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T. rex the Hunter
Let me begin by saying that I greatly respect John R. Horner, but disagree
with his characterization of _Tyrannosaurus rex_ as being primarily an
obligate scavenger. I am only commenting further on this subject because I
have new information to bring to the discussion.
The latest _Prehistoric Times_ magazine, issue No. 27, includes a two-page
interview with John R. Horner, wherein he discusses _Dinosaur Lives_, "_T.
rex_ on Trial" (the new _T. rex_ as scavenger exhibit at the Museum of the
Rockies), _Jurassic Park_ and its sequel, and future exhibits and research.
Within the interview, I am surprised that John Horner should say the
"There is also a duck-billed dinosaur that was apparently bitten in the
tail by a _T. rex_, and again I haven't a clue why that would preclude _T.
rex_ as a scavenger."
I would presume that he is speaking of the _Edmontosaurus_ (DMNH 1493)
which features _healed_ bones along the back of the tail, so the healing of
the wounded bone is, of course, the reason why this specimen is considered
to provide evidence of hunting on the part of _T. rex_. If Horner has been
apprised of the nature of this specimen, what has led him to his point of
view regarding its pertinence to the debate?
One of Horner's main arguments concerns the use of smell in locating food.
He states: "Also, _T. rex_ had a huge olfactory lobe in its brain, which is
an organ for smelling (sic), and the size of it suggests that _T. rex_
could smell things far in the distance, which is only advantageous if what
you are after isn't going anywhere."
In the past, John Horner has frequently invoked the analogy of the 3-pound
turkey vulture, one of the few birds with a good sense of smell (the kiwi
being another). I propose a different modern analog: the 53-ton sperm
whale! It is the largest extant predator (excluding filter-feeding baleen
whales, which clearly don't compare with theropods at all), and, wouldn't
you know it, it has the largest olfactory organ of any known animal, living
or dead! Unlike the tyrannosaurid, it is a swimming animal, but, like a
tyrannosaurid, it has no forearms and grabs prey with huge jaws which are
studded with robust teeth (although, unlike a tyrannosaurid, the whale only
has teeth on the mandible). A recent National Geographic special, called
"Sea Monsters: In Search of the Giant Squid," displayed a computer graphic
illustration of the whale's internal anatomy, and computer graphic
animation showing how the whales might pursue and catch giant squids.
If anyone is interested in further on-line resources concerning the _T.
rex_-as-scavenger debate, there are "Tyrannosaur Hunting Techniques" and
"Gracility and speed of _T. rex_" (both from Thomas R. Holtz, Jr. e-mail
circa 1995), and the recent "_Tyrannosaurus_ the Cannibal" at Jeff's
Journal of Paleontology, <www.dinosauria.com/jdp/jdp.htm>. We can also
look forward to Mr. Holtz' talk at Dinofest.
Jack Horner's hypothesis is on view at
<http://montana.edu/wwwmor/trex.html>, which profiles the "_T. rex_ On
Trial" exhibit. When the Museum of the Rockies site is fully operational,
there is the promise of a John Horner cartoon!
Again, I respect Mr. Horner and his considerable body of work, but I
disagree with him on the above issue.
Ralph Miller III <firstname.lastname@example.org>