During the late Cretaceous period, when the Earth was on its warmest era, the now ice-covered landmass of Antartica used to burn raging wildfires, leaving behind charcoal remnants that scientists took interest of.
These charcoal remnants from fossils plants collected during a 2015-2016 expedition suggest that Antarctica was ablaze 75 million years ago.
"This discovery expands the knowledge about the occurrence of vegetation fires during the Cretaceous, showing that such episodes were more common than previously imagined," said the study lead researcher Flaviana Jorge de Lima, a paleobiologist at Federal University of Pernambuco in Recife, Brazil.
These remnants are the first recorded evidence of a paleo-fire on James Ross Island off the southeast side and near the northeastern extremity of the Antarctic Peninsula, in addition to common wildfires in Antarctica during the Campanian age about 84 million to 72 million years ago.
A separate study in 2015 documented the first known evidence of dinosaur-age wildfires in West Antarctica, where macroscopic charcoal remains were preserved by volcanic ashes.
The Cretaceous "high-fire" period
During the 2015-2016 expedition to the northeastern part of James Ross Island, an international team of scientists collected fossils of plants that had weathered over tens of millions of years ago. The largest paper-thin pieces of these charcoal fragments were just 0.7 by 1.5 inches, but electron microscope images revealed during scanning that the fossils are likely burned gymnosperms, likely from a botanical family of coniferous trees called Araucariaceae.
Evidence points that the extreme forest fires in the late Cretaceous had been far more documented in the Northern Hemisphere, while several cases in the Southern Hemisphere.
As the supercontinent of Gondwana were breaking up at the time, the ice-free Antarctica had many ignition sources like lightning strikes and volcanic activity, as well as flammable vegetation and high oxygen levels, that helps generate burning fires.
Volcanoes spread fire and devastated Antarctica
Antarctica was once a utopia of green vegetation and flowering plants millions of years ago, but volcanoes filled its landscape that sparked occurrence of vegetation fires during the Cretaceous period, "more common than previously imagined."
Experts say that the once lush forests on James Ross Island that gone burnt may have been fueled by volcanic activity caused by tectonics.
"Antarctica had intense volcanic activity caused by tectonics during the Cretaceous, as suggested by the presence of fossil remains in strata related to ash falls," the researchers wrote. "It is plausible that volcanic activity ignited the palaeo-wildfire that created the charcoal reported here."
"Volcanic activity was also the probable cause proposed for the coal present in the Cretaceous deposits on Nelson Island."
Nelson Island in West Antarctica is the first region on the continent to record evidence of ancient fires.
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