Re: read and learn

[Chris Campbell <sankarah@ou.edu>]

Colette H. Adams wrote:
> 
> Greg, you're priceless.  The man knows his shit, boys and girls.  Read and
> learn.  Incidentally, I'm ordering another copy of Predatory Dinosaurs of
> the World to replace one I gave to a young friend of mine.  It is only the
> second book I've bought this year.  On $5.45/hr I am very choosy.
> 
> Other than that I will continue to remain silent on the bioenergetics issue
> for now.
> 
> Here's a can of worms I actually would like to open.  On many occasions I
> have heard it suggested that ceratopsians would have turned on their
> attackers and used their horns for defense rather than flee.  Forgive me,
> both those who suggest such a thing do not understand natural selection.
> Let's imagine we have a herd of ceratopsians.  A tyrannosaur shows up.
> Some of the ceratopsians have the "run like hell" gene.  Some of them have
> the "turn and defend" gene.  Now who do you think will be passing their
> genes to the next generation?  Natural selection will ALWAYS favor "run
> like hell."  If the ceratopsian cannot flee, then of course it will defend
> itself however it can.  But it will always go for the flight option first.
> Triceratops horridus did only one thing when it saw, heard, or smelled
> Tyrannosaurus rex.  It ran like hell.

And are you familiar with the concept of kin selection?  All of a sudden
we have good reason for half the heard to pound the rex into the
ground.  Presuming, of course, that they have close kin running like
hell.
 
> Some have made much of the dangers of large theropods falling.  This is
> supposed to limit their ability to grapple with large prey.  I agree that
> the danger is there.  I also feel strongly that some have underestimated
> the sense of balance these animals had.  Think of how difficult it would be
> to knock an ostrich over.  Yet an ostrich has only a short, light tail and
> a pair of stubby wings to help it stay up.  Big theropods, with the large,
> muscular tails, must have been absolute masters at staying erect.  This is
> even more true of tyrannosaurs, which could support virtually no weight on
> their forelimbs.

I agree here; it's important to note that the biomechanical laws we're
used to apply to the animals we're used to; dinos are different animals
altogether, and seem to have seriously tweaked laws of biomechanics.
 
> I am less confident about exactly what strategy tyrannosaurs used to kill.
> Tom Holtz and others have suggested that they fall into the pursuit and
> bite category, typified by large canids.  But it is difficult for me to
> envision a tyrannosaur-ceratopsian chase through forest.  I find it more
> plausible that large theropods used a Komodo dragon type strategy, waiting
> along animal trails and lunging out at their prey as it passed by.  They
> slashed horrific wounds, then followed their prey until it succumbed.  I
> believe the reason tyrannosaurs are so gracile is that it does little good
> to slash a ceratopsian and then track down its corpse if someone else gets
> to it first!  This is exactly the problem Komodo dragons face.  Having
> cursorial adaptations allows you to move quickly at greater energy
> efficiency, thus reaching your kill before the other tyrannosaurs can.  I
> believe this is what drove selection for cursorial adapations in tyrannosaurs.

Could be.  I think it likely that Tyrannosaurs used different strategies
for different animals.  The canid strategy might be a good one with
hadrosaurs, but you'd clearly need a different one for ceratopians.  

Chris