[SWAMPSNIPER]

"birds breathe straight through"? ----------------------

Straight through what?

[Soliton]

According to evolutionary theory, did mammals develop from reptiles, from birds, or from something else?

Birds use a lot of energy and require rapid respiration and smaller alvioli. They have evolve a breathing system like a bagpipe with air storage bags. They breath in and out, but the lungs themselves process the oxygen/ co2 exchange continuously. Dinosaurs breathed the same way. More evidence for evolution.

[Steve Van Doorn]

http://en.wikipedia.org/wiki/Bird_anatomy#Respiratory_system

[LiteKeeper]

Their pulmonary system is a flow-through, rather than in-and-out as we do. This ensures a constant supply of oxygen during flight. For an "in-and-out" breather to become a "flow-through" breather would require some kind of a hole to open up in the system. This is a virtual impossibility.

Dinos breathed like birds?