About how many areas are you speaking of here? I only know of a handful.
I do not
>remember whether other phyla are definitely known from the pre-trilobite
>basal Cambrian, though there are now some summary papers on the subject.
>
>However, if nothing of certain affinity is found below the trilobites, then
>nothing is known about when taxa appeared and we cannot say whether the
>trilobites appeared before, after, or simultaneously with the lobopods
>except by extrapolation.
It is no extrapolation on my part to say that based on presently available
evidence, the trilobites appear in the record before their putative
ancestors. That was what this thread was about!
Art
http://biology.swau.edu