>At our current point in our search for Cambrian ancestors, however, the lack
>of fossils is due more to a lack of holes (i.e., a lack of regions) rather
>than a lack of marbles. A lack of holes would constitute a true absence of
>evidence -- i.e., a lack of positive evidence that verifies or refutes the
>hypothesis; in other words, negative evidence -- but we cannot say that this
>constitutes evidence of absence because we are lacking the very data we
>would need to make that determination.
On what basis do you figure there is a lack of regions with Precambrian
outcrops? What in your mind constitutes a lack? And exactly what data
would we need to make that determination? A few Precambrian metazoan fossils?
Art
http://geology.swau.edu