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Re: rarity of bird fossils



In a message dated 95-12-06 12:47:00 EST, swf@ElSegundoCA.ATTGIS.COM (Stan
Friesen) writes:

>Personally, I believe that by the end of the Cretaceous avian
>diversity was approaching modern non-passerine diversity levels.
>
>The problem, of course, is it is hard to argue from lack of data!
>That we have but a small portion of avian diversity is clear, but
>what the real diversity was is really hard to say with any certainty.
>
>

You can get something of a handle on the problem by looking at the
morphological spread among the known forms. For centuries, pre-cladistic
paleornithologists had, for all practical purposes, been placing each new
fossil bird in its own avian order on description. It made for a lot of
monotypic and oligotypic orders! Now cladistic paleornithologists give us
loads of monogeneric stem taxa instead. Same idea, same reason.