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Re: Mesozoic terrain (long)




On Thu, 16 Jul 1998, Jeffrey Willson wrote:

>> I believe it was L. Sprague de Camp in _Day of the Dinosaur_ who opined
>> that, since grass had not evolved during the Mesozoic, ipso facto the
>> terrain must have been cut up by erosion into innumerable gullies and
>> ravines of small, medium, and large size. If true, this would certainly have
>> had repercussions on dino locomotion and behavior.

>> Now it "seems" to me that the multi-tonners, pretty much across the board,
>> are not particularly well designed to negotiate this sort of rough terrain.

>> Comments?

William Gibson Parker <wgp@dana.ucc.nau.edu> replied:

>Here we go again with what these animals could not do.  Again, they were
>extremely successful creatures which evolved over long periods of time.
>If they could not deal with the environment they either a)would not have
>survived, which of course they did, b) developed features which let them
>deal with this environment, or c)migrated to an area where they could
>survive.  I could not imagine Sauropods living in an environment they
>were not capable of survival in , therefore the terrain in these areas
>could not have posed that much of a threat.
>-Bill Parker
>Northern Arizona University

>  How did my previous post turn into this turkey thread?!  Between that
>and the cows we have the barnyard list.  Dinotipping!:-) I do like that.


  Sir. 

I did not say what dinos "could not do". 

I believe I was careful to say de Camp "opined" a hypothesis, about which
ramifications "seemed" to me to follow.

It seems to me that two possibilities which follow from the info I posted are

A) de Camp doesn't know beans. 

B) large dinos *are* well adapted to rough terrain, and here's why...

I couldn't possibly agree with you more that sauropods & other dinos were
well adapted!!!

My post was a question about a specific "how were they adapted?" and "to what?".


"James R. Cunningham" <jrccea@bellsouth.net>
posted a helpful, informative, and friendly reply:

>This creates a lot of rilling, but also a lot of deposition in local flood
plains.  The
>erosion process creates about as much 'geometrically suitible' sauropod
habitat as it >destroys.  This is even more true of my original home in the
Mississippi delta of >eastern Arkansas where I've run level lines for
several miles without ever having to go >to high rod.

>So yes, there would have been repercussions on habitat, but they wouldn't
have been >catastrophic.  They'd just have moved the animals' preferred
range about a bit.

So we're talking about long and wide branching flood plains with rougher
slopes at the borders. The big dinos have no problems negotiating the
bottomlands or the "tops", but moving from one to the other *may* be
problematical. I've seen various films of bison and African ungulate herds
negotiating similar slopes by treading down long and narrow "ramps" and it's
tough for them, especially in herds. When one takes a tumble - "domino
effect". I'd guess bad for sauropods. 

If we mean that the "preferred ranges" were actually "moving" from year to
year due to erosion, I'd call this "serious" if not catastrophic. We can
assume (or can we?) that big sauropod herds & maybe others had huge impacts
on local plant biomass, so they must have had to keep moving to find food
(??). The difficulty (again, if there was one) of negotiating slopes must
have been a factor in their behavior and that of their predators. 

(As the Pack chases the Herd into a box canyon, the lead sauropods begin
pawing at the slopes, trying to start a ramp. At the rear of the herd, 400
tonnes of panicked herbivore collide. A big cow slips and falls, and the
theropods are on her, trying to dodge the lashing tails of the others.)

or:

(As the Pack breaks cover from a grove of trees half a klick down the
floodplain, the sauropods quickly but calmly amble toward the nearest
side-gully in the bank. They crowd in, the calves trotting forward between
the great swaying legs of the adults. As the theropods approach, they are
presented with a solid wall of sauropod posteriors, deadly tails lashing.
The theropods wait hopefully for a quarter-hour, but unable to grab a calf
or approach an adult from the vulnerable fore-quarters, they eventually
retreat, hoping to find another Herd they can catch further away from the
protecting walls.)

(I am new to this list. After re-reading the List's "Administrative Message"
and especially Section 8 of "Things Not To Do" I decided to include the
fictive bits. If I am informed that this is bad list ettiquette I won't do
it again. Thanks.)


(Whats the back-of-the-envelope math on the energy needed to raise a 20,000
kilo dinosaur 10 meters?).

Jeffrey Willson <jwillson@harper.cc.il.us>