Re: New alvarezsaurid

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

<If some theropods did descend from early birds, then you would expect 
_all_ the diagnostic features still to be present.>

Not if one of those theropods were to inhabit a niche not explored by 
its competitors, and later specializied because of the lack of 
competition, it would occlude any unneccesary features that did not 
maximize the performance in said niche. The kiwi, for instance, lays one 
huge egg, as the two ovaries, whatever (this does not mean it is 
suddenly so wierd it _can't_ be a ratite, all others of which lay more 
than one egg) to increase survival statistics, is small and fast and 
thus can dodge predators two ways, is colored for camouflage, and the 
bill is especially derived from other ratities and tinamous.

Owls are exclusive predators (I'll take *Bubo bubo*, the eagle owl) and 
so are goatsuckers, but owls have feet with the fourth digit reversed, 
in the manner of woodpeckers. This does not make them woodpeckers. They 
developed features, lost them, and became unique, but their still, 
esentially, derived goatsuckers (or goatsuckers are derived owls).

Jaime A. Headden
Qilongia

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