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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
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