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Re: Age Abstractions
This abstract IS notable for having the longest title I have ever seen for
a publication...50 words! It is pretty much an abstract in its own right!
Division of Resource Management
Petrified Forest National Park
P.O. Box 2217
1 Park Road
Petrified Forest, AZ 86028
(928) 524-6228 x262
"Jerry D. Harris"
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Sent by: Subject: Age Abstractions
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OK, so it's just an abstract (so far, not counting all that's been
on the topic previously), but:
Fassett, J.E. 2007. The documentation of in-place dinosaur fossils in the
Paleocene Ojo Alamo Sandstone and Animas Formation in the San Juan Basin of
New Mexico and Colorado mandates a paradigm shift: dinosaurs can no longer
be thought of as absolute index fossils for end-Cretaceous strata in the
Western Interior of North America. New Mexico Geology 29(2):56.
ABSTRACT: Extensive geochronologic studies of the rocks adjacent to the
Cretaceous-Tertiary (K-T) interface in the San Juan Basin have now provided
compelling data attesting to the Paleocene age of the dinosaur-bearing Ojo
Alamo Sandstone in New Mexico and the Animas Formation in Colorado. These
data consist of radiometric age determinations for Cretaceous strata
underlying the K-T interface and palynologic, paleomagnetic, and
evidence attesting to the Paleocene age of the strata above the K-T
interface. The identification of the paleomagnetic normal interval - C29n -
in the dinosaur-bearing lower part of the Ojo Alamo Sandstone in the
southern San Juan Basin at multiple localities allows for the precise
of the last occurrence of Paleocene dinosaurs at the top of chron C29n at
The conventional wisdom (entrenched dogma) among most geologists, and
especially among vertebrate paleontologists has been, for more than 100
years, that all dinosaurs became extinct at the end of the Cretaceous.
dinosaur bone found in place in a formation provided indisputable evidence
that the formation was Cretaceous in age. Now, with the discovery of
Paleocene dinosaurs, the paradigm of Cretaceous-only dinosaurs must shift.
Let us hope that this paradigm-shift will be a smooth and placid
lateral-slip along planar fault blocks rather than a grumbling, rumbling,
herky-jerky sliding of jagged-edged, opposing sides past each other.
must always be conservative and accept such paradigm shifts only on the
basis of the most solid evidence, however, when the data do finally speak,
the shift must be accepted by all of us who follow the data in the noble
pursuit of finding out how the world was made.
I'd've thought he'd put out a press release...?!?
Jerry D. Harris
Director of Paleontology
Dixie State College
225 South 700 East
St. George, UT 84770 USA
Phone: (435) 652-7758
Fax: (435) 656-4022
"Trying to estimate the divergence times
of fungal, algal or prokaryotic groups on
the basis of a partial reptilian fossil and
protein sequences from mice and humans
is like trying to decipher Demotic Egyptian with
the help of an odometer and the Oxford
-- D. Graur & W. Martin (_Trends
in Genetics_ 20, 2004)