Re: Sauropod Neck

["Matthew Bonnan" <mbonnan@hotmail.com>]

John Schneiderman said:

> I see only about 45 degrees of arc (side to side or and up and down) if
> the mounts of (non-brachiosaur) sauropods are correct.  I see sauropods as
> constantly moving foragers (browsing on whatever plants they approach).

I'll have to post the Parrish and Stevens ref tomorrow.  Diplodocus does 
have a more restricted side to side motion, but Apatosaurus has a large arc 
of motion.  The motion of ventriflexion (bending the neck down) is very 
great in both Diplodocus and Apatosaurus, so they're necks are very flexible 
in that plane.  Again, I will post the ref tomorrow.

> Trackways attributed to sauropods suggest herding behavior, so masses of
> animals on the move (in about the same direction) have little opportunity
> for or need of a wider degree of arc for browsing.  And there is the
> "knock-down" the tree method of getting to the canopy of leaves.  Just
> strip, swallow and move on.

Sure, but this assumes a number of things.  Sauropods may not have been all 
that fast.  So, they were probably on the move, but how fast they were 
moving would make a huge difference in how they would feed.  If you can 
stand still and just use your neck to forage, you would save a lot more 
energy than if you quickly walked by getting what you could.  You could, of 
course, knock down trees, but this is assuming there would be enough of a 
meal there to do it.  Imagine a group of large sauropods following a 
riverbank, some in the river, others on its banks, slowly putting one foot 
foward and swinging their necks up, down, and side to side eating ferns, 
cycads, and horsetails.  This is at least what I imagine was going on with 
some sauropods.  They were not fast creatures by any stretch of the 
imagination.

As far as animals on the move, the temptation with sauropods is to want to 
compare them with large mammalian herbivores like elephants and giraffes, 
neither of which is a good model for sauropods.  We must be careful not to 
take behavioral cues from extant large mammals as a way of interpreting 
dinosaur behavior, lifestyle, etc.  We don't know a sauropod's physiology, 
we have no way to gauge metabolism, etc., so it's difficult to say how much 
food they would need and how fast they'd need to get it.

Plus, the trackways do show a bunch of sauropods moving together, but it 
tells us nothing about herding behavior necessarily.  A geographic feature, 
like a lakeshore, may have made it necessary for a bunch of sauropods to 
walk through the same area without necessarily being in a herd.  They may 
very well have herded, but we are still unclear on this.  We do know many 
different kinds of sauropods lived together in the same areas, and how they 
competed with each other is still a bit of a mystery (one I am trying to 
unravel from one particular outlook).

In any case, sauropods are so alien that we must be careful when we 
interpret any aspect of their paleobiology.  I'll post the neck ref, and I 
encourage anyone who hasn't read it to read it and see what you think from 
there.

Matt Bonnan

> -----------------
> John Schneiderman
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