Re: New alvarezsaurid

["Matthew Troutman" <m_troutman@hotmail.com>]

> Anything that allows an animal to control its motion while
>airborne, no matter how slightly, becomes a flight characteristic or 
>feature.

   I guess it just depends on your definition of flight. Me, I would say 
that anything that allows an animal to control itself during gliding or 
parachuting is a gliding or parachuting adaptation.

>Flapping flight is a specialized form of flight that evidently appeared 
late
>in the evolution of birds well after numerous flight features had 
already
>evolved--indeed, it's not yet clear whether _Archaeopteryx_ itself was 
a
>flapping flier. I would certainly agree that many flight adaptations 
evolved
>for reasons other than flapping flight; but I would tend to disagree 
that they
>evolved for reasons other than flight (for the most part), as I have 
described
>it.

    Why would it appear that flapping flight is a characteristic that 
evolved late in bird evolution? 

I think that it is quite clear that Archaeopteryx was a flapping flier. 
It has characteristics that are only seen in volant, flapping birds:

1) Assymetric flight feathers.
2) Curved remiges.
3) Ventral furrow on the shaft of the flight feathers. 
4) Hypertrophied furcula that has not degenerated or formed an obtuse 
angle.
5) Elongate coracoid that faces posteriorly. 
6) Heart-shaped ulnarae.


Basically I think that volant adaptations must have evolved for reasons 
other than flight for flight to evolve and only after flight has evolved 
have some of the more advanced flight features evolved (strut-like 
coracoid for example).

MattTroutman

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