Regan Dunn and Emily Lindsey are two of the authors in a new peer-reviewed study that dissects the disappearance of some large mammals thousands of years ago. (photo by Natalja Kent, courtesy of NHMLAC)

Large-scale wildfires, possibly started by humans, in an ecosystem made fire-prone by climate change caused the disappearance of saber-toothed cats, dire wolves and other large mammals in southern California nearly 13,000 years ago, according to a new study by researchers at La Brea Tar Pits.

Published in the journal Science, the peer-reviewed study breaks new ground in a decades-long scientific debate over what triggered the Earth’s last major extinction event. Supported by the precise dating of fossils preserved at La Brea Tar Pits, the research advances our understanding of the dynamics between dramatic environmental change, human population growth, wildfire activity and the abrupt disappearance of Ice Age megafauna.

“Time series modeling implicates large-scale fires as the primary cause of the extirpations,” the researchers wrote. “We argue that the catalyst of this (ecological) state shift appears to have been mounting human impacts in a drying, warming and increasingly fire-prone ecosystem. This event parallels processes occurring in Mediterranean-type ecosystems today.”

“The significance of this research will resonate for decades well beyond the scientific field,” said Dr. Lori Bettison-Varga, president and director of the Natural History Museums of Los Angeles County. “La Brea Tar Pits is the only place on Earth that has the fossil record necessary to examine the last significant climate change event in this way.”

The museum at La Brea Tar Pits holds the world’s largest collection of fossils from the Ice Age and has been central to the study of animal and plant life at the end of the Pleistocene epoch for more than a century.

Its naturally occurring asphalt pools entrapped and preserved the bones of thousands of individual animals representing dozens of megafaunal species over the last 60,000 years, enabling scientists to determine when different species disappeared from the ecosystem and why.

“The vast collection of Ice Age fossils in Los Angeles opens a unique window on the timing and dynamics of large mammal extinction in Southern California. Going into the carbon dating effort, the team was not prepared for how starkly our data would depict this story, nor for how profound the implications would be,” said Robin O’Keefe, professor of biological sciences at Marshall University and lead author. “There are 19 authors on this paper, and without the contribution of every one of them, the study would not have succeeded.”

For information, visit tarpits.org. The La Brea Tar Pits is located at 5801 Wilshire Blvd.