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Re: TETRAPODS, PHYLOGENETIC TAXONOMY, AND CLEAR DEFINITIONS
>Thomas R. Holtz, Jr. wrote:
>> I'll try and keep this one brief.
>So will I. Why does it seem that certain people on this list are incapable of
>comprehending simple English?
>> >Would it? If the diagnosis of Dinosauria is as you state, then an animal
>> must have
>> >both those features to be a dinosaur.
>> Ankylosaurs don't have a perforate acetabulum: they must not be dinosaurs
>> under your rules.
>I said **IF**, didn't I? See, right there: "If the diagnosis of
>Dinosauria is as
>you state, then . . ." The presence of the word "if" makes the statement a
>conditional one: _if_ X is true, _then_ Y follows.
But the IF is irrelevant, because perforate acetabula DO diagnose
Dinosauria, and ankylosaurs ARE dinosaurs. This is why character states
are useful for diagnoses, but lousy for definitions.
Postdoctoral Research Scientist
Department of Geology
Field Museum of Natural History
Lake Shore Drive at Roosevelt Road
Chicago, IL 60605 USA
phone: 312-922-9410, ext. 469