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Re: TETRAPODS, PHYLOGENETIC TAXONOMY, AND CLEAR DEFINITIONS



In a message dated 98-07-27 03:05:00 EDT, 102354.2222@compuserve.com writes:

<< Along comes _Scutellosaurus_, or some similar organism, which has a
 plethora of armor scutes on the body and some other autapomorphies which
 allow us, several hundred million years later, to find it unique enough to
 found the clade Thyreophora.  >>

Has nobody ever wondered why stegosaurs and ankylosaurs look so different, if
they're supposed to be related to each other? I have, and I'm pretty sure that
stegosaurs are more closely related to the clade formed by marginocephalians
and ornithopods than they are to ankylosaurs. That is, the "clade" Thyreophora
is an illusion cast by the presence of dermal armor, together with a few other
minor characters, in both of its supposed subclades, and dermal armor occurs
in many other members of Ornithischia and Sauropoda. _Scutellosaurus_ and
_Scelidosaurus_ are basal ankylosaurians, not basal thyreophorans; they share
no stegosaur apomorphies that I can think of (can anyone?).