his colleagues have achieved greater precision in their measurements, thanks to two high-precision, isotope ratio mass spectrometers housed in the geological sciences department at Rutgers.

There were placental mammals on Earth at the time of the great extinction of dinosaurs about 65 million years ago, Falkowski says. They were, however, tiny, limited creatures; the extinction event itself, while eliminating the dinosaurs, did little to further the mammalian domination of the planet. It was the subsequent spreading of shallow seas, the increase in plant life – and photosynthesis – in addition to the consequent increase in oxygen content that gave the mammals the boost they needed, according to Falkowski.

In the last 10 million years, the percentage of oxygen in the earth’s atmosphere has decreased to 21 percent. Falkowski says many scientists believed that great fires burned over the earth about 10 million years ago, reducing the number of trees and, therefore, the amount of photosynthesis and oxygen.

Ken Branson | EurekAlert!
Further information:
http://www.rutgers.edu

More articles from Earth Sciences:

nachricht Predicting unpredictability: Information theory offers new way to read ice cores
07.12.2016 | Santa Fe Institute

nachricht Sea ice hit record lows in November
07.12.2016 | University of Colorado at Boulder

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>