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Re: Fw: Dinosaurs and birds



Don Ohmes wrote:

But! What about bats and pteros? I mean, pteros and bats? No handy feathers there.

Pterosaurs and bats are assumed to have evolved from patagial gliders. Unfortunately there is no direct evidence of what the incipient flight apparatus of basal pterosauromorphs or basal "panchiropterans" may have looked like. However, in pteros and bats both the forelimbs and hindlimbs were/are incorporated into a continuous flight surface, which suggests that they evolved from quadrupedal gliders that had this same arrangement.


Birds, on the other hand, evolved from terrestrial bipeds. Even though maniraptoran theropods may have passed through some kind of facultatively arboreal quadruped stage on the way to flight, their morphology essentially remained that of a biped. Also, the initial stages of the evolution of flight might have evolved on the ground, so many scenarios hypothesize that incipient wings first evolved in terrestrial theropods.

Still, pterosaurs might have evolved from bipeds, especially if pterosaurs are avemetatarsalians. I don't know much about the (undescribed) archosaurs from Texas that have been interpreted as basal pterosauromorphs ("Pteromimidae"). Such as if they shed any light on the origin of pterosaur flight, for example.

Cheers

Tim

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