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Re: Preview of new stegosaur plate paper

Don Ohmes (d_ohmes@yahoo.com) wrote:

<I said PASSIVE defense structures. Antlers are aggressive structures, not
defensive, and are ACTIVE, not passive. AND I DID NOT SAY "MUST'. And I will
"withdraw assertions" when someone makes a valid point.>

  Positively selected passive defense structures include the aforementioned
shells of tortoises and the similar but unique armor in glyptodont cingulatan
xenarthrans, wherein the largest vehicle-sized species have extremely developed
and fused "shells" fused to the pelvis and portions of the backbone, as well as
an elaborated head-shield fused to the calvarium with a tail "club" usually
involving a set of nodal spike (mace) or a set of spiked rings alternating with
unspiked rings. Other cingulatans have less ornamented armor, which is less
ossified and less fused to the skeleton as a whole. Nodosaur armor should also
show the same correlation if true (and if Ken's agonistic theory about
*Edmontonia* shoulder spikes proves incorrect, being agonistic), as in
*Sauropelta*'s elaborate cervical rings or the peripheral polacanthine body
"blades" that may not have all been used to engage a predator, but would have
functioned as deterrents nonetheless for being capable of doing so. Very small
ankylosaurs at adult size are rare, few, and far between, one being the
possible polacanthine (and dwarf) *Struthiosaurus* and it's apparent numerous
synonyms from the surrounding paleoisland regions. This taxon has small armor
compared to *Gastonia,* but then so it seems does *Polacanthus* which is larger
than the spikier *Hylaeosaurus*.


Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

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