Researchers have uncovered evidence of what appears to be a prehistoric "quicksand trap" that caused the demise of elephants more than a million years ago.
In a study published in the Journal of Iberian Geology, a team of researchers from institutions in Spain examined an archaeological site called Fuente Nueva 3 (FN3), which is located in the province of Granada in the south of the country.
FN3 is one of the two sites of Orce in the Guadix-Baza Basin dating to the late Early Pleistocene (roughly 2.58 million to 800,000 years ago), which shed light on the first human peopling of Western Europe. Both sites are dated to approximately 1.4 million years and preserve significant numbers of stone tools, as well as cut and percussion marks made with these tools on the bones of large mammals—associated with skinning and butchering activities.
The FN3 site, in particular, includes many skeletal remains of "megaherbivores" like elephants, hippos and rhinos.
"Given the abundance at this site of fossil teeth and skeletal remains of megaherbivores, particularly elephants of the extinct species Mammuthus meridionalis—an ancestor of the woolly mammoth, Mammuthus primigenius, which lived in Late Pleistocene times—[it] was popularly known in the mass media as the 'Orce elephant cemetery,'" study lead author Paul Palmqvist with the Department of Ecology and Geology at the University of Málaga, Spain, told Newsweek.
Intriguingly, some of the large mammal bones also exhibit tooth marks produced by scavenging carnivores.
In the latest study, the researchers analyzed the archaeological layers below the ground, finding that one in particular—which concentrates many of the megaherbivore fossils—appeared to consist of fine and very fine sands. These fine sands, deposited close to a prehistoric lake that once existed in the region, could have functioned as quicksand in the late Early Pleistocene, according to the researchers. The age of this "paleo-quicksand" would be the same as the age of the site—so around 1.4 million years old—according to Palmqvist.
"Paleo-quicksands like the one described in our paper are extremely rare," Palmqvist said.
The study indicates that this natural quicksand trapped large prehistoric herbivores—including the extinct elephant species, Mammuthus meridionalis—because of the significant weight per unit area of their feet.
Analyzing the remains in the layer, the authors propose that the half-sunken carcasses of "megaherbivores," which occasionally got stuck in the quicksand, attracted scavengers. These scavengers included both hyenas and prehistoric humans, which fed on the stricken animals. This is evidenced by the presence of carved stone tools left behind by the humans and hyena coprolites (the fossilized excrement of the animals) that were associated with the megaherbivore remains.
"Quicksand can potentially be a deadly trap for wildlife," the authors wrote in the study. "After an animal sinks into quicksand, the viscosity of the sediment increases due to the separation of the quicksand into two phases: a water-rich phase and a sand-rich phase. This causes an animal trapped in quicksand to sink deeper when it moves trying to escape from the quicksand trap.
"In such an environment, viscosity can reach such high levels that an animal may require a force up to three times its weight to free itself from the sediment," the authors said.
However, while this quicksand would have been a deadly trap for the megaherbivores, the hyenas and prehistoric humans were able to roam the surface of it without risk of sinking.
"Mud entrapment is a relatively common phenomenon today in Africa because elephants and other large mammals venture during drought episodes into drying dams in their quest for drinking water and taking mud baths," the authors wrote.
"Giant naked-skinned animals such as elephants, rhinoceroses and hippos usually wallow in mud to thermoregulate and protect themselves from insect bites and parasites. However, their huge size poses a risk of being mired in the mud," the authors said.
In the study, the researchers highlight one modern-day entrapment event in which a mother elephant and her calf became stuck in a muddy water hole during the height of the 2019 dry season in Zimbabwe's Mana Pools National Park.
"Eventually, the calf was eaten alive by a pack of spotted hyenas and the mother succumbed days later, probably due to dehydration," they wrote.
The latest study's findings represent a "very important milestone" for our understanding of the subsistence strategies of these early Europeans, shining a light on their competition with hyenas for access to carrion meat, according to the authors.
"It is the first time a natural trap with these characteristics has been described in a fossil deposit of special interest to human evolution," the researchers said in a press release from Spain's University of Málaga.
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Update 07/30/24, 7:36 a.m. ET: This article was updated with comment from Paul Palmqvist and additional information.
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Aristos is a Newsweek science reporter with the London, U.K., bureau. He reports on science and health topics, including; animal, ... Read more
