Study: Worms show extinction recovery

BOULDER, Colo., Oct. 11 (UPI) -- After a global extinction 65 million years ago that wiped out much of life on Earth, lowly worms were likely the first life to re-emerge, U.S. researchers say.

Researchers at University of Colorado at Boulder studied sediments laid down shortly after an asteroid crashed into the Gulf of Mexico 65.5 million years ago and caused widespread global extinctions, including the demise of big dinosaurs. They found networks of crisscrossing burrows less than 3 inches above the so-called K-T boundary layer marking the impact.

"Fossil burrows provide direct evidence of animal activity that occurred right at that spot, and these burrows are quite extensive," geological sciences Professor Karen Chin said in a CU release Monday.

"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."

Chin said she believes the burrows were probably made within just a few thousand years of the extinction event.

While some vertebrates, including birds, snakes, lizards, turtles, fish and small mammals, survived the extinction event, the fossil burrows provide direct evidence of animal activity soon after the event that skeletal fossils cannot show, Chin said

"The fact that the burrows are so close to the K-T boundary is one reason they are so exciting," she said.