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Re: dino symposium? (long)
Mike Habib gave a great rundown of the Saturday talks (better than I could
have, especially since I missed the morning ones). It'a a shame he missed
Sunday and the roundtable discussion in particular.
Before I get into that I wanted to comment on Elizabeth Rega's talk. I was
extremely impressed by her, enough so to see the error in the ways of Bruce
Rothschild, who is near and dear to my Carnegie heart. She quoted him in
particular when criticizing current paleopathological "diagnoses". His
training is in the medicine of only one (human) animal. Human reactions to
disease and toxins, Rega showed, can be wildly different than those of other
species. If indeed they were not different, making human and veterinary
medicine equivalent, methinks your HMO PCP lists would be full of vets. It
makes me wonder how many pathology studies should be reexamined. Sorry,
Bruce. Physicians are pressured into making a definite diagnosis so that
they may treat the problem. We don't need to do that with fossils, and
perhaps it is inappropriate if we cannot be sure.
By the way, Rega claims the dubious honor of starting the whole "Smelly" T.
rex bit. She seems to have been referring to the pathology, not the
critter. And I'll report this just because she does _not_ want it to be
remembered, though she said it 3 times: dinosaurs might possibly have gotten
gonorrhea. I see an adult version Far Side cartoon in there somewhere.
Horner's keynote address was keyed toward the public, though they were
hardly there. He did an historical rundown of dino paleontology. Jack
noted that today we have lots of info and new specimens (compared to paleo
of years past) but that it is still resulting in many arm-waving
interpretations. And, yes, he confessed to making his share of them. He
also summarized some of the results of his Hell Creek project, noting that
his predator/prey ratio is quite skewed. [10 Triceratops, 8 Tyrannosaurus, 5
Edmontosaurus, 4 Thescelosaurus, 3 Ornithomimus, and 1 Ankylosaurus] By
looking at some of his other current work, he emphasized the need for
testable studies to confirm or discredit the arm-wavers.
The roundtable discussion was of particular interest to me. Matt Carrano
moderated. Considering that it occurred between public-oriented talks, it
should logically have also been on a public audience's level of
understanding. Since virtually no public was in the auditorium, however, it
became an intellectual discussion among colleagues. Average Joe would have
been lost in the barrage of "parsimony" "ontogeny" and "monophyly," to name
the most innocuous terms. Remember that three quarters of American Joes
don't attend college. Think back to what you understood of paleo when you
were 17. Then also remember that Average Joe is not the paleo freak you may
have been at 17.
I applaud the public target for the forum. How often do you get to see so
many worthy speakers in one sitting outside of professional conferences?
For free no less. The Smithsonian did the public a serious injustice in not
advertising this symposium. If they consider doing this type of meeting
again, I hope they realize that the poor attendance was not for lack of
interest, but lack of notification on top of lousy weather. It is unlikely
that any other institution could pull this off and offer it free to the
public. They need to try again next year.
Now that I've vented, here's the play-by-play of the roundtable, at least
what I found significant enough to write down. I should also put in the
disclaimer that Carrano did not introduce the panel, and I missed Saturday
morning's talks. Thus, I may have misidentified those I list as Erickson
and Larsson. Most of the talk focused on the problems associated with
assessing and identifying juvenile specimens and the significance of their
Scott Sampson queried Horner as to the average longevity of a dinosaur
species. Horner quoted the typically given 3 million years, but said that
he knew Scott wanted to address a possible anagenetic event seen within the
Two Medicine Fm. This seemed to have occurred over a 200 thousand year
span. Horner refrained from calling these critters new species -- a new
taxon, yes, but not necessarily a new species.
That moved the talk into problems of what characterizes a species -- Barrett
noting ecological morphotypes can be programmed into the DNA of a single
species, but we can't tell that with fossils.
Horner mentioned the problems with juveniles that all look the same. He
noted that studies done on ontogenetic series are really guesses -- the
postcranials of all hadrosaurs look the same. Sampson agreed and added that
all ceratopsians also look the same. We are guessing that the chosen
specimens are not smaller and larger adults of different species.
This shifted the topic to specifically juveniles...
Wilson noted the need to study the order of epiphyseal fusions in ontogeny.
Erickson brought up the difficulties associated with sexual dimorphism.
Rega noted that dinosaurs might have changed their ecological niches through
ontogeny. She gave iguanas as such an example: they are insectivorous as
juveniles, and herbivorous as adults. Microwear analysis will only give us
the evidence from the last several meals, so we may be making some
Erickson argued that most collection specimens are likely sub-adults, that
the senescent adult would be rare.
Larsson went so far as to say that 90% (!) of collection specimens could be
unrecognized juveniles of other species.
Horner noted that we are probably causing a sampling bias with histological
studies. He claimed that smaller critters are chosen because it's hard to
cut big bones.
Erickson brought up, of course, the taphonomic bias against small critters.
He pointed out that we find many small dino teeth at microsites but we don't
find the corresponding bones.
Horner threw in that the effects of depositional biases add to the problems
as well. The Two Medicine Fm is mostly overbank deposits with almost no
channels, while the Hell Creek is mostly channel deposits with few overbank
areas. The differing energies will preserve different size critters, as
well as different habitats.
Raga believed we have a "huge sampling error". Most living critters have a
huge juvenile mortality rate of 30-50 percent. We should be swimming in
juvenile and sub-adult specimens.
Sampson noted that we have few specimens that display the EFS compact bone
growth lines that indicate somatic maturity.
Larsson suggested we are possibly underestimating diversity because
sub-adults look more like one another. We are lumping when we should be
The topic moved to cladistic method...
Wilson addressed the weighting of characters -- though all characters are
supposedly weighted the same, the way the characters are defined
intrinsically weights them. However, to differentially weight the
characters would only add to the assumptions of relative significance.
Sampson brought up the example of the hominid decrease in prognathism -- one
effect makes 100 changes that would be separately listed as cladistic
characters. Sampson expressed the fear among paleontologists that at some
level "this process [of defining species] is nonsense."
They moved to comparisons with extant critters, one asking how often
neontologists go through a whole population and measure individual variation
(they usually don't). Horner suggested that paleontology is affecting the
work of neontologists -- that, for instance, bone histology work hadn't been
done on modern critters until it was needed for extrapolation to fossils.
But the best quote of the symposium came from Jeff Wilson. "You can't shove
a thermometer up a dinosaur's butt." Thank you, Jeff.
The other talks were about plants and bugs. I won't go into that. I left
before the impact talk due to snow on my route home. But a good time was
had by those few of us who did attend. Hopefully they will do it again
Carnegie Museum of Natural History
Division of Education
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Pittsburgh, PA 15213