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Re: Pachys



Whooooaaaaahhh there Ralph!

Firstly, thanks for posting the reference on pachy sexual dimorphism and I
hope to look up a copy soon. No, I am not accusing you or anyone of SOP (is
that an acronym?) it is just that the popular accounts I have read on the
issue do smack of ad-hoc arguements. Now I have the references you provide,
I look forward to reading something a little more meaty! I also look
forward to seeing the description of the new pachy you mention.

OK, so if I take your arguemnt of sexual dimorphism as read, how does this
reflect on the functional anatomy of pachys? What is it about their anatomy
that is different? That seems to me to be at the bottom of an
interpretation of their functional morphology.

And I am not debating that the domes were most probably used for impacting,
I am questioning what they were impacting and how they were doing it. In
this sense, we are both in agreement that;

> Running a 1/4 mile before bashing would be another story and
> I agree that seems out of the reasonable area.

I also agree that:

> We just need to develop
> strong functional and phylogenetic models to determine, if we can, whether
> either or both are favored among the flank/head-on models. I agree with
> Kevin in that I think we can get there.
>

Are you familiar with the game of conkers or knuckles? This would seem a
more reasonable analogy for the function of the pachy head, inter- or
intra- specifically. But, unless a stable platform can be demonstrated to
exist on a pachy skull, I can't accept that mutual shoving or, heavens
forbid, head-to-head ramming is a reasonable intepretation.

As for the postcranial arguement, I am still yet to determine exactly what
it is about the postcrania this indicates a high impact beast or that any
bracing that does exist is in responce to high speed collisions. Can you
point me in the right direction for more literature on this matter?

I am not attacking others work, just asking how well supported it is and
exactly what they actually mean.

If I do have a genuine beef it must be that, while we agree that;

> Running a 1/4 mile before bashing would be another story and
> I agree that seems out of the reasonable area.

this is _precicely_ how such conflicts are depicted in popular literature
and culture. While it is easy to dismiss responsibility for the
perpetuation of such conceptions, ultimately they do originate from
professional palaeontologists. Some over enthusiastic authority explains to
a scientifically illerate journalist that pachys has sexual combats "in the
same way that mountain goats do today" and, hey presto, all pachys are;

> Running a 1/4 mile before bashing ...

There is then a lot of work for everybody to clarify exactly what the
original authors really said and then put the record straight.

To conclude an already overlong post, I am not trying to rewrite the
functional biology of pachys. I am simply asking how firmly grounded the
currently accepted interpretations are and pointing out a few features that
seem to me to be inconsistent. I don't mean to butt heads with anyone along
the way!

Cheers, Paul

pwillis@ozemail.com.au

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