Real taxa => Ranking

[christian thompson]

I was surprise to read:

How to select the "appropriated" taxonomical rank (genera, tribe etc)
for a
group is a matter of debate, mainly because this issue is out of the
scope
of the formal methods of systematics (cladistics).

====================

When Willi Hennig himself clear proposed an objective method of ranking
years ago as part of his "Phylogenetic Systematics" [= ? cladistics at
one time, but today Willi would not recognize what we are calling
"cladistics" has having any relationship to his idea, etc.]

Hennig simply stated the proper criterion for rank was age of the
taxon. And he suggested once one had their preferred cladistic
hypothesis / tree, then there were various other methods which then
could be used to date the taxa within the hypothsis / tree. He suggested
various date for the categories of the Linnaean hierarchy, like 100 MYA
or late cretaceous origin for the family category.

Obviously Huxley who placed Homo sapiens in the Kingdom Psychozoa
objected as did virtually everyone else. And apparently after that all
was forgotten, but ...

So, objective methods of ranking are only "out of the scope of the
formal methods of systematics (cladistics)" for those who do not want
them.

Oh, well ...



F. Christian Thompson
Systematic Entomology Lab., USDA
c/o Smithsonian Institution
MRC-0169 NHB
PO Box 37012
Washington, DC 20013-7012
(202) 382-1800 voice
(202) 786-9422 FAX
cthompso at sel.barc.usda.gov e-mail
www.diptera.org  web site