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> I am a grad student at Boston University's science journalism
>program, and I am writing an article on why the age of dinosaurs, and
>subsequently the age of humanity, is constantly under fire. The impetus
>for this article was the 2/25/96 program NBC ran called "Mysterious
>Origins of Man" which claimed, among many other things, that man and
>dinosaurs lived at the same time. Why is this such a point of
>contention? When exactly did scientists nail down the exact age of
>dinosaurs? Why is this so pivotal to the evolution debate? Any thoughts
>or comments would be greatly appreciated.
Glen Kuban and David Schwimmer have already given informative answers
regarding dinosaurs, man, and the Paluxy site. Here's an attempt at a more
general answer to your question.
Earth has a rich fossil record, containing literally billions and billions
of fossils.
Through a set of diverse methods collectively known as "stratigraphy", we
can determine the relative age of fossiliferous deposits. The basic
principles are simple: Overlying rocks are younger than underlying ones,
cut or eroded rocks are older than the rocks that fill in the cut or cover
the erosion surface, etc.
Biostratigraphers investigate fossils of rock successions with known
relative ages. When identical or similar successions of fossils are found
in different places, this is taken as evidence the the different sequences
represent the same time interval. A number of non-biological methods can be
used to add precision and absolute ages (i.e. expressed in numbers of
years) to the correlations.
The scheme that emerges from these studies, though complex in details
(after all, the present biosphere is exceedingly complex, and we're
tracking it through an infinite number of time planes), is beautifully
simple: Earth's multilayered skin of sediments records numerous time
intervals, each of which was characterized by its own, ecologically
differentiated, biota. The greater the time interval between biotas, the
more they tend to differ.
The fossil record shows extensive and successive biotic changes through
time (read "evolution") just as the Apollo pictures shows that the Earth is
round. Evolution is a fact demonstrated by our observations, not a theory.
Theories is what we use to try to explain our observations. The only way to
claim that evolution didn't happen is to ignore or belie the observations.
Creationists and peddlers of tabloid science directly or indirectly imply
that there is a world-wide conspiracy of palaeontologists who knowingly
suppress evidence against evolution, for example fossils in the "wrong"
place such as man-tracks among dinosaur tracks. A cursory survey of
palaeontological literature, however, will show that finding fossils that
"shouldn't be there" is a favourite sport among palaeontologists. To
document convincingly that certain fossils occur where prevailing opinion
says they shouldn't is a sure way to recognition. (On the other hand, a
palaeontologist who doesn't take necessary precautions against
contaminations, misdatings, and misidentifications, not so speak of one
whose discoveries cannot be confirmed, will more or less quickly loose
credence.) The reason no palaeontologists believe that dinosaurs and men
ever lived together is that no even half-plausible evidence that would
bridge the 60-million year gap between their known occurrences has ever
stood up to scrutiny.
The question is hardly "pivotal to evolutionary debate", though, except in
the sense that common misconceptions (blame "The Flintstones"!) have made
it easy to market mirky misinformation such as that regarding the Paluxy
"man-tracks". There are much more crucial and fascinating topics in current
evolutionary debate.
Hope this helps.
Stefan Bengtson _/ _/ _/_/_/ _/ _/
Department of Palaeozoology _/_/ _/ _/ _/ _/_/ _/_/
Swedish Museum of Natural History _/ _/ _/ _/ _/ _/ _/ _/ _/
Box 50007 _/ _/ _/ _/_/_/ _/ _/ _/
S-104 05 Stockholm _/ _/_/ _/ _/ _/ _/
Sweden _/ _/ _/ _/ _/ _/
tel. +46-8 666 42 20
+46-18 54 99 06 (home)
fax +46-8 666 41 84
e-mail Stefan.Bengtson@nrm.se
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