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Report from Dino Fest, Part 3




             | Dino Fest was a gathering of paleontologists,
             | paleoecologists, molecular biologists, teachers,
Standardized | students and enthusiasts all interested in
Introduction | dinosaurs. We met at Indiana University / Purdue
             | University Indianapolis (IUPUI) in Indianapolis,
             | Indiana from March 24 through 26, 1994. (A good
             | time was had by all.)
             |
             | This report represents the ideas and opinions of
             | the presenter(s), not this reporter.


Thursday, March 24, 1994
8:55 a.m.

"What the Fossil Record of Dinosaurs Tells Us"
By Peter Dodson (University of Pennsylvania)

Dinosaurs are part of our culture. Dinosaur information is very
accessible by the public. Dinosaurs have a special popularity
with children because children possess this special knowledge
of dinosaurs that many adults do not know. Even pronouncing the
names represents this special knowledge -- something adults
cannot take away from children.

The Dinosaur Society was mentioned as a body of experts who
review dinosaur books for scientific content.

The fossil record is limited. Presently:
     o There are just over 2000 dinosaur skeletons (not just
       isolated teeth or bones.)
     o There are less than 300 known genera.
     o About half of all genera are known from a single
       specimen.
     o Only 20 percent of all dinosaur skeletons are essentially
       complete.

Culturally, the first 150 years of dinosaur discovery was done by
all men with 10 of 13 individuals noted being anglo-saxon. In the
last 20 years, there is only one anglo-saxon and several women
have joined among the important paleontologists.

A new dinosaur is described about every eight weeks with about
six new descriptions appearing every year. The number of valid
dinosaurs has increased by almost 50 percent since 1970. However,
for every 10 good dinosaur names published in the literature,
there are nine more bad dinosaur names. Thus, a warning was
issued: New dinosaurs should not be described and named based on
a single bone or tooth. Yet this is a practice still in use
today. This is bad science and only obscures the literature.

Most dinosaurs are concentrated in stages: the late Triassic, the
late Jurassic and early Cretaceous, and the late Cretaceous.
Dinosaur genera have a limited longevity; they seem to turn over
about every 7.7 million years, which is almost as fast as
mammalian genera. According to one model, it is estimated that
there were from 900 to 1200 total dinosaur genera that ever
lived.

What does the fossil record say about dinosaur extinction?
(Dinosaur extinction is also recognized as a part of popular
culture.) We are culturally predisposed to "big bangs."
Catastrophic extinctions are far more appealing to the media than
gradualist explanations. Yet there is a conceptual problem with
articles written about catastrophic dinosaur extinctions where
the article barely mentions dinosaurs. There is too much emphasis
on the extinction event and too little regard for what the fossil
record has to say about that extinction.

Using a relatively coarse time resolution of time stages
(approximately six million years), we get the impression that
dinosaurs succumbed to a sudden extinction -- the superficial
appearance that they were cut down in their prime. However, using
a relatively fine time resolution of about three million years
(partial time stages) shows that dinosaurs were already in
decline. The number of dinosaur genera peaks in the early
Maastrichtian and dwindles significantly during the last three
million years. Where once they were distributed across the entire
world, now they are found primarily in western North America (a
sort of oasis in a changing world) and genera diversity has
dropped. Dinosaurs were already dying out before any catastrophe
occurred.


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 Douglas E. Goudie                  To know all things is not permitted.
 ac941@leo.nmc.edu                               -- Horace (65 - 8 B.C.)