Re: T. rex vision

[larrys@zk3.dec.com]

Crpntr@ix.netcom.com (Kenneth Carpenter)
>   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. 
> Thus, I do not have problem with the untestable speculation that T. rex 
>used motion in hunting.  I consider it possible, probable and even maybe 
>(your choise of CYA terms).  I do have problem with the rex not being 
>able to smell Grant from a foot away.  Afterall, the olfactory lobes of 
>a T. rex endocast are big.  

Ken, this is precisely the _point_.  'Rex had very well-developed senses
of smell _and_ vision, as far as we can tell - and that is incompatible
with the kind of visual problems JP depicted.  A t'rex that could be
fooled at point-blank range _that_ easily would not have survived long
enough to leave fossils.  This was an important plot point, and it was
explained in the book, but that explanation never made it to the movie.
Nor would most people notice that both raptors and rexes shared the same
arrangement of eyes and would have similar perception.

Predators _are_ more sensitive to certain patterns of motion.  My cat is
not at all intereted in up-and-down motion, but he can't stop himself from
pouncing on horizontal motion.  But if I moved a piece of _meat_ vertically,
suddenly he is interested.  Motion-detection is _not_ the single, driving
mechanism for prey acquisition for anything more complex than a frog - which
was the point the book made and the movie did not.  So now we have burned
into the public conciousness the perception that t'rex hunted just like a
frog.  And even the movie couldn't bother to be consistant about it, they
made much of the vision thing, but when it came time to do the lawyer joke,
the lawyer moved no more than the digger and girl did but the 'rex saw _him_
pretty good.  Like I said, bad research and poor script writing.

regards,
Larry