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Re: Transitional Fossils



In a message dated 95-10-02 12:49:43 EDT, martz@holly.ColoState.EDU (Jeffrey
Martz) writes:

>     I don't really understand that argument.  Species that don't evolve 
>into other species go extinct.  I don't think there are any other 
>possible alternatives for a species's fate.  Even if a species is 
>fantastically successful and survives for a long time, it goes out 
>eventually.  I think that saying all species represent leaf nodes is
implying
>
>that new species evolve from nothing.  What do you mean by saying that 
>transitional froms are strictly hypothetical?  Do you mean that the
ancestors
>
>of a organism did not belong to a species itself?   Are you saying that not 
>one single species from the fossil record could have ever given rise to
>another 
>species?  

No, no. That's not what I'm arguing. Of course species evolve into other
species. But _in cladograms_, the taxa being classified are _always_ at the
leaf nodes. The transitional species, which reside precisely on the branches
of the cladogram--not at the leaf nodes--are never explicitly classified:
they are hypothetical. Cladistic analysis cannot discover them. In this
sense, all cladograms are "wrong." What should strike us as odd, therefore,
is that, even when faced with cladograms and their analyses, you still
correctly believe that transitional forms existed (though you are not
necessarily correct in asserting that ALL fossils are transitional).

G.O.