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Re: Feather origin hypothesis (for predator evasion??)
Aerodynamics would have been the last of the major exaptations and
come much later. Filamentous proto-feathers would have more effectively
covered the end of the tail the longer they got. Some predators wouldn't
even get the tail tip, but a mouthful of filaments. And if the filaments
became barbed at an early stage, it might have also been painful enough that
predators would avoid these forms and just go after the naked-tailed forms
(who would then be relatively unfit compared to their filamented relatives).
Exaptation for brooding would have encouraged a more feather-like
structure and also spreading from the tail to the rump and perhaps belly,
and the display function may have developed concurrently (nice brood
protofeathers would probably attract mates as brooding became more
important). Uses for camouflage could have developed as well.
Exaptation for insulation would encourage spread of the feathers
anteriorly, and once the aerodynamic functions on the arms finally kicked
in, they would have a feathered tail rudder already in place. Once gliding
began, powered-flight was just a matter of time as feathers became anchored
more firmly to the bones.
Anyway, don't be too surprised if we find small Triassic Eoraptor-like
forms with just the tail (and perhaps adjacent areas) with protofeathers.
If the insulation phase came in the Upper Triassic, that may have helped
weed out a lot of less insulated relatives during the Triassic-Jurassic
----- Time will tell, Ken
P.S. Looking forward to see how the ideas in Tom Hopp's paper on brooding
might fit in with such a scenario. Anyway, I think tail and rump brooding
could have come first, and wing brooding later on.
From: "ptnorton" <email@example.com>
To: <firstname.lastname@example.org>, <email@example.com>
Subject: Re: Feather origin hypothesis (for predator evasion??)
Date: Thu, 21 Jun 2001 20:08:36 -0400
>The longer the initial hair-like protofeathers got the more effective
would have become.<
If you mean they would have more effective aerodynamically, I think this
would be true only if they were becoming more securely anchored to the
musculoskeletal structure of the animal at the same time.
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