Re: Lack of Running Giant Theropod Tracks

["Habib, Michael" <MHabib@Chatham.edu>]

On Nov 29, 2010, at 10:44 AM, Don Ohmes wrote:

> On 11/28/2010 10:46 PM, Sim Koning wrote:
>> As Habib has pointed out, most predators do not make a habit of attacking 
>> animals that are several times larger than themselves...unless they are in 
>> packs.
> 
> Nearest living relatives of the giant bipeds -- golden eagle, harpy, ... 
> do I need go on? There are more...

They fly.  You'll note that in my original post the noted exceptions were packs 
and flying predators.  Flight is a huge advantage.  
[Even then, eagles do not regularly hunt animals 10-20x their mass.  Some 
species will very occasionally kill prey up to 3x their total mass].

> The idea that we can divine the behavior of theropods by averaging the 
> behavior of living predators, none of which are morphologically 
> analogous beyond the fact they have teeth, is weak.

The idea that we can divine the behavior of theropods by using a thought 
experiment or speculating on tactical blow-by-blow scenarios is far weaker, 
still.  Furthermore, the trend in living predators cuts across a wide range of 
morphologies, so the importance of prey mass is apparently not that sensitive 
to morphology.  We can make suppositions all day about how a predator should be 
able to kill one thing or the other, but in reality, most of the encounters 
don't happen.  

> The argument boils down to "But, gosh, they were so big..."

Darn straight - and being big matters A LOT.  

> I am making a case based on the respective morphologies that outlines 
> the tactical situation in play when giant sauropod met giant theropod. 
> To do this in logical fashion, you have to start w/ a one on one scenario.

And given the difficulties in scenario building, this already places one in a 
weak position from which to argue a case.  Trying to reconstruct a "tactical 
situation" using a thought experiment is just not very robust.  

I will say, however, that you have raised an interesting morphological 
question: just how well protected were the deeper arteries of a sauropod?  I 
think the vital structures would actually be a lot harder to hit than you give 
credit for; I presume you'd disagree, but regardless, that is something we can 
actually analyze.  Sauropod workers: any information on the estimated amount of 
muscular tissue and other connective elements protecting the vital deep 
structures of a sauropod neck?

> Those who can clear their minds, however briefly, of the Freudian 
> implications will realize -- on good footing, the theropods had an 
> overwhelming tactical advantage. Perhaps they were not smart enough or 
> bold enough to exploit it effectively, but it was there. On bad footing, 
> the situation was reversed.

Maybe or maybe not, but apparently sauropods didn't get slaughtered on solid 
ground regularly, because all evidence we have from morphology, taphonomy, 
ichnology, and biogeography indicates that sauropods were primarily inhabiting 
dry, open environments.  This does not mean they never went through a forest or 
swamp, but concocting scenarios in which they were reliant on such habitats is 
inconsistent with the evidence at hand.  

Cheers,

--Mike


Michael Habib
Assistant Professor of Biology
Chatham University
Woodland Road, Pittsburgh PA  15232
Buhl Hall, Room 226A
mhabib@chatham.edu
(443) 280-0181