[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Sue's head, cartilage, and whatnot...(kinda long)



Just a small observation from one who once taught anatomy and physiology for
a living; be aware in your discussions that cartilage dries out to a very
dramatic degree post-mortem. Thus, any cartilaginous "tissue" which
fossilises is going to appear much thinner than it would in life - (ie the
so-called "mummified" fossil material) or, more likely that once the
cartilage dehydrates post-mortem, the intervertebral gaps will 'shrink' - it
is this shrinking (or stenotic response) between vertebra and at articular
interfaces along with the post-mortem tightening through rigormortis and
dehydration of tendonal tissue which causes the arched neck position of many
finds which once led to the theory that the dinosaurs died from toxic
influence and died in convulsive agony.

I think the 10% figure is getting closer to the true figure and will
ultimately rnder a more complete and 'truer' rendition of a diagrammatic
reconstruction.

Muttley


----- Original Message -----
From: <DinoBoyGraphics@aol.com>
To: <dinosaur@usc.edu>
Sent: Monday, November 03, 2003 9:24 AM
Subject: Sue's head, cartilage, and whatnot...(kinda long)


> Just to respond to a few good points brought up:
>
> Jon, aka Trouble Stirrer:  You maybe right about the room for the
cartilage between the vertebrae:  10% is a value commonly given, but the
amount is variable.  I got to play witha  cast of "Stan" this summer, and I
suspect something closer to 5% is accurate, which may be consistent with the
stiff-ish backs fo coleurosaurs (or at least tyrannosaurs).  As for the
limbs, I don't believe in the dogmatic "dinosaurs had thick cartilageouness
joints" bit.  I don't think they would have had substantially thicker joint
cartilage than mammals (e.g. a thin veneer of hyline cartilage).  On the
other hand, if "Sue" really is a subadult (what would be up with that?!),
then I am wrong and there probably should be more limb-joiint cartilage.
Pick your favorite excuse ;)
>
> David brought up the cartilaginous episternum which is drawn but may not
have been present.  Although I think there are good phylogenetic reasons to
infer such a structure, you will kindly notice that I did not draw it on the
rigerous detail of Sue and what is known of "her."  So the viewer is left to
decide whether to believe me or not in my assumption.
>
> And finally, Mr. Varner (thanks for the frequent art-related notices, by
the way Dan!) asked about restoring squashed skulls.  Actually, I think he
was asking Jon, but since I'm the culprite in this case, I thought I'd chime
in anyhow.  In the case of FMNH PR2081 the situation isn't quite as bad as
it appears.  The jugal, squamosal, quadratojugal, and postorbital are more
disarticulated than deformed, so it isn't too difficult.  The nasals are
squashed all to heck, but the premax isnt, so with a little tlc inr estoring
he lacrimal (which isn't too squished, anyhow), ant the premax/lacrimal
positions nicely constrain the nasals and the dosral extent of the maxilla.
>
> I'm not sure that the "differences" warant generic seperation yet, because
I'm not convinced that the AMNH skull isn't different in large part due to
it's own distortion.  But then again, maybe there are two species of
tyrannosaur running around the maastrichtian of N.A.
>
> All the best,
>
> Scott
>
>
> Scott Hartman
> Zoology & Physiology
> University of Wyoming
> Laramie, WY 82070
>
> (307) 742-3799
>