[Taxacom] Reptilia (and Hominidae)

Neil Bell neil.bell at helsinki.fi
Tue Mar 17 12:01:57 CDT 2009

I think it's odd that in all of this lengthy and interesting discussion 
about monophyly vs. paraphyly in classifications no-one has mentioned 
rank. Isn't rank clearly the issue, rather than monophyly vs. paraphyly? 
Nearly all of the cited cases of evolutionary information being "lost" 
in monophyletic classifications are where a highly distinctive 
monophyletic group is derived from within another monophyletic group, 
the remaining members of which are recognisable by possession of a suite 
of plesiomorphic characters and have traditionally been recognised as a 
taxon. Clearly the ideal solution is to name the larger group (including 
the derived clade), and to also name the derived clade, without then 
being required to name the otherwise unremarkable sister group of the 
derived clade (and probably other groups as well) because the larger and 
smaller groups are of different rank. I just don't get what evolutionary 
(as opposed to cultural/historical)  information is "lost" by not naming 
the paraphyletic residue of the larger clade. After all, few people are 
suddenly going to find themselves unable to recognise (or refer to) a 
great ape that isn't a human, or a reptile that isn't a bird, just 
because these paraphyletic groups are no longer named. The very fact 
that the paraphyly of the traditional group is not immediately obvious 
from looking at it ensures that it will continue to be recognisable as a 
group to anyone who wishes to see it. If a classification does not 
reflect the fact that birds are, actually, birdy reptiles however, then 
it genuinely is deficient in representing and communicating evolutionary 
information. Of course taxonomic stability is a different problem; the 
ideal solution isn't necessarily practical to implement in a given time 

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