"OSTEICHTHYES" (even cladists disagree)
tdib at UMICH.EDU
Wed Sep 22 19:20:36 CDT 1999
Ken Kinman wrote:
> Well, it's gratifying to see the cladists do not agree on this point
>either. Perhaps this is additional evidence that the problems of strict
>cladism has caused a further splintering of cladists into several feuding
>camps. It certainly makes debating them a tricky proposition (no wonder
>these threads are starting to give me a headache).
Debates such as this are not tricky at all within cladistics. They
involve no theory or convoluted logic whatsoever. These debates are
simply resolved on the basis of data.
> On the specific point of "Osteichthyes", my fertile "middle ground"
>seems to lie even between some cladist camps. I informally recognize
>"Osteichthyes" in one of the addenda, but formally only recognize its two
>constituent Classes (Actinopterygea and Sarcopterygea). This approach seems
>to have made at least some of the cladists happy.
What does this mean though? Are actionops and sarcops monophyletic
groups? Do you recognize them as sister-groups? Do you recognize a
monophyletic higher taxon which encompasses the two? Do you call that
Osteichthys? What does your "informal" recognition mean?
> Some cladists seem to
>want to name a lot more nodes than others. Just adds to my impression that
>cladists can be just as arbitrary as eclecticists,
If your claim that we are arbitrary comes down to this, it seems pretty
shallow. The *recognition* of nodes is certainly not arbitrary. It is
only the decision to give the node a name which is done on a purely
heuristic basis. If anyone needs to discuss the node, then give it a
name to ease the conversation. If not, then dont bother. If you find
this too arbitrary, then lets go ahead and name all the nodes. I dont
think that would be the end of the world. We already have over a
million species names; if we name all the nodes on a fully resolved
cladogram of known life, that would only double the number of names we
need to deal with (there being 2n-1 nodes on a fully resolved tree of n
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