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Subject: Re: (intentionally left blank?)
The original title was pygostyle but that mail bounced back.

but I'll yield to the aerodynamic experts on this point! >Nonetheless, I think you could use the pygostyle-bearing oviraptor to >argue the exact opposite of what George is suggesting.

That is exactly was what it my mind. The primitive forms have long tails, the derived ones have pygostyles. Thus unless one forms a sister grouping of Pygostyled birds with Oviraptorosaurs- which would mean many more homoplasies, the pygostyles are convergent. But all the same it is a remarkable convergence. Given the convergences in other forms such as the troodontids and Avimimus there may be some truth in "birdhood" being a likely state due to constraints imposed on the material available for natural selection. It would probably make an interesting thing to compare the regulatory elements of the posterior hox genes in living birds and crocodiles as a start to understand this issue.

I wonder what the animal behind the Protoavis skull was ? definitely a bird convergence?

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