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Re: Age Abstractions
Delurking for a moment under the mass of DML posts of recent which
seem to come in huge waves.....
I often find dinosaurian remains in Holocene sediments which have
obviously been placed there by erosion of Cretaceous material
uphill. The Hell Creek sediment was removed by wind and water
leaving the heavier bone pieces and parts behind in modern soil
horizons. These have included complete isolated bones of dinosaurian
origin as well as many other species thriving during the Cretaceous.
This reworking process has not been mentioned in the abstract. I
have a classic location of this for any doubters. Go figure,
dinosaur material in obviously modern sediment. If I sieved hard
enough, I would find man made material from the nearby abandoned 1900
ish dug out homestead mixed with dinosaur bones which would perk up
those man living with dinosaurs people. If this horizon lithified
with geologic time, the mixing of fauna might lead to the abstract
below leading to the dogma that man and dinosaur existed together.
My belated and abused point is: Dinosaurian bones are often found
above the Cretaceous boundary that have been reworked into younger
sediments from below by a variety of processes. Was this possibility
discussed in this paper? Are there any "complete" fossils of
articulated bones in the formation? An articulated remain is not
likely to survive any reworking by natural processes (sometimes they
don't survive removal by paleontologists!).
Frank (Rooster) Bliss
On Jun 20, 2007, at 7:02 AM, Jeff Hecht wrote:
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
525 Auburn St., Auburndale, MA 02466 USA
v. 617-965-3834; fax 617-332-4760