2023-08-17 20:00:36
PABLO SCARPELLINI
The Angels
Updated Thursday, August 17, 2023 – 20:00
A new study from California reveals the dynamics that contributed to the extinctions of animals like mastodons during the Pleistocene.
Artist’s recreation of some of the animals that lived in this region 13,000 years ago
For decades the mystery persisted among the scientific community. What was the determining factor that wiped out mastodons and other mammals during the Ice Age? Now a new study from California appears to have solved the puzzle. It was the effect of man, combined with climate change, that wiped out 70% of large mammals. who once roamed what is now Los Angeles for millennia. They suddenly ceased to exist.
From the La Brea Tar Pits, a science museum in downtown Los Angeles, they have managed to analyze what happened about 12,700 years ago, when the Earth underwent the last significant climate change. The findings, made possible by a new radiocarbon chronology of fossils from the La Brea tar pits, provide insight into the dynamics that contributed to the Pleistocene extinctions and modern ecological change, research published in the journal Science.
“The conditions that led to the late Pleistocene change of state in southern California are recurrent today in the western United States and in many other ecosystems around the world,” write the authors of the study, led by Robin O. ‘Keefe, Professor of Biological Sciences at Marshall University. “The event may be useful in mitigating future biodiversity loss in the face of similar pressures.”
Regan Dunn and Emily Lind display two fossils
Until now it was known that at the end of the last Ice Age about two-thirds of the large mammals on Earth have gone extinct in most regions of the world. The disappearance of these large species coincided with the climatic changes of the late Quaternary and the expansion of the human population in different parts of the planet, unleashing uncontrolled fires that contributed to the end of these large species, mammoths and mastodons among them.
A site in the heart of Los Angeles
O’Keefe and his research colleagues drew on the wealth of the La Brea (Rancho La Brea) tar pits, a scientific treasure trove located in the heart of Los Angeles and just yards from the Los Angeles County Museum of Art and the Los Angeles County Museum of Art. Hollywood Academy Film Museum. The site contains a nearly continuous record of Pleistocene megafaunal occupation of the Los Angeles Basin from more than 55,000 years ago to the Holocene. Until now, what was known was based on fragmentary paleontological records that lacked the necessary chronological precision.
“The importance of this research will resonate for decades well beyond the scientific field,” said Lori Bettison-Varga, president and director of the Los Angeles County Museums of Natural History. “The La Brea Tar Pits are the only place on Earth that has the fossil record necessary to examine the last significant climate change event in this way.”
Lisa Martinez examining a sample
O’Keefe obtained AMS radiocarbon records on 172 megafauna species and developed a high-resolution radiocarbon chronology for the eight most common mammalian species that inhabited southern California 15,600 years ago. They concluded that seven of these species became extinct in the region 12,900 years ago.
The study also manages to evaluate megafauna extinction data at the continental level and human population growth in North America. In addition, records reveal an increase in large-scale fire activity in the regionencouraged by the rise in temperatures and the prevailing drought in that part of the planet.
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