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Re: Who says dromaeosaurs can't fly?



In a message dated 9/13/02 2:34:45 PM Eastern Daylight Time, 
TiJaWi@agron.iastate.edu writes:

> I would query this analogy.  In the secretary bird (_Sagittarius
>  serpentarius_) the greater length of the legs relative to the wings is due
>  principally to the extraordinary elongation of the distal hindlimb.  This
>  bird spends most of its waking hours walking on the ground, stalking
>  terrestrial prey.  As a neornithine bird, the femur is largely decoupled
>  from stride generation, and so it falls to the distal hindlimb elements to
>  provide the bird with an elevated sensory platform.

True; however, the sec'y bird and _Cryptovolans_ may be comparable in more 
general terms, since the latter's legs are still very long.  Incidentally, if 
_Crypto_ did fly, my (uneducated) guess would be that the elongated tibial 
feathers could well have been some sort of fairing to reduce the air 
resistance of the elongated hindlimbs (as I think might be the case in modern 
raptors that extend their legs for prey capture).

As to whether cladistics is capable of capturing neoflightlessness in 
eumaniraptorans, consider this:  we know how to calculate the orbit of a 
celestial body based on observations of its position.  But if we try to do 
the extrapolation based on too few data, we will very likely get it wrong.  
However, this is not necessarily the fault of the methods used to do the 
extrapolation; there just isn't enough information to do it accurately.

Similarly, cladistics does the best it can based on the information at hand.  
Later studies using more data may overturn the results of earlier studies 
using fewer data, but that does not in itself mean that the method is flawed. 
 It may well be that given enough information about enough maniraptoran taxa, 
future cladistic studies will indicate that many or all maniraptorans are 
secondarily flightless.  Will that somehow make cladistics more valid in the 
eyes of those who currently decry it?

--Nick P.

--Nick P.