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Re: Archaeopteryx or Velociraptor



At 05:03 PM 7/8/97 -0400, you wrote:
>Imagine that Velociraptor is a) nonavian (generally agreed on) and b)
>secondarily flightless. In the absence of a volant outgroup to the
>Velociraptor-Neornithe clade, no amount of phylogeny can ever hope to
>demonstrate that it is secondarily flightless. 
>    Imagine for a moment that the world is attempting to decieve us about
>the true workings of evolution (paranoid, yes, but everything is so darn
>complicated that sometimes it seems like a pretty good model...)

Paranoid and (more importantly) antithetical to the very basis of Science!!
Science assumes that nature is not out to decieve us.  (Incidentally, this
is why many scientists can be taken in by pseudoscience charlatans, while
people trained in deception (such as stage magicians) have a better 

>and has
>conspired to eliminate both 
>a) tinamous
>b) all fossils of volant birds from outside the neognath-paleognath split. 
>Pretty simply, you don't have a chance in heck of using a phylogenetic
>bracketing to demonstrate secondary flightlessness in ratites.

And imagine there is an insubstantial invisible pink unicorn in my carport
which cannot be perceived by any form of detection we can develop.

The point being...?

More productively, how would (or even COULD) you demonstrate that the
scenario you propose is more likely than one in which ratites were indeed
secondarily flightless?  Additional data would be needed to resolve this.

Among such data are: a) the missing taxa; b) anatomical features that
*unquestionably* support a volant ancestry for ratites.  Sorry, but this
doesn't cut it with dromaeosaurids, etc.: their anatomical features *might*
have been modified from flight adaptations, but they are also consistant
with non-(pre-)volant predatory or scansorial habits.

>    It may simply be that, as in my speculative example, the current data
>is such that no amount of phylogenization can ever resolve it. 

Yes, the *current data*.  No scientific hypothesis can be better than the
current data.  So what?  As I stated, addition of new data could demonstrate
a flying ancestry for dromaeosaurids, etc.  Until those data are found,
though, such an hypothesis is only speculation.

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:th81@umail.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661