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Re: flying Archie

Mike Keesey wrote:

Why does selective pressure need to be invoked? This is the earliest known winged theropod, and it's probably not too far removed, chronologically, from the very first ones. Long tails are just the ancestral state--perhaps there had not been enough time to "evolve out of them".

Two reasons:

(1) There was "enough time" for the line leading to_Archaeopteryx_ to evolve a thoroughly modern plumage. The evolution of the integument occurred a lot faster than that of the skeleton. One possible explanation (hypothesis) is that selection favored the retention of the coelurosaurian body plan in the line leading to _Archaeopteryx_ (and beyond - see (2)). If _Archaeopteryx_ had been found without feathers, I'm pretty sure that nobody would have recognized it as a bird (something Ostrom frequently drew attention to).

(2) Long tails (by avian standards) persisted beyond the Late Jurassic, and are even kept by at least one Late Cretaceous bird: _Rahonavis_. This tells me that some avian lineages were in no hurry to shorten the tail, meaning that there was an advantage in retaining a long tail - such as for their *particular* aerial locomotor style.

(And, actually, _Archaeopteryx_' tail is rather reduced compared to
other theropods of the time.)

But not compared to some other later theropods that (based on most current analyses) are more distantly related to modern birds - including oviraptorosaurs and therizinosaurs. Late Jurassic oviraptoriforms may have had shorter tails than _Archaeopteryx_ - we just don't have enough material from these critters to know their overall proportions.