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RE: Diplodocus: Return to the Swamps????



But... Why mud at all? Couldn't sauropods have favored bodies of water with 
sand and/or gravel, rather than mud? You know, big sandy- or gravelly-shored 
lakes rather than mucky bayous.

But anyway... This video 
(http://www.youtube.com/watch?v=Gp-0BtK1zIk&feature=player_embedded#) has good 
footage of a walking hippopotamus, with some close-ups of the feet. From 0:13 
to 0:23 in the vid you really see how tiny (relative to the animal's body size) 
and compact they are. So, we have at least one case of a swamp-lover with 
smallish, compact feet. The Sauropoda *may* have been a second case.

Just some random thoughts.

~ Michael

----------------------------------------
> Date: Sun, 13 Dec 2009 20:22:03 -0800
> From: d_ohmes@yahoo.com
> To: dinosaur@usc.edu
> Subject: Re: Diplodocus: Return to the Swamps????
>
> --- On Sun, 12/13/09, Dann Pigdon wrote:
>
>> From: Dann Pigdon
>> Subject: Re: Diplodocus: Return to the Swamps????
>> To: dinosaur@usc.edu
>> Date: Sunday, December 13, 2009, 10:39 PM
>> Here's a good reconstruction of what
>> a theropod foot looks like going into and coming out of mud,
>>
>> courtesy of Stephen Gatesy:
>>
>> http://www.brown.edu/Administration/News_Bureau/1998-99/98-123g.html
>>
>> 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.
>
> All true. But again you miss the reality of a swamp. There is a depth at 
> which the theropod is helpless and can be simply run over.
>
>> Sauropods,
>> on the other hand, would have had to
>> fight each step to extract a foot from deep mud. That's
>> bound to tire a large animal out after a
>> while.
>
> In deep mud, there isn't real extraction in the sense that the foot clears 
> the surface. The foot is lifted, and moved forward _through_ the mud. Only 
> large animals can do it at all, and the larger you are, the easier it is to 
> do in a given mud. Longer legs (absolute, not relative length) have more 
> leverage, and can reach deeper bottoms. Toes are not helpful. Again, you can 
> experiment w/ this yourself.
>
>> Bipeds also had the option of walking plantigrade with
>> their ankles flat to the mud, for which there
>> is trackway evidence:
>>
>> http://paleo.cc/paluxy/elong.htm
>>
>> It would have been awkward, but would have provided even
>> more surface area to prevent sinking
>> in the first place.
>
> Again, we are taking the sinking case. Going _over_ a deep swamp* (the 
> non-sinking case) isn't an option for multi-ton cursorial bipeds, especially 
> after thorough turbation and mixing by much larger and longer-legged quads. 
> Going through one (the sinking case) is where large quads excel. After a 
> period of time, a swamp would become thoroughly sauropod-ized, and certain 
> failure for any large theropod.
>
> Now I am out of time. Being a longtime Swamp Thing fan (I lost #1 in a house 
> fire), I have no answer to the elegant arguments of Lee Hall, but will answer 
> any comments that show a modicum of thought when time permits... which will 
> be later in the week, or next weekend.
>
> *chest-deep on a man or deeper...
>
>                                         
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