A new study of sediments laid down shortly after an asteroid plowed into the Gulf of Mexico 65.5 million years ago, an event that is linked to widespread global extinctions including the demise of big dinosaurs, suggests that lowly worms may have been the first fauna to show themselves following the global catastrophe.
While the focus on the so-called K-T boundary extinction is often on the survival and proliferation of mammals, paleo-botanical studies show some of the earliest terrestrial ecosystems to emerge were dominated by low-diversity and opportunistic aquatic plants, said University of Colorado Boulder geological sciences Associate Professor Karen Chin. And while sediments laid down immediately following the impact event generally have relatively few animal fossils, new evidence from North Dakota shows networks of crisscrossing burrows less than three inches above the K-T boundary layer.
"Fossil burrows provide direct evidence of animal activity that occurred right at that spot, and these burrows are quite extensive," said Chin, who said their characteristics suggest they were probably produced by worms. "To my knowledge, such burrows haven't been documented in terrestrial environments this close to the K-T boundary. This is a glimpse of a world we don't know very much about yet."
While Chin and her colleagues are still working to understand the timing of the fossil burrows as they relate to the K-T extinction boundary, Chin said she believes that they likely were made within a few thousand years after the extinction event. Future studies should help narrow that window, said Chin, who also is curator of paleontology at the University of Colorado Museum of Natural History.
Chin gave a presentation on the new findings at the 2011 annual meeting of the Geological Society of America being held this week in Minneapolis. Co-authors on the study were A.A. Ekdale of the University of Utah and Dean Pearson of the Pi
|Contact: Karen Chin|
University of Colorado at Boulder