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Re: Age Abstractions
Jeff,
You've got it. All of the previous people that co-authored with Fassett no
longer agree with him. That was clearly stated to 2006 field trip
participants when we visited Late Cretaceous rocks in San Juan Basin during
the Federal Conference in Albuquerque. Also, I saw Fassett present on this
very topic in Durango, Colorado during 2003 Rocky Mountain Section of GSA.
Two of Fassett's previous co-authors disagreed with him then as well,
claiming the bone had been reworked from older Cretaceous rocks.
Andrew R. C. Milner
City Paleontologist
St. George Dinosaur Discovery Site at Johnson Farm
2180 East Riverside Drive
St. George, Utah 84790
USA
Tracksite Phone: (435) 574-DINO (3466) Ext. 2
Cell: (435) 705-0173
Tracksite Fax: (435) 627-0340
Home: (435) 586-5667
Email: amilner@sgcity.org
Website: http://www.dinotrax.com
"There is no branch of detective science which is so important and so much
neglected as the art of tracing footsteps" -- Sir Arthur Conan Doyle, 1891
----- Original Message -----
From: "Jeff Hecht" <jeff@jeffhecht.com>
To: <jharris@dixie.edu>; "DINOSAUR Mailing List" <dinosaur@usc.edu>
Sent: Wednesday, June 20, 2007 7:02 AM
Subject: Re: Age Abstractions
It's curious that the coauthors of previous papers that Roberto cited have
vanished. Perhaps there's a message there?
At 5:12 PM -0700 6/19/07, Jerry D. Harris wrote:
OK, so it's just an abstract (so far, not counting all that's been
published 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 geochemical 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 dating of the last occurrence of
Paleocene dinosaurs at the top of chron C29n at 64.432 Ma.
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.
Thus, 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. Science 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...?!?
--
Jeff Hecht, science & technology writer
jeff@jeffhecht.com http://www.jeffhecht.com
525 Auburn St., Auburndale, MA 02466 USA
v. 617-965-3834; fax 617-332-4760