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Re: Fossil Discovery Threatens Theory of Birds' Evolution



In a message dated 6/25/00 8:13:10 PM, ornstn@home.com writes:

<< Cuttlefish are a sort of squid, or at least a member of the Decapoda.  The 
shell of Spirula bears some resemblance to that of an ammonite but is 
hardly "exactly" like one (for example, it does not have the extremely 
complex folding of the septa that is very much a distinguishing feature of 
ammonites). Anyway its spiral shape is a pretty basic one in nature, and 
ammonites and spirula belong in the same class anyway, so the convergence 
involved seems to me interesting but not all that remarkable.  Anyway, I 
still do not see the relevance of your point in bringing it up. >>

Just to show that convergance of the kind I've talked about is indeed a 
possiblilty. That is relevent. BTW. If cuttlefish are squids, so are octopi. 
If they are the same class anyway, which they indeed are, and the convergence 
involved seems "interesting but not all that remarkable," which is also the 
case, then convergence between two anmiotes, which are the same superclass, 
shouldn't be either.

<<>The graphotite-like colonies we've both mentioned is another example of 
such
>convergance. I've never said that these look anything like theropods as you
>seem to be saying. Can nearly exact duplicates evolve completely seperately?

Um... I didn't say that either, and the term is "graptolite".  And what are 
graptolites supposed to be convergent to?>>

Okay, it's a thingie that was found near New Guinea a decade or so back. 
There was a possibility of a ghost lineage of four hundred million years if 
it wasn't convergance.

eric l.