[meteorite-list] More evidence that maybe some (non-bird) dinos survived Chicxlub

From: Darren Garrison <cynapse_at_meteoritecentral.com>
Date: Wed, 29 Apr 2009 00:02:25 -0500
Message-ID: <66mfv4d3lrklg3ob6mfmtjd36msdqkdh6b_at_4ax.com>

Same site, same scientist from the story that broke in 2002. Check below the
article for more links,

http://www.msnbc.msn.com/id/30463774/

Some dinosaurs survived asteroid impact
New evidence suggest dinos stuck around for up to half a million years
        
By Clara Moskowitz

The great splat of an asteroid that might have wiped out the dinosaurs
apparently didn't get all of them. New fossil evidence suggests some dinosaurs
survived for up to half a million years after the impact in remote parts of New
Mexico and Colorado.

The whole idea that a space rock destroyed the dinosaurs has become
controversial in recent years. Many scientists now suspect other factors were
involved, from increased volcanic activity to a changing climate. Either way,
some 70 percent of life on Earth perished, and an asteroid impact almost surely
played a role.

Scientists recently analyzed dinosaur bones found in the Ojo Alamo Sandstone in
the San Juan Basin. Based on detailed chemical investigations of the bones, and
evidence for the age of the rocks in which they are found, the researchers think
some dinosaurs outlived the crash that occurred 65 million years ago and stuck
around for a while.

"This is a controversial conclusion, and many paleontologists will remain
skeptical," said David Polly, one of the editors of the journal Palaeontologia
Electronica, in which the research was published today.

Lead researcher Jim Fassett of the U. S. Geological Survey in Santa Fe, New
Mexico went to great lengths to establish when the bones originated.

"The great difficulty with this hypothesis ? that these are the remains of
dinosaurs that survived ? is ruling out the possibility that the bones date from
before the extinction," he said. "After being killed and deposited in sands and
muds, it is possible for bones to be exhumed by rivers and then incorporated
into younger rocks."

To try to eliminate that scenario, Fassett investigated the rocks surrounding
the bones and studied date indicators, such as their magnetic polarity. He said
the evidence "independently indicate[s] that they do indeed post-date the
extinction."

He also found that the dinosaur bones from the Ojo Alamo Sandstone have
distinctly different concentrations of rare earth metal elements than the
deeper, older rocks that date from the time of the impact. This suggests that
it's unlikely the bones originated in that older rock and were somehow relocated
to the more recent, higher level of sediment.

Another piece of evidence seems to support the claim, too. The fossil remains
include a group of 34 hadrosaur bones lying together, which Fassett said are
"doubtless from a single animal." If the bones had been exhumed from the older
rock by a river, they would have likely been scattered in several locations, and
wouldn't be clustered together as they are.

Even if the dinosaur bones do turn out to belong to disaster survivors, there
probably were very few of them compared to their population before the crash.

"One thing is certain," Polly said. "If dinosaurs did survive, they were not as
widespread as they were before the end of the Cretaceous and did not persist for
long."
? 2009 LiveScience.com. All rights reserved.


Link to a web site with the full, 146 page paper:

http://palaeo-electronica.org/2009_1/149/index.html

There's a link at the bottom of that page for downloading a PDF of the paper,
but the PDF was formatted in a way not friendly for viewing (two pages side by
side.) I reformatted the PDF to zoom to page width for much easier reading and
uploaded it here:

http://www.scribd.com/doc/14751248/Paleocene-Dinosaurs

(You need to sign up to be able to download).
Received on Wed 29 Apr 2009 01:02:25 AM PDT