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Re: The birds vs. the pterosaurs



Steve Doolittle wrote:
> 
>  Which brings me to this question:  If the dinosaurs evolved into birds, why
> did they do that when that ecological niche was already filled by the
> pterosaurs?

Perhaps because the two groups evolved at the same time. If dinosaurs,
mammals and pterosaurs all seem to appear at roughly the same time
(late-ish Triassic), perhaps this represented an evolutionary explosion
filling the ecological vacuums left by the Late Permian extinctions.
Such evolutionary events seem to occur tens of millions of years after
mass extinctions - around 50 million years ago there seems to have been
a lot of new mammal and plant forms appearing (including the all
important grasses). I wouldn't be surprised if the reason that the
earliest pterosaur fossils appear to be advanced fliers is because they
were competing with another flying form, thus providing the selective
pressure to hurry things along.

(Yes, I've always had a soft [integumentary] spot for BCF)

-- 
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Dann Pigdon                   Australian Dinosaurs:
GIS Archaeologist           http://dannsdinosaurs.terrashare.com
Melbourne, Australia        http://www.alphalink.com.au/~dannj/
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