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Re: quantifying bias in the fossil record

At 10:40 AM 5/23/98, Colette H. Adams wrote:
>It has been argued that small dinosaur species were there but are 
>simply missing from the fossil record.  Basically I agree, but 
>there are a number of small mammals from the Mesozoic.  Are many of 
>these species only known from teeth?

By far the vast majority of them are known only from teeth.

Ther are also many known dinosaur teeth, but since dinosaur teeth show less
variation in structure than mammalian teeth, they are less useful
taxonomically - not to mention that they will give an undercount of the
actual diversity.

>  Also, it is curious to me that there are so many passerine
>bird fossils from the late Cenozoic.  Is this because birds are so 
>mobile and fall into more environments that promote fossilization?

Well, and because the LAte Cenozoic is very recent indeed, and there is a
very strong bias in favor of *all* classes of fossils found in sediments
that recent.
>It has also been argued that time removes fossils from the record.

This is pretty well established.  Careful statistical work shows it quite

May the peace of God be with you.         sarima@ix.netcom.com