Drophyllum leaf plant fossil
June 6, 2014

Remnants Of A 66-Million-Year-Old Forest Fire Found Preserved In Stone

Gerard LeBlond for redOrbit.com - Your Universe Online

Forests affected by fires 66 million years ago during the last days of the dinosaurs recovered no differently than they do today, according to a team of researchers from McGill University and the Royal Saskatchewan Museum.

The team discovered the first fossil-record evidence of forest fire ecology during an expedition in southern Saskatchewan, Canada, at Grasslands National Park in an area known as the Frenchman Formation around Frenchman River. The fossils revealed what the ecology was just before the dinosaurs became extinct and also evidence that the climate was much warmer and wetter than today.

“We were looking at the direct result of a 66-million-year-old forest fire, preserved in stone. Moreover, we now have evidence that the mean annual temperature in southern Saskatchewan was 10-12 degrees Celsius warmer than today, with almost six times as much precipitation,” said Emily Bamforth of the Royal Saskatchewan Museum and the first author of the study.

The Frenchman Formation is a natural configuration that has stood the test of time dating back to the Late Cretaceous Period, an era just before the extinction of the dinosaurs. In this region, fossils of ancient turtles, crocodiles and dinosaurs, as well as the rocks containing the fossilized plants were found.

The fossils were discovered embedded in the region’s rock deposits. “Excavating plant fossils preserved in rocks deposited during the last days of the dinosaurs, we found some preserved with abundant fossilized charcoal and others without it. From this, we were able to reconstruct what the Cretaceous forests looked like with and without fire disturbance,” Hans Larsson from the Canada Research Chair in Macroevolution at McGill University said.

“The abundant plant fossils also allowed us for the first time to estimate climate conditions for the closing period of the dinosaurs in southwestern Canada, and provides one more clue to reveal what the ecology was like just before they went extinct." Larsson added.

The team compared the fossils they discovered to some found without fire damage 125 miles away in a valley called Chambery Coulee. The comparison revealed that the plants were dominated by flora in the same way as forests recovering from fires of today at the Grasslands site. It also revealed plants like alder, birch and sassafras were sprouting during the early recovery of the forest, while sequoia and ginkgo trees were in the mature forests of Chambery Coulee.

Both plant and animal biodiversity can be affected by forest fires and the team’s discovery will help scientists understand the biodiversity immediately before the dinosaurs became extinct. “We won't be able to fully understand the extinction dynamics until we understand what normal ecological processes were going on in the background," concludes Larsson.

Results of this research are published in the journal Palaeogeography, Palaeoclimatology, Palaeoecology.

Image 2 (below): Badlands in Grasslands National Park. Credit: McGill University