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Jaime and others,
Michael Benton certainly believes birds are descendants of dinosaurs
(non-avian), as do I, but as we have discussed, this is not same thing as
saying they ARE dinosaurs.
The view that cladists are just "clarifying" what constitutes
"Dinosauria" by including birds is not correct in a broader historical
context. Before the cladists came along, biologists strove to find
monophyletic groups in the old sense of the word (holophyletic and
paraphyletic). What mattered was that a group have a common ancestor, and
it was acceptable to create paraphyletic groups.
Darwin not only said that natural groups should have a common
ancestor, but in his own words (in eloquent 19th Century prose) said that if
modification in sister lineages occurred at greatly different rates that the
more modified lineage should be given a higher taxonomic rank. Cladists
flatly ignore this when they quote Darwin.
Therefore to say that these 19th Century naturalists thought that
Dinosauria had to include all of the descendants of the common ancestor is
reading something into it that simply isn't there.
Dinosauria and Aves were classified separately for well over a
century, even by those who thought birds were probably dinosaur descendants.
Even Michael Benton in his recent Vertebrate Paleontology book classifies
them in separate taxa, although he did put a cross-referencing marker
(functionally similar to those I use) to show that birds are descendants of
P.S. If you want, I can try to finds one of Darwin's two passages which
shows that he believes when sister groups evolve at greatly differing rates
that the faster evolving group should be ranked higher in the taxonomic
hierarchy. And I wasn't going to mention this, but your comments show
that it needs to be brought up. Cladists not only commandeered the taxon
Dinosauria (however they might try to justify broadening its scope), but
they also greatly changed the meaning of the term monophyletic, from
"holophyletic or paraphyletic" to holophyletic only. In fact it was this
move that prompted Peter Ashlock to proposed the term holophyletic in order
to clarify the situation. But the cladists would have none of it, no matter
how much confusion resulted. The ends supposedly would justify the means,
but unfortunately 30 years later it still hasn't ended the way they thought
it would. We are still no closer to the stability they thought would result
from cladistic classification methods, and in some ways it has made matters
worse. Predictions that cladistic stability is just around the corner just
don't wash any more.
I have no more time for trying to explain all this. I'm tired of
spinning my wheels and have other things to do, so this will be the last
time I spend this much effort on such threads within this newsgroup. There
are obviously great philosophical differences between cladists and
eclecticists, and if I haven't made any headway here to convince you that
middle ground approaches are possible (and preferable) then I guess I'm
wasting your time as well as mine.
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