Re: Sauropod necks????

[dinoboygraphics@aol.com]

> > Long necks in large sauropods probably served to
> > enhance the _kilos of forage per step_ ratio.
>
> Is holding a neck horizontally and swinging it around really cheaper 
than
> taking a few steps? GSP says no...

> Perhaps not cheaper, but certainly safer. It would seem to me that the
> fewer steps an adult sauropod had to take the better. A single stumble
> would probably have crippled the largest animals.

I'm sorry, this is positively wrong.  I've crunched the numbers without 
ever seeing GSPs numbers, and there is no way to make long necks 
economical for low browsing.  The cost of supporting all that extra 
tissue (in calories/hour) 24/7, plus the extra work to overcome all 
that tracheal deadspace (or, alternatively, to overcome all the laminar 
flow friction from a hyper-narrow trachea) is FAR, FAR more 
energetically expensive than simply walking a few steps forward to 
continue browsing.  There is no energetic benefit what so ever when an 
animal "enhance(s) the _kilos of forage per step_ ratio" in this way.  
That's presumably why all extant grazers and low browsers have necks 
that are just long enough to get the mouth down to the ground.  Worse, 
locomotion actually gets cheaper (relative to daily energy budget) as 
you get larger, so sauropods would have less incentive to lengthen 
their necks for low browsing than horses or rabbits would.

As for it being "safer", why on earth would that be?  Quadrupedal 
animls almost never fall when they are moving slowly; They are 
inherently stable, unlike bipeds at all speeds.  In addition, the 
increased danger of starvation (since you are dramatically increasing 
your daily energy budget by growing those long necks) plus the 
increased chance of injury to those long necks (from predation or just 
accidently whacking it against something) would seem to be at least as 
great as the almost non-existent problem of a quadruped tripping while 
it's ambling along.

I know that cows occasionally fall down ravines, but we seem to have 
bred good judgement out of them.  I challenge anyone to find a 
reference to a large herbivore.


Scott Hartman
Science Director
Wyoming Dinosaur Center

110 Carter Ranch Rd.
Thermopolis, WY 82443

(408) 483-9284
www.skeletaldrawing.com

-----Original Message-----
From: Dann Pigdon <dannj@alphalink.com.au>
To: DML <dinosaur@usc.edu>
Sent: Mon, 30 May 2005 07:47:34 +1000
Subject: Re: Sauropod necks????


David Marjanovic wrote:

> ----- Original Message -----
> From: "don ohmes" <d_ohmes@yahoo.com>
> Sent: Wednesday, May 18, 2005 5:52 PM
>
> > Long necks in large sauropods probably served to
> > enhance the _kilos of forage per step_ ratio.
>
> Is holding a neck horizontally and swinging it around really cheaper 
than
> taking a few steps? GSP says no...

Perhaps not cheaper, but certainly safer. It would seem to me that the
fewer steps an adult sauropod had to take the better. A single stumble
would probably have crippled the largest animals.

--
___________________________________________________________________

Dann Pigdon
GIS / Archaeologist         http://www.geocities.com/dannsdinosaurs
Melbourne, Australia        http://heretichides.soffiles.com
___________________________________________________________________