Re: re:dino mimicry

[Tom Holtz <tholtz@geochange.er.usgs.gov>]

>The anatomy of the Anky's tail would seem to prevent it from raising it to a
>significant angle above the horizontal as there are interlocking dorsal
>processes
>connecting the individual caudal vertebrae in a very rigid looking manner
>and there are no
>attachment sites for the muscles that would be needed to hold the tail
>semi-erect.
>I agree that it would be a very ineffectual weapon against any significant
>predator.

Actually, it wouldn't have to strike to high.  The metatarsus (the long
bones of the foot) are probably the weakest point of the theropod anatomy
(it is certainly as thin or thinner than the shin or thigh), and is right
in target.

One problem I have with this mimicry idea is the biogeography of it -
ankylosaurIDs with good tail-clubs are not common where "iguanodontids" are
found.  Instead, ankylosaurids are found with ceratopsians, hadrosaurids,
hypsilophodontids, pachycephalosaurs, a butt-load (standard paleoecological
term... ;-)) of small theropods, and the occasional sauropod.  The
ankylosaurIANs that are found with iguanodontids are, for the most part,
nodosaurids and "polacanthids" (and whatever the hell Minmi is!?!), none of
which have the elaborate tail-clubs of the Ankylosauridae.

So, if the ankylosaurids were mimicing anything, it probably wasn't Iguanodon.

I still haven't seen the Thulborn paper, so maybe there are arguments that
haven't been posted favoing this idea.  However, I have no problem with
anklyosaurid tail-clubs as defensive weapons, protecting the back the way
stegosaurian "thagomizers" were probably used.

                                
Thomas R. Holtz, Jr.                                   
tholtz@geochange.er.usgs.gov
Vertebrate Paleontologist in Exile                  Phone:      703-648-5280
U.S. Geological Survey                                FAX:      703-648-5420
Branch of Paleontology & Stratigraphy
MS 970 National Center
Reston, VA  22092
U.S.A.