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Re: Horner & T. rex



Thomas_R_HOLTZ@umail.umd.edu writes

>>>                        I was fortunate enough to go to the dedication of
>>>the T-rex in UC Berkeley today. The guest lecturer was John Horner. 

>Just hoping I get invited as a guest speaker at a hadro function sometime :-(

Don't worry Thomas, your day will come :-)

>>and discuss several dino issues.  Just for fun I showed each of them a
>theropod
>>tooth I found in Montana this summer and asked them to identify it.  A
>Berkeley
>>grad student (supposedly a tooth expert) said definitely Albertosaurid,
>>possibly Daspletasaur.  Another Horner grad student had said the same.
>>Padian declined to venture a guess.  Horner was positive it was a Dromaesaurid
>>tooth.h!

>Just a note: Horner is a hadrosaur specialist.  Having some pretty good
>ideas as to who the Berkeley and U Montana grads are, I'd go with their
>conclusions.

I would too!  Incidently after finishing his talk on his scavenger
theory, Horner surprised the audience somewhat by saying, "I don't
even like T.rex; I don't study them.  I'm interested in hadrosaurs".

>>I took notes during Horner's "T.rex as scavenger" talk; his points are
>>summarized below.  I am still unconvinced, but I now have a much better
>>appreciation for that viewpoint.  His arguments are:
>>
>>      - Predators *need* arms to catch prey.
>>        T.rex arms are too small, with too limited movement to be used
>>        to catch prey.

>Tell that to wolves, Lycaon pictus, and phorusrachids!

Not to mention all the predatory birds!

>>     - T.rex teeth are often found among mono-specific bone bed sites;
>>        implies T.rex was scavenging the mass deaths in herbivore herds.

>So what?  Dromaeosaurid teeth are also found there.  Almost no predator
>(except for some snakes, perhaps) will pass up a chance to scavenge.
>>
>>These are good arguments, but I believe there are good rebuttals to each.
>>Certainly T.rex scavenged opportunistically, but I still don't buy Horner's
>>scavenger-only idea.  I did challenge Jack on a couple of points:
>>
>>1. I asked why T.rex would need stereo vision if it only scavenged.
>>   He said stereo vision is a primitive feature that T.rex just inherited,
>>   although it has no need for it.

>Ummm, no.  Albertosaurus, Daspletosaurus, and other basal tyrannosaurids do
>not show the well developed potential for stereoscopic vision.

Also T.rex's snout was severely pinched to clear the field of vision (Bakker).

-----------
Achut Reddy                     So many fossils... so little time!
achut@sun.com