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Re: New ankylosaur from Liaoning

David Elliott (dalelemu@hotmail.com) wrote:

<Not quite a horny plate, but it has adaptations that imply it's a
bit more cursorial than the average ankylosaurian, so i don't know,
maybe its ancestors had something heavier like a plate there but lost
it for weight's sake? Im not sure how likely it is that a bony plate
would turn back into a set of scutes though... someone else here will
know better.>

  The structure in *Minmi* and *Liaoningosaurus* are both unique from
the ventral belly "armor" of other reptiles, such as aetosaurs (cf.
*Desmatosuchus*, *Aetosauroides*, etc., North American forms) in
being composed of hundreds of nodes and nodules, bound together in a
sheetlike matrix; that of aetosaurs consist of long transverse
"planks" of bone, or ossified dermal elements. Whether the sheet
whould have been impenetrable or hardened as a "shield" is not clear.
It does look as if the material comprises a sort of "chain-mail"
garb, as over the rest of the back in all ankylosaurs, thicker and
more tightly-bound over the pelvis and under the belly. The pelvic
shield is often preserved bound to the ilia in polacanthids like
*Mymoorapelta* and *Polacanthus*, but it is more likely to assume
that the belly shield was comprised of separate, mobile pieces.

  One thing the proportions of *Liaoningosaurus* and *Minmi* and
their belly armor do not show is cursorial or sub-cursorial
inclinations ... these animals are mediportal. Further comments will
wait as Mickey prepares his project on *Liaoningosaurus*, then I can
continue ;)

Jaime A. Headden

  Where the Wind Comes Sweeping Down the Pampas!!!!

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