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Re: Age Abstractions


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

Tracksite Phone: (435) 574-DINO (3466) Ext. 2
Cell: (435) 705-0173
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Email: amilner@sgcity.org
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"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