Re: T. rex vision

[rowe@lepomis.psych.upenn.edu (Mickey Rowe)]

Ken Carpenter attempts to defend "Jurassic Park" (the movie)'s
depiction of Tyrannosaurus as a hunter that needed movement in order
to visually detect prey.  Ken, as an elementary school student I kept
king snakes, bull snakes and a rosy boa.  Currently I share my abode
with several amphibians (anuran as well as urodele), a few fish and
some turtles (God's gift to the world according to John Alroy).  I've
got a pretty good idea what is necessary and/or sufficient to get
these animals to recognize food.  However...  Given all that *you*
know, do you have any reason to speculate that Tyrannosaurus actually
needed its prey to be moving in order to see it?  Given *only* what
you know from examination of fossil bones and the theories of others,
would you bet your life on that speculation the first time you were
confronted with an adult Tyrannosaur?  Alan Grant did both of those
things in the movie, and it is to that that I objected.  I have no
objection to the suggestion that movement was important to Tyrannosaur
vision.  I do object to the dogmatism in Grant's "knowledge" of it.

>    That the motion of prey is important to predators is demonstrated
> by new born fawns or baby ground birds who sit motionless if danger
> lurks.

I'll see that fawn and raise you a fish.  In my lab we take advantage
of the fact that when sunfish see something that "frightens" them,
they not only stop all external movement, but they actually stop their
hearts from beating.

-- 
Mickey Rowe     (rowe@lepomis.psych.upenn.edu)