28 May 2015

Bird Breath

Here's something every schoolkid should know, but very few people have ever even heard about. Despite centuries of study of bird anatomy, it was only really figured out in 2005! Read about it in Ward and Kirshvink, A New History of Life, which I recommend.

Birds (which are, for all practical purposes, saurischian dinosaurs whose last common ancestor with us was about 200 million plus years back) have a vastly superior respiratory system to that of mammals or other (extinct) dinosaurs. Their tracheas go all the way to where our diaphragm would be, and they have air sacs, which fill with air when they breathe. They then push the air through their lungs and out. So it's all one way flow, far more efficient than our in and out breathing. It was originally an adaptation to the low oxygen world of the early Triassic. It enables them to breathe independently of locomotion (mammals have to coordinate their breathing), use less energy to breathe, and survive on lower oxygen levels.

The homologous bones in saurischian dinosaur fossils prove that they too had this system.

Now, I bet you didn't know THAT.

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