RE: Bipedal apatosaurs and stegosaurs?

["Cunningham, Betty" <Cunningham@sega.com>]

Rob Meyerson wrote:

>>I still believe that the sauropods most effective feeding method
>>would be for the larger animals to 'walk' up a tree trunk

> I hate to be a wet-blanket, but I am unconvinced of the "tripod"
> feeding model for sauropods.

I'm not saying they fed REGULARILY like this, but could feed like this as   
an advantage over NON-rearing sauropods.

>When one considers the high browsers of today (i.e. elephants and
> giraffes) one occasionally sees them rearing to reach high branches.
> However, this is not their primary mode of feeding.  When food is
> scarce, and they need to eat more of the tree, *then* they will rear
> up to reach higher foliage.  Elephants will go one step further by
> bringing down the whole tree for easier consumption (Note that the
> elephant *prefers* to feed on the tree when it has been felled).
> When it comes down to it, rearing up to feed requires a lot more
> energy (and is therefore less efficient) than simply standing and
> munching on what is readily available.

   As I said in my post, the modern (African) elephant which will strip a   
tree to the ground if hungry.   They won't just push the tree over with   
their trunk, but will rub on the tree, push the tree over with it's   
forehead, push with one foot, walk up the tree's side, push the tree over   
with it's butt, and twist smaller trees between their tusks.  (I've seen   
National Geographic specials)  Does that mean they don't PRIMARILY feed   
out of downed trees?  Maybe, sure.  But it does show they are awfully   
good at it.  (Giraffes don't feed well off the ground, so do elephants   
have advantages over giraffes in areas where the browsing is bad?)

Think of a sauropod herd wondering around browsing at what ever level the   
paleontologists agree that they feed at, with juveniles either trailing   
along eating whatever the bigger ones dropped, or browsing on their own   
at their own level (AND somehow not competing with the bigger ones of   
their own species that could, assumedly, reach the same browse as shorter   
juveniles). These guys may not be pulling down every tree within reach,   
but if hungry, a sauropod species that can rear up to knock over a tree   
(and coincidentally put more browse into the reach of the juveniles) will   
survive better than one that found it difficult to do so.  ESPECIALLY in   
situations where browse material becomes scarce for whatever reason.

And as to another post that suggested that sauropods might be able to   
knock over a tree with their neck in preference to walking up a tree,   
well, yeah, sure.  The modern elephant proves there's more than one way   
to knock over a tree.  However, IMHO, a 10+ ton animal pushing a tree   
over by walking itself up the side seems more energy efficient and likely   
than swinging a 20+ foot long neck in a forest.  Again, how could it see   
to aim?  How much room would it need to swing?  Would it hit the tree   
with repeated whacks (like swinging a blunt axe) till the tree fell over   
or would it just push in from the side?  The leverage seems a little   
unwieldy to me.  Possible, of course, just unwieldy.

And I don't know how flexible these necks were, but if the head can be   
placed within reach of branches to feed at 30+ feet of the ground, surely   
it can't be that much difficult to look up (or down to check where it's   
feet were going) at the same time, if it wanted to rear, right?

 -Betty Cunningham