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 Impacts of mass coral die-off on Indian Ocean reefs revealed
21.02.2017 | University of Exeter

nachricht How much biomass grows in the savannah?
16.02.2017 | Friedrich-Schiller-Universität Jena

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Impacts of mass coral die-off on Indian Ocean reefs revealed

21.02.2017 | Earth Sciences

Novel breast tomosynthesis technique reduces screening recall rate

21.02.2017 | Medical Engineering

Use your Voice – and Smart Homes will “LISTEN”

21.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>