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To: dinosaur@lepomis.psych.upenn.edu
Newsgroups: sunpro.sci.dinosaur
Subject: Re: T-rex dedication
Distribution: local
References: <199509180654.XAA16095@franc.ucdavis.edu>

wraddatz@wheel.dcn.davis.ca.us (JenniferFWP) writes:

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

I was there too!  It was an absolutely wonderful event.  The T-rex
specimen is AWESOME; I recommend it to everyone if you're in the bay area.
I also got to speak with Horner and the other paleontologists there at length
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!

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.

        - Fast runners have long shin bones compared to thigh bones.
          T.rex has shin, thigh bones of equal length, so it must have
          been a walker (conflicts somewhat with his book, where he allows
          for the possibility of a 25 mph T.rex.)  

        - Predators need good vision, therefore large eyes.
          T.rex had comparatively small eyes, and small optic lobe.

        - T.rex had unusually large olfactory lobe; implies especially
          acute sense of smell.  Only 2 other animals in history ever had a 
          proportionally larger olfactory lobe:  kiwi and turkey vulture,
          one of which is a scavenger.

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

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.

2. I asked how he would explain the recent find where T.rex tooth mark
   was found in a herbivore bone that had healed over, implying the
   dinosaur had escaped and survived a T.rex attack.  His answer was,
   "it's not a T.rex tooth mark".

Still, he made a reasonable case even though he is not as serious about it
as he seems.  In "The Complete T.rex" Horner admits that he is not sure
about the scavenger theory, but he often talks that way when talking to
others, just to take up a contrary position.


> The food was weird(even for Beserk...Berkeley but other

What, didn't you care for the little plastic dinos on every food plate? :-)
Actually I thought the macadamia nut chicken was delicious!

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