The remains of long-extinct predators dating back to the last Ice Age have been unearthed by underwater cave explorers in Mexico.
Among the discoveries was the skull of a short-faced bear known as Arctotherium wingei, a formidable Ice Age predator that weighed around 150 kilograms.
The fossilised remains of wolf-like creatures known as Protocyon troglodytes were also found in the Yucatán cave on the eastern Yucatán Peninsula.
The findings are a coup for researchers, who previously believed both species only lived in South America, not Central America.
“This discovery expands the distribution of these carnivorans greater than 2000 kilometres outside South America,” palaeontologists from East Tennessee State University wrote in the journal Biology Letters.
“Their presence … suggests a more complex history of these organisms in Middle America.”
A collection of ground sloths and an early human, who most likely died falling into the cave some 12,000 years ago, were also unearthed in the same site, known as Hoyo Negro, or Spanish for “black hole”.
According to researchers, that means humans may have been around to interact with the animals.
“The [Hoyo Negro] pit is bell shaped … and served as a natural trap for animals moving through the cave in the late Pleistocene,” the paper said.
“Mammals discovered on the surface of the [cave] floor include multiple ground sloth species … tapirs, sabertooth cats, cougars, gomphotheres, bears, canids and a relatively complete human skeleton.
“In addition, bones and trackways of extinct fauna are known from the upper passages.”
Another skeleton, believed to be one of the oldest genetically intact human skeletons ever found in the Western hemisphere, dating back 13,000 years, was uncovered in the same cave in 2007.
Scientists said the skeleton belonged to a teenage girl, who too may have fallen to her death after venturing into the dark passages of Hoyo Negro.
At the time, researchers concluded that the Ice Age humans who first crossed into the Americas over a land bridge that formerly linked Siberia to Alaska did give rise to modern Native American populations rather than hypothesised later entrants into the hemisphere.