>> Look at spirula and
graphitites, I know that neither is a vertebrate, but both evolved to look
exactly like another group.<<
I am not sure what this means. Spirula is a cephalopod that looks like a
squid because it is one, or a close relative of one; coiled shells are
cetrainly not unknown in cephalopods either, though Spirula is the only one
with an internal coiled shell of which I am aware. I am not sure what
"graphiphites" are but if you mean graptolites, they are apparently close
relatives of the living acorn worms, which are somewhat distant relatives
of chordates; a living acorn worm group, the pseudobranchs, has one species
which produces quite graptolite-like colonies and was even considered to be
a living graptolite by its discoverer. I am not sure what else you think
these animals resemble. Certainly neither Spirula nor graptolites look
like any vertebrate.
--
Ronald I. Orenstein Phone: (905) 820-7886
International Wildlife Coalition Fax/Modem: (905) 569-0116
1825 Shady Creek Court
Mississauga, Ontario, Canada L5L 3W2 mailto:ornstn@home.com