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Re: Therizanosaurs and Cladistics
>In any case, I am still a little reserved at calling these beasts
>theropods (that tetradactyl pes still has a _lot_ of explaining), but the
>idea isn't quite as absurd as I otiginally thought it to be when Thom Holtz
>started his whole _Alxasaurus_ kick a few months ago.
Actually, the tetradactyl foot isn't incompatible with the theropod
clade. All theropods have 4 toes. Most birds (flying theropods) have four
functional toes. Some (such as the ostrich) have two functional toes.
Most non-avian theropods (such as T. rex) have 4 toes, with three of which
contact the ground. The other toe is situated high on the foot,
behind the 3 other toes. It seems a little counter-intuitive to call a
dinosaur with four toes contacting the ground a theropod, but there is
nothing wrong in the cladistic sense by doing so.
From a "Linnaean point of view", on the other hand, having four toes in
contact with the ground MAY be reason-enough to put it in another group....
... but of course, since Linnaean systematics is EXTREMELY opinion-based,
it will depend on which Linnaean systematicist you ask.
> My vote for diet is herbivore. This is because of the teeth, and it's
>not especially preditory demeaner (not especcially fast, small head, giant
You might be right. But that doesn't preclude the possibility that it is
still a theropod.
> In any case I will be (in the days to follow, maybe today) sending y'all
> my family tree of dinosaurs as I see it. I will attempt to send you two
>trees, one linnean, the other cladistic.
Actually, you'll be sending us *one* tree. The other is a hierarchial grouping.
Cladistics is a "family tree" of sorts. But Linnaean systematics
is nothing more than putting name-labels on organisms. No
family-tree is implied in Linnaean systematics.