[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Longer Tails in Birds: Functional "Re"Evolution



Mickey Mortimer (mickey_mortimer11@msn.com) wrote:

<<It's less derived than Sapeornis based on- cervical centra not
heterocoelous; absence of pygostyle?.>>

David Marjanovic (david.marjanovic@gmx.at) wrote:

<_Long tail_. And I'd need good evidence to accept a reversal of that,
given the fact that all other known cursorial birds have never reevolved a
sizable tail, even though they could use it.>

  Actually, birds have redeveloped the long tail. It's just formed from
feathers rather than flesh and bone. There would be no need to attempt
some paedomorphic development of the more complete tail when readily
adaptible structure (feathers) are available, and take less energy to
modify. This is why [I think] that birds never re-adapted the bony tail.
It may be no more a simple question than that. Of course, one needs to
observe birds using this in such a manner as would a bipedal lizard in the
same instance ... and voila! we have such cases around us. True, in
hypercursoprial birds like ostriches, there is a very short tail, but this
is true in hypercursorial theropods, too ... reduction of the tail and
elevation of the neck resulting in narrowing the turn radius and allow
greater turning control. Nonetheless, comm ents please?



=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

__________________________________________________
Do You Yahoo!?
Send FREE Valentine eCards with Yahoo! Greetings!
http://greetings.yahoo.com