Ancient pollen may prove asteroid not entirely to blame for mass extinction

[Steven Coombs <gasperex@hotmail.com>]

Posted on the Tyrrell website: http://tyrrellmuseum.com/events/#asteroid


Ancient pollen may prove asteroid not entirely to blame for mass extinction

Royal Tyrrell Museum scientist Dennis Braman may have the evidence he needs 
to show diminishing plant life near the end of the Cretaceous Period 65 
million years ago was not just a regional phenomenon, but a continental 
trend.

Braman, a palynologist, recently collected pollen samples from more than 10 
Cretaceous Tertiary (K/T) boundary sites in southwestern Alberta and the 
U.S. that may confirm flora throughout central North America was 
impoverished tens of thousands of years before the asteroid impact that is 
often blamed with wiping out more than half of the world?s plants and 
animals, including the dinosaurs.

The pollen samples will allow Braman to test changes in the relative 
abundance of these ancient fossils before and after the asteroid impact. His 
research has already identified a gradual increase in the extinction rate of 
pollen-bearing plants from samples collected in Alberta along the Red Deer 
River.

Braman believes the K/T boundary sites in Wyoming and North Dakota where he 
collected samples will produce definitive results, but processing the 
samples will take two to three months. What he?s seen, however, corresponds 
closely to the vertebrate fossil record, where there is a gap in the record 
representing as much as 200,000 years where the pollen counts are scant by 
comparison to what scientists know existed earlier.

Braman and other scientists at the Royal Tyrrell Museum are collecting data 
that challenges the popular theory that singles out the asteroid that struck 
Earth at the end of the Cretaceous as the sole reason for the mass 
extinction marking the end of this period of time. Indications are that 
changes in climate may be partially responsible, but according to Braman, 
there is no certainty to what caused the climate switch.

Braman?s expedition to K/T boundary sites in the U.S. was part of a joint 
project with scientists form Jianghan Petroleum Institute and Nanjing 
Institute of Geology and Paleontology in China. In 2005, Braman and Dr. Don 
Brinkman, vertebrate palaeontologist with the Tyrrell Museum, will take 
their findings to northeastern China to compare North American palynological 
samples with similar fossils in hopes of accurately locating the K/T 
boundary in China.



Steven Coombs
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Steven's Dinosaurs: http://www.stevensdinosaurs.com

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