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Re: Exaptation



In a message dated 95-12-07 21:03:26 EST, ornstn@inforamp.net (Ronald
Orenstein) writes:

>>Actually, as the central avian lineage approaches modern birds, the rate of
>>appearance of flightless branches seem to decrease. There were
>>hesperornithiforms, _Patagopteryx_, perhaps alvarezsaurids and avimimids.
>
>This does not seem to fit the facts.  Post-KT flightless birds include the
>various ratites (which may or may not have evolved flightlessness
>independently), penguins, dromornithids, diatrymids, phorusracids, mancallid
>auks, plotopterygids (or whatever these things were called, I forget), and,
>in recent times (though not all at present, alas) flightless cormorants (at
>least two lines), ibises (at least two or three separate lines), ducks
>(several lines), megapodes (as I recall), rails (lots of lines), the Great
>Auk, aptornithids, kagus, parrots (the kakapo), a probably flightless hoopoe
>from St. Helena, and even passerines (the hapless Stephen Island Rockwren of
>New Zealand, exterminated by the lighthouse-keeper's cat).  I see no
>drop-off in the rate of appearance of flightless lineages.

Probably the lousy fossil record fosters the illusion.