astronomy-to-zoology:Why fly?part 2: the ground up hypothesisNow that you known about bird flight an
astronomy-to-zoology:Why fly?part 2: the ground up hypothesisNow that you known about bird flight and the trees down hypothesis. It is now time to talk about the second hypothesis, the ground up hypothesis. The ground up hypothesis states that early birds did not live in the trees but were ground runners, these runners probably used their wings for balance when running and eventually these wings of balance turned into wings that could glide. Some other scientists suggest that wings evolved in an arms races of display as early birds with stronger wings and longer feathers would be more likely to mate. A secondary hypothesis is the WAIR hypothesis. WAIR stands for wing-assisted incline running, during WAIR the bird uses its wings to help the bird quickly run up a steep slope like a tree trunk to help escape a potential predator. However early birds did not have the shoulder muscles needed for this and WAIRs validity is put into question.further readingImage source -- source link