Not by Fire but by Ice


 Updated 7 August 2005      

Evidence of  global winter at dinosaur extinction  -31 May 2004  

Rocks in Tunisia reveal microscopic cold-water creatures invaded a warm sea just after the dinosaur extinction.

Researchers studied rocks at El Kef in Tunisia from 65 million years ago, when dinosaurs - amongst other species - vanished from our planet.  

At the time, El-Kef was part of the warm western Tethys Sea . The scientists found two new species of benthic foraminifera - simple animals that live near the sea floor - of cold-water types found in more northerly oceans.

They also found a curious difference in the shape of a microscopic snail-like creature called Cibicidoides pseudoacutus. This creature's shell is said to coil in either a left or a right direction.

In cold waters there are more left-coiling individuals, while this pattern is reversed in warmer waters. The researchers found an increase in left-coiling Cibicidoides, after the K-T boundary.

"It's the first time we have found physical evidence for cooling at the K-T boundary," said Dr Simone Galeotti of the University of Urbino , Italy .

"It must have been dark long enough to cool the oceans," said Matthew Huber of Purdue University in Indiana, "but not long enough that the whole planet iced over."

This impact-induced darkness would have lasted between one and ten years on land, but there is evidence for a cooling of up to 2,000 years at El Kef.

The results are reported in the latest issue of the journal Geology. 

To see the full article, click here:




Order Book l E-Mail Robert l Q & A l Book Reviews l Plant Hardiness Zone Maps l Radio Interviews l Table of Contents l Excerpts l Author Photo l Pacemaker of the Ice Ages l Extent of Previous Glaciation l Crane Buried in Antarctic Ice Sheet l Ice Ages and Magnetic Reversals l Expanding Glaciers