New insights into the demise of megafauna have emerged from an unlikely source: the sticky depths of the La Brea tar pits. Recent findings suggest that colossal wildfires could have played a significant role in driving these magnificent creatures to extinction. Published on August 18 in the journal Science, the research delves into the ecological shifts of the late Pleistocene epoch and their profound impacts on the prehistoric landscape.
Lead author F. Robin O’Keefe, a biologist from Marshall University, paints a vivid picture of the aftermath of such intense fires, comparing it to a desolate wasteland that endured for a millennium. The study seeks to understand the complex interplay between wildfires, human activities, and the changing ecosystem in California following the recession of glaciers during the late Pleistocene epoch.
The focal point of the investigation was the La Brea tar pits, a treasure trove of paleontological treasures in Los Angeles. These asphalt seeps have yielded the remains of numerous large mammals, offering an invaluable record of the creatures that once roamed the region. The study focused on eight prevalent species: American lions, ancient bison, coyotes, dire wolves, Harlan’s ground sloths, saber-toothed cats, western horses, and yesterday’s camels.
By analyzing the collagen protein extracted from 172 preserved bones, the researchers employed radiocarbon dating to pinpoint the time of each animal’s demise. The fossils, dated between 15,600 and 10,000 years ago, became windows into the past.
The team correlated fossil frequency trends with data on pollen deposits from Lake Elsinore, indicators of plant diversity, and historical records of charcoal deposition caused by wildfires. Surprisingly, shifts in all three records aligned with increases in human settlement. Computer modeling supported the hypothesis that human populations expanded around 13,200 years ago.
Around 13,500 years ago, charcoal deposition surged, pointing to an era marked by extensive wildfires. The overlap of pollen and charcoal shifts raises the intriguing possibility that human activities might have ignited these fires, although the precise cause remains uncertain.
Notably, the megafauna record reaches a striking conclusion. All the studied species, except for coyotes, disappeared from the region approximately 12,900 years ago. This aligns with a confluence of factors: a changing climate, drought, vulnerable vegetation, and human-induced fires. As Southern California transitioned from moist woodlands to dry shrublands, the region became ripe for fire outbreaks.
Human populations flourished, their fires transforming the landscape and exacerbating ecosystem changes. The once-thriving megafauna, accustomed to lush environments, struggled to find sustenance amidst the shifts. Human hunting further compounded their challenges, and the culmination of these factors marked their ultimate demise.
Intriguingly, O’Keefe draws parallels between the prehistoric megafauna extinction and the wildfires sweeping through modern landscapes. The echoes of the past provide a sobering reminder of the complex interactions that can shape the fate of species and ecosystems.