They have found a huge amount of human and animal bones in an ancient lava tube in Saudi Arabia.
The hollowed-out cave, called Umm Jirsan, is an extensive system of lava ducts beneath the volcanic fields of Harrat Khaybar in the northwest of the country, he says Science Alert.
Umm Jirsan stretches for 1.5 kilometers, making it the longest known lava tube in Arabia. Within those vast shadows, the wild creatures have been busy.
Hyenas are believed to have carried the bones for 7,000 years (Stewart et al., AAS, 2021)
In a new study, researchers report the discovery of hundreds of thousands of bones that belong to at least 14 different types of animals, such as cattle, horses, camels, rodents, and more. Y some of those bones are human.
“This 1.5 km long lava tube is filled with hundreds of thousands of beautifully preserved animal remains,” zooarchaeologist Mathew Stewart of the Max Planck Institute for Chemical Ecology in Germany said on Twitter. Science Alert.
They think they were hyenas
“But why?” According to the researchers, this huge horde of bones was probably kidnapped by striped hyenas (Hyaena hyaena), whose own skeletal remains were also found in the cave, along with its fossilized excrement (called coprolites).
“These critters are avid bone gatherers, transporting them to dens to be eaten, fed to young, or stored,” explains Stewart, noting that the epic assemblage represents a collection for all ages.
“The material in Umm Jirsan has accumulated over the last 7,000 years, which attests to the excellent conditions for the preservation of the bone within the lava tube “.
Hyenas are avid bone gatherers (Stewart et al., AAS, 2021)
While animal bones have been unearthed in the Umm Jirsan lava tube prior to this, there is still much we don’t understand about the taxonomy of the species in the cave, nor what those remains might tell us about the paleoecology in the region, Explain Science Alert.
This old hyena den, however, is not just a relic of the ancient past. During a previous investigation of the lava tube in 2007, researchers heard sounds of “grunts” in the cave, suggesting that Umm Jirsan is still open.
The tip of the iceberg
Other types of animals may have gathered the giant bone collection, such as foxes or wolves. But the team says the weight of evidence points to hyenas: wolves don’t typically disperse bones far from places of death, and foxes can’t easily transport or consume such large prey.
In addition, many of the marks on the bones suggest digestive and hyena bite, Explain Science Alert.
The hyenas used the cave as a maternal den (AFP).
“Taken together, the large ensemble size, the overabundance and intensive processing of the hoofed limb bones, abundant hyena coprolites, and the presence of juvenile hyena and human cranial remains suggest that Umm Jirsan served primarily as a den of striped hyena and , sometimes, like maternal lair“, the researchers write in their study.
While there is still much we do not know about Umm Jirsan, researchers are hopeful that this eerie tomb can serve as a time capsule to shed light on the palaeoecology and prehistory of ancient Arabia, says Science Alert.
“In a region where bone preservation is very poor, sites like Umm Jirsan offer an exciting new resource. This study is just the tip of the iceberg,” says Stewart.