[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
Re: Origin of feathers
In a message dated 98-05-04 03:21:48 EDT, TomHopp@aol.com writes:
<< Why did Herrerasurus need to bend its WING OOPS ARM in this
direction, all the way back in the Triassic? Hmmmm. >>
Probably because it was descended from arboreal archosaurs that had already
achieved enough flying ability to require a foldable wing.
The problems with the brooding hypothesis are (1) there is no compelling need
to have the feathers on the arms, particularly since they would interfere with
other useful forelimb functions, such as subduing prey (note the huge claws on
the manus of _Oviraptor_); elongate, movable feathers exclusively for brooding
can appear anywhere on the lateral part of the body; and (2) the hypothesis
doesn't explain other adaptations for flying and arboreal living in theropods,
such as the proximally reduced, retroverted hallux and the stiffened tail,
that don't have anything to do with wings.
But if the feathers are already on the wings for another reason (such as
flying), they can of course easily be exapted for brooding and related
functions (shadowing, display, etc.). Wing feathers -> brooding feathers is
easy, brooding feathers -> wing feathers is very unlikely.