Oct
13
2005

Scientists at Rutgers University in New Jersey have discovered that the amount of oxygen in the Earth's atmosphere has more than doubled over the last 205 million years.

By studying samples of seafloor material going back millions of years, they determined that the atmosphere was only 10% oxygen during the time of the dinosaurs. It rose as high as 23% by 40 million years ago. (The air is 21% oxygen today.) That's about the time that really large mammals, like elephants and rhinos, started to emerge.

Oxygen levels may have affected the evolution of mammals. These warm-blooded creatures need three to six times as much oxygen as a reptile of the same size. The lack of oxygen may have prevented them from growing very large. But as oxygen levels increased, mammals could start getting bigger.

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Anonymous's picture
Anonymous says:

cool!!!

posted on Tue, 11/01/2005 - 1:16pm

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