The Suffocating Age

The Suffocating Age

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.

Two species greeting each other, separated by epochs. Homo sapien and T. Rex



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 clash of the smartest creature on Earth in the Paleozoic era, the cynodont (right), and the apex predator of its time (left), the largest vertebrate top carnivore: the gorgon. Both were reptiles, but the cynodont's descendents went on through much climatic change to deliver an erect, biped--the human mammals.


"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.



Credit: NASA CERES Project /

"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," said paleontologist Peter Ward , co-author of the book Rare Earth.

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.




Related Web Pages

Great Debate Series
The Search for Life in the Universe
Lord of Gondwanaland