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Re: TETRAPODS, PHYLOGENETIC TAXONOMY, AND CLEAR DEFINITIONS
I'll try and keep this one brief.
At 10:30 PM 7/23/98 -0400, Jonathon Woolf wrote:
>> This really was no different in the Linnean system. We can consider a
>> taxon to have several properties: name definition, diagnosis, group
>> membership, timing of origin. The Linnean system effectively tried to
>> maximize the stability of the diagnosis, but diagnoses were still labile:
>> were we to diagnose Dinosauria on the basis of a perforate acetabulum and
>> inturned femoral head, and then discover some new fossil with one but not
>> the other, the diagnosis would still require modification.
>Would it? If the diagnosis of Dinosauria is as you state, then an animal
>both those features to be a dinosaur.
Ankylosaurs don't have a perforate acetabulum: they must not be dinosaurs
under your rules.
>Remember, I'm a programmer. Boolean logic:
>(A AND B) is true if and only if A is true and B is also true. (I'm sure you
>already know that, but an awful lot of stuff I've said lately has been badly
>misconstrued, and I want to avoid any more of that.) If taxon M is
diagnosed by 22
>characteristics, and organism X has 21 of those characteristics, then X isn't a
>member of M.
Ankylosaurs aren't dinosaurs, whales aren't tetrapods, kiwis aren't birds.
You're a programmer: great. However, we are talking about organisms which
have a history of descent with modification, not software written from scratch.
Thomas R. Holtz, Jr.
Vertebrate Paleontologist Webpage: http://www.geol.umd.edu
Dept. of Geology Email:email@example.com
University of Maryland Phone:301-405-4084
College Park, MD 20742 Fax: 301-314-9661