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Re: Diplodocus: Return to the Swamps????



Fowler/Williams/Chure -- 'vertical limb elements'.

Basic assumption -- the "vertical limb elements" found at various locations do 
indeed represent sauropods that died with their legs embedded in soft 
sediments. 

Conclusion -- most concisely, this in fact proves that sauropods definitely at 
least on occasion ventured into areas of soft footing. At least occasionally 
they died in that position.

Further -- There are various scenarios that can be logically associated with 
limb elements found in "mired position". 

The primary case is, "Death occurred as a direct result of being immobilized by 
soft sediments." This case, even if proven in a particular instance, does not 
serve to reject speculation that sauropods utilized areas of soft sediments and 
overlying water as areas of refuge from predation by theropods, and/or sources 
of elevated browse inaccessible to other herbivores. In other words, the 
proposition: "This sauropod mired and died with it's limbs embedded in soft 
sediments, therefore all sauropods that had their limbs embedded in soft 
sediments must have mired and died."  is fallacious on it's face. Or re-stated 
yet again, 'utilization of "swamp" by sauropods' as a viable concept does not 
hinge on proving they were 'impossible to mire', or even 'impossible to eat'.

Given that: a) over time, many sauropods must have been forced by circumstance 
into soft sediments, whatever their actual physical 
capabilities/vulnerabilities or behavioral characteristics were, and b) there 
is a relatively high probability of preservation of a mired carcass, it would 
be expected that a significant percentage of sauropod fossils would be in the 
'mired position', were they highly vulnerable to death by miring, or even the 
occurrence of death while in 'mired postion'.*  

I had hoped to get to the library and do some reading, but weather, other 
activities and "Christmas library hours" intervened. I mention this because I 
wished to confirm my deduction that Janensch used the 'mired sauropod' to 
support his contention that sauropo
I was unable to do so, yet. Also, trackways apparently support the idea that 
sauropods traveled in groups, in ground soft enough to preserve tracks. Were 
they highly vulnerable to miring, one might expect to find evidence of miring 
episodes that involved multiple individuals. I think there is at least one 
candidate locality, but am not sure. Another path left untraveled, but the 
library will re-open sometime, and I might make it there when it does, so maybe 
later for that.

*I assume that such 'vertical' finds are _relatively_ rare, but that is only an 
assumption on my part. Perhaps someone already knowledgeable could comment on 
that assumption? Even a rough estimate of 'mired' vs 'unmired' specimens is 
likely more than I can take on.

--- On Mon, 12/14/09, Denver Fowler <df9465@yahoo.co.uk> wrote:

> From: Denver Fowler <df9465@yahoo.co.uk>
> Subject: Re: Diplodocus: Return to the Swamps????
> To: dinosaur@usc.edu
> Date: Monday, December 14, 2009, 1:02 AM
> Sauropod remains consistent with
> miring events are known from a number of localities
> including:
> 
> the mother's day site (Morrison Fm, Montana), although
> newer interpretations disagree (e.g. Myers & Storrs,
> 2007)
> 
> 1992 'Brachiosaur', Wessex Fm, UK
> unpublished 'diplodocoid' Wessex Fm, UK
> I recall that at least one limb was found upright at the
> Howe quarry.
> Fiorillo's abstracts at SVP & GSA 2001: Alamosaurus
> material from Big Bend, TX
> 
>  ----------------------------------
> Denver Fowler
> df9465@yahoo.co..uk
> http://www.denverfowler.com
> -----------------------------------
> 
> 
> 
> ----- Original Message ----
> From: Tim Williams <tijawi@yahoo.com>
> To: dinosaur@usc.edu
> Cc: tijawi@yahoo.com
> Sent: Sun, 13 December, 2009 21:52:19
> Subject: Re: Diplodocus: Return to the Swamps????
> 
> 
> Although I don't have a dog in this race, this thread
> reminds me of the taphonomy one of the larger specimens of
> the sauropod _Giraffatitan brancai_.  The humerus and a
> tibia of this specimen (SII) were preserved in an upright
> positi
914) to adduce that the
> individual had been mired in soft mud before burial.
> 
> 
> This was at "Tendaguru Site S", as discussed by Heinrich
> (1999) in his summary of the taphonomy of the Tendaguru
> dinosaur locality.
> 
> 
> Cheers
> 
> Tim
> 
> 
> --- On Sun, 12/13/09, don ohmes <d_ohmes@yahoo.com>
> wrote:
> 
> > From: don ohmes <d_ohmes@yahoo.com>
> > Subject: Re: Diplodocus: Return to the Swamps????
> > To: dinosaur@usc.edu
> > Date: Sunday, December 13, 2009, 10:35 PM
> > --- On Mon, 12/14/09, Jonas
> > Weselake-George <Paleo@ncf.ca>
> > wrote:
> > 
> > > From: Jonas Weselake-George <Paleo@ncf.ca>
> > > Subject: Re: Diplodocus: Return to the
> Swamps????
> > > To: dannj@alphalink.com.au,
> > dinosaur@usc.edu
> > > Date: Monday, December 14, 2009, 1:13 AM
> > > 
> > > Dann Pigdon <dannj@alphalink.com.au>
> > > wrote:
> > > "It goes in splayed with plenty of resistance
> > (limiting the
> > > depth of penetration), but is drawn out with
> converged
> > toes
> > > that offer far less resistance. Sauropods, on
> the
> > other
> > > hand, would have had to fight each step to extra
> 
> > foot
> > > from deep mud. That's bound to tire a large
> animal out
> > after
> > > a while."
> > > 
> > > What about taking into account mass (and muscle
> mass)
> > vs.
> > > limb surface area? It would seem to me that a
> fifteen
> > ton
> > > sauropod would experience less relative suction
> than a
> > one
> > > ton theropod. What do you think? 
> > 
> > Exactly. Re is critical (or perhaps some related but
> more
> > situation-appropriate and specialized metric). Mud is
> > essentially less dense/viscous for larger animals...
> >  
> > > Additionally, the sauropod would tend to punch
> through
> > to
> > > the substrate more easily and would also have
> four
> > limbs for
> > > balance. I'm not arguing that it'd be easy, but
> a
> > large
> > > sauropod might have an advantage in moving
> through a
> > swamp
> > > (not that it is very likely a theropod one
> fifteenth
> > its
> > > weight would have a motivation to foll
at repeatedly sheared mud tends to
> liquify.
> > In other words, if you have the power to shear it in
> the
> > first place, it becomes easier w/ each shearing. And
> less
> > supportive to any splay-footed interloper. 
> >  
> > > A more likely situation would be sauropods
> taking
> > advantage
> > > of the mud to mate (after all I saw a paper
> suggesting
> > that
> > > an early cretaceous ornithopod population was
> using
> > swamps
> > > for shelter during the breeding season).
> > 
> > What is unlikely about a theropod-free zone?
> > 
> > Anyhow, to bed for me...
> > 
> 
> 
>       
> 
>