Re: New alvarezsaurid

["Jaime Headden" <jaemei@hotmail.com>]

Matt Troutman wrote:

<There would be less convergence if alvarezsaurs were regulated to a 
position in Aves that is above that of Archaeopteryx and even at a 
sister-relationship with ornithurines.>

Yes, I agree. And this is where they should be. This being a good 
cladistic analysis. I'm offering an opposing viewpoint, is all.


<In Aves there is a LOT of convergence, but what this convergence is is 
convergence where you can still trace the direct ancestors or 
sister-groups using many methods. But, to my knowledge, few groups have 
lost the diagnostic features of Aves, they just modified them. Now, if 
oviraptorosaurs are related to the dromaeosaur/avian clade the supposed 
lost characters would appear in a modified form.>

I forgot to mention something, mayber perhaps it's been said so many 
times on the list, I thought I would be redundant to heck if I did say 
it, but we can trace Aves' convergences because we have so much of the 
group (nearly all of them are living, or were living, during our 
timeline when we could study them) and many new fossils of them that are 
clearly birds (*Confuciusornis*, *Protarchaeopteryx*, Archie and 
*Rahona*, etc.) but when dealing with dinos (here's the redundant point) 
we have so _little_ of the fossil record in existence and knowledge that 
to try to trace a set of lineages by convergence as seen in Aves would 
be, well, pardon me, foolish. It can be refuted, is equivocal, and so 
on. I'm not saying it's wrong, though.

<Give me a rebuttal theory of alvarezsaurid evolution, and I'll reflect 
your points.>

<A model of alvarezsaur evolution with view convergences would be if 
they were birds that were above Archaeopteryx. All of the avian 
characters can be explained.>

Because we know so much of it.

<The characters that are shared with oviraptorosaurs can be considered 
as convergences related to the flightness nature of alvarezsaurs and the 
strange, unknown habits of oviraptorosaurs.>

Well, the habits aren't the point. The degree of convergence is also a 
convergent characters, but because the character numbers seem to favor 
an "true" avian *Shuvuuia* as opposed to an oviraptorosaurian one, I 
will say that the evidence is on Archie's side, not Ovi's. Hmmm. Time 
will tell, of course.

(If those fossils were preserved, that is).

Jaime A. Headden

MattTroutman


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