RE: Defending grades (Was: Re: Archaeopteryx (rant))

["Tim Williams" <twilliams_alpha@hotmail.com>]

grossber <grossber@grinnell.edu> wrote:

> You people sure are contentious and quite strident considering that there 
> really is no right and wrong.  Look at the best cladogram from 10 years ago 
> versus today.  In 10 years from now, expect even more changes.

Not sure what you're getting at.  Changing views on the relationships 
between taxa is not the fault of cladistics per se; it's a product of the 
research that goes on in trying to elucidate these relationships.  The 
inferred relationships between taxa may be presented as a cladogram; or as a 
Linnaean hierarchy; or as some hybrid system.  But don't shoot the 
messenger: changing cladograms are a function of ongoing research, not of 
some alleged instability of cladistic methodology.

(I would add that theropod cladograms have remained very stable over the 
past 10 years - at least for non-avian groups.  As for sauropods....)

BTW, don't be lulled into thinking there's something inherently stable about 
Linnaean taxonomy.  The almost militaristic rigidity of Linnaean ranks 
(Kingdom-Phylum-Class-Order, and the various derivative ranks in between) is 
a facade.  For example, I'd be astonished if you could find two 
ornithologists who agree absolutely on how many "orders" of birds should be 
recognized.  There is disagreement over whether certain time-honored bird 
orders are actually monophyletic (e.g., Coraciiformes, Pelecaniformes); and 
the exact position of certain modern birds (hoatzin, sandgrouse, flamingoes 
- to name a few) are still the subject of debate.




Tim

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