[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

RE: Predation in fossil record?



Bruce et al:

Jack Horner likes to be contrary (or at least somewhat controversial).
He often creates some brouhaha, just because he thinks that other people
will need to do better science to prove him wrong.  (I've mentioned
several times his musings [from over a dozen years ago] that all
dinosaurs were born with down feathers.  This was not published, but
Jack liked the idea, and was apparently presenting it to other people to
investigate.  Still a neat idea).  Tom Holtz presented a paper 5 years
ago that addressed each of the points the Jack has raised over the past
half-dozen years.  (Jack was there, and talked to Tom afterwards - He
still didn't agree).  

One of the straw-men that he (Jack) raises is the fact that _T. rex_
couldn't run very fast.  This reminds me of the old joke:  Two guys are
hiking, and they come near to a Grizzly Bear (and disturb it).  Of
course, they're scared, as the bear begins to approach them.  One guy
bends over and starts to tighten his sneaker laces.  The other guy looks
at him and says "Are you crazy?!? You know you can't outrun that bear."
The first guy says "I don't have to outrun the bear.  I only have to
outrun you!"   
_T. rex_ ran faster than most of its prey.  It didn't need to outrun it
by much.  Also, it could be an ambush hunter.  (Jack once joked that
maybe _T. rex_ jumped out from behind a rock, and kicked a _Triceratops_
over!)

Also, the "too-small" eyes are set so that _T. rex_ had binocular vision
(almost always a feature of large vertebrate hunters).  [BTW, I don't
mean that his eyesight magnified his vision, just that it allowed
accurate 3-D spatial recognition.  We have binocular vision].  I wonder
what _T. rex_ used his for?  If he could smell the carcasses that he
only ate (according to Jack), why would he need to see so well?  

The munched Edmontosaur gives evidence to the survival of an attacked
animal.  It also indicates that something sufficiently large attacked
it.  Granted, _T. rex_ and the Edmontosaur did not co-exist.

In addition to the examples that you mentioned, add the dinosaur tracks
that apparently show a carnivorous dinosaur tracking a larger
herbivorous dinosaur (and, in at least one case - several herbivorous
dinosaurs).  Unless the carnivore somehow knew for sure that the
herbivore was going to die very soon, why would it track it? (Unless, of
course, it knew the herbivore would die very soon, because the carnivore
was going to kill it!)   :-)  Fossil trailways are often the best
indicators of actual behavior.

It's possible that Jack Horner won't be satisfied that _T. rex_ was a
predator, until he finds one and a _Triceratops_ in the same position as
the "fighting dinosaurs".  Oh, well...

Allan Edels 

-----Original Message-----
From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu] On Behalf
Of Bruce Woollatt
Sent: Saturday, June 21, 2003 2:34 PM
To: dinosaur@usc.edu
Subject: Predation in fossil record?

Hi all,

The current flap over Horner's " Big Stinky Scavenging T.rex" claim got
me 
to thinking. Apart from the "fighting dinos" and the munched Edmontosaur
who 
lived to talk about it, what other evidence of actual hunting behavior
is 
there in the fossil record? If there were not extant examples of wolves,

lions, tigers (insert name of any predatory animal here) etc., how would
we 
"know" that they hunted at all? How would we know if an animal scavenged

without reference to living examples? Dentition certainly indicates
diet, 
but perhaps not neccesarilly means of acquiring food.  Can these be 
distinguished in the fossilsl?  Much of Horner's assertion for
scavenging 
seems to be based on personal incredulity (arms, eyes seem to him to be
too 
small  to be used for hunting) rather than evidence. I would think that
the 
best you could doin the absence of evidence for a fossil creature's
behavior 
  would be to say you're not able to decide which was used.

Bruce

_________________________________________________________________
STOP MORE SPAM with the new MSN 8 and get 2 months FREE*   
http://join.msn.com/?page=features/junkmail