Re: Pygostyles, Crises,..

[AM Yates <Adam.Yates@bristol.ac.uk>]

On Fri, 21 Jan 2000 Dinogeorge@aol.com wrote:

> In a message dated 1/21/00 3:26:15 AM EST, mickey_mortimer@email.msn.com 
> writes:
> 
> << I'll make a separate data matrix just for you with
>  "flighty" characters deleted.  I'm sure I won't catch all of them, but most
>  things related to flight are easy to see (involving arm and pectoral
>  girdle).  If you or anyone else would like to inform me on flight-related
>  characters not in the pectoral limb or girdle, I'll be glad to consider them
>  as well.  Then I'll run PHYLIP or PAUP (if I have it in time) on the new
>  censored data and see how the results are different from the standard data's
>  results.  If your hypothesis is correct, we'll see secondary flightlessness,
>  if not Aves will only include Archaeopteryx, Rahonavis and pygostylians. >>
> 
> Don't see how this will demonstrate anything. In secondary flightlessness, it 
> is exactly the "flighty characters" that are lost.
> 
Hi everybody,

Its good to be back. For those of you who are interested I am now based
in the UK and I have left the Temnospondyli to begin work on the
Prosauropoda and the evolution of dinosaurian herbivory.

In response to the above message from George: 
 
I think Mickey's experiment is valid. If someone is claiming that we
don't see secondary flightlessness in our parsimony analyses because the
"flighty" characters of volant birds cause them to cluster together
artificially then removing those flighty characters will test this
claim.  If secondary flightlessness is true and it is
the flightly characters that are biasing the total data set then the
volant clade should collapse when the restricted dataset is analysed
cladistically. If it doesn't collapse then the claim that the volants
only cluster together because of flighty characters will have been
falsified.
Note that this experiment only tests the hypothesis that certain
non-volant dinosars are more closely related to modern birds than
Archaeopteryx is (as in Paul's PDOTW). Thus if you beleive that modern
analyses place archaeopteryx in the correct position with respect to
non-volant maniraptoriforms but dispute the node at which flight
actually evolved (which I believe is George's position on the matter)
then the experiment won't mean anything.

cheers

Adam Yates