Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Ultra-low oxygen could have triggered die-offs, spurred bird breathing system

31.10.2003


Recent evidence suggests that oxygen levels were suppressed worldwide 175 million to 275 million years ago and fell to precipitously low levels compared with today’s atmosphere, low enough to make breathing the air at sea level feel like respiration at high altitude.

Now, a University of Washington paleontologist theorizes that low oxygen and repeated short but substantial temperature increases because of greenhouse warming sparked two major mass-extinction events, one of which eradicated 90 percent of all species on Earth.

In addition, Peter Ward, a UW professor of biology and Earth and space sciences, believes the conditions spurred the development of an unusual breathing system in some dinosaurs, a group called Saurischian dinosaurs that includes the gigantic brontosaurus. Rather than having a diaphragm to force air in and out of lungs, the Saurischians had lungs attached to a series of thin-walled air sacs that appear to have functioned something like bellows to move air through the body.



Ward, working with UW biologist Raymond Huey and UW radiologist Kevin Conley, believes that breathing system, still found in today’s birds, made the Saurischian dinosaurs better equipped than mammals to survive the harsh conditions in which oxygen content of air at the Earth’s surface was only about half of today’s 21 percent.

"The literature always said that the reason birds had sacs was so they could breathe when they fly. But I don’t know of any brontosaurus that could fly," Ward said. "However, when we considered that birds fly at altitudes where oxygen is significantly lower, we finally put it all together with the fact that the oxygen level at the surface was only 10 percent to 11 percent at the time the dinosaurs evolved.

"That’s the same as trying to breathe at 14,000 feet. If you’ve ever been at 14,000 feet, you know it’s not easy to breathe," he said.

Ward believes the low oxygen and greenhouse conditions caused by high levels of methane from intense volcanic activity are likely culprits in mass extinctions that occurred about 250 million years ago, at the boundary between the Permian and Triassic periods, and about 200 million years ago, at the boundary between the Triassic and Jurassic periods.

The Permian-Triassic extinction is believed to have eradicated 90 percent of all species, including most protomammals, a group of mammal-like reptiles that were the immediate ancestors of true mammals. The Triassic-Jurassic extinction killed more than half the species on Earth, with mammal-like reptiles and true mammals, which evolved during the Triassic Period, hit particularly hard. But dinosaurs, which also evolved between the two extinctions, had little problem with conditions during the Triassic-Jurassic extinction.

"The seminal observation is that dinosaurs skated across the second of these mass extinctions, actually increasing in number as they went along, while everything else was dropping around them," Ward said.

Scientists know of five mass extinction events in Earth’s history, but a cause has been widely agreed upon for only one – the episode at the end of the Cretaceous Period 65 million years ago, when the impact of an asteroid is believed to have brought the demise of the dinosaurs. Such impact also has been suggested as the cause of the Permian-Triassic and Triassic-Jurassic extinctions, but geologists have yet to unearth any indisputable evidence of such an impact, and there is no conclusive evidence of what caused either of the events.

Ward said mass spectrometer readings on fossil material, as well as the extinction pattern for fossils in rock outcrops collected from the time of the two extinctions, indicates the events were drawn-out affairs and did not happen suddenly, as they would have with an asteroid impact.

In addition, he said it is known which types of creatures, and which breathing systems, best survived the extinction events. The same breathing systems are still present in birds, which are known to fare well at high altitudes, where oxygen levels are substantially lower than at the surface.

"The reason the birds developed these systems is that they arose from dinosaurs halfway through the Jurassic Period. They are how the dinosaurs survived," he said.


For more information, contact Ward at (206) 543-2962 or argo@u.washington.edu

Vince Stricherz | EurekAlert!
Further information:
http://www.washington.edu/

More articles from Interdisciplinary Research:

nachricht 36 big data research projects
21.02.2017 | Schweizerischer Nationalfonds SNF

nachricht Coastal wetlands excel at storing carbon
01.02.2017 | University of Maryland

All articles from Interdisciplinary Research >>>

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

Positrons as a new tool for lithium ion battery research: Holes in the electrode

22.02.2017 | Power and Electrical Engineering

New insights into the information processing of motor neurons

22.02.2017 | Life Sciences

Healthy Hiking in Smart Socks

22.02.2017 | Innovative Products

VideoLinks
B2B-VideoLinks
More VideoLinks >>>