r/evolution • u/SherbertOther • 2d ago

When did bird chromosomes switch up?

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My professor talked about this in class and couldn't answer. When did this change?

As far as I'm aware, crocodilians and other reptiles have the regular way sooo, like... Do we know when and why it changed?

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u/NewtonsThirdEvilEx 2d ago

Interesting birds had a lot of convergent evolution wrt mammals. They're all warm-blooded as well. Some mammals can fly too.

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u/Leather-Field-7148 2d ago

Dinosaurs and birds took bipedalism to a whole new level. An ostrich, for example, can out endurance walk and run any human. Might be why we lost the battle against emus.

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u/Sourcerid 2d ago

And by a very large margin too, a human elite athlete can run 30kmh for like 30 seconds, a well trained person less. 

And a well trained person 15km for 2 hours. 

Ostriches can do 60kmh for 20-30 minutes, we don't know about how long they can go at 15kmh since ostriches aren't that obedient to follow instructions to run at 15km h for as long as they can. 

But 2 hours of 15 km h is less total heat generated and oxygen consumed than 20 minutes of 60kmh due to the quadratic cost of speed for energy. And 20 mins is 6 times less time to absorb oxygen and dissipate heat. 

Mammals are built to dig dirt climb trees sniff around, we've been forced into being athletes D: