Paleontologists have examined teeth of Teleoceras major — an extinct species of rhinocerotid that lived in North America from 17.5 to 5 million years ago — found at the Ashfall Fossil Beds in Nebraska, the United States. Here, more than 100 Teleoceras major individuals at a single water hole died and were entombed in ash from an eruption of the Yellowstone supervolcano.
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Herd of Teleoceras rhinos. Image credit: Jay Matternes / Smithsonian Museum.
Since the discovery of rhinos at Nebraska’s Ashfall Fossil Beds State Historical Park in 1971, researchers have wondered what drew so many animals together in the same place.
Did they converge from far away, perhaps to seek shelter from the unfolding natural disaster of the volcanic eruption with its choking ash?
“We found they didn’t move very much,” said Clark Ward, a researcher at the University of Minnesota.
“We didn’t find evidence for seasonal migration or any evidence of a response to the disaster.”
Ward and colleagues examined ratios of isotopes of strontium, oxygen and carbon in Teleoceras major teeth to track the movements of the long-extinct animals across landscapes.
“By studying carbon in the animal, we can reconstruct carbon in the environment to understand what kinds of vegetation lived there,” Ward said.
“We can use it to reconstruct how wet or dry the environment was.”
“And strontium tells us where the animal was foraging because the ratio of isotopes is related to the soil and supporting bedrock.”
Teleoceras major was a one-horned rhino with a barrel-shaped body and stubby legs like a hippo. Like hippos, they fed on grass.
And like hippos, the researchers think these rhinos spent a lot of time in and around water.
Because of their vast size, they had few predators in the Miocene epoch.
But their calves would have been vulnerable to hyena-like predators called bone-crushing dogs.
Indeed, some of the specimens found at the Nebraska site bear evidence that scavengers removed portions of their carcasses after they died. And ancient tracks from the 45-kg (100-pound) dogs have been found there.
Yellowstone’s enormous volcano has erupted many times over the past 12 million years.
“Ash from the eruption easily would have traveled 1,127 km (700 miles) across what is now Nebraska where it piled up like snow nearly a foot deep in places,” Ward said.
“But windblown ash continued to fall on Nebraska long after the initial eruption.”
“That ash would have covered everything: the grass, leaves and water.”
“Reconstructing how extinct ungulates utilized ancient landscapes provides important context for understanding their paleoecology and sociality as well as the environments they inhabited,” the scientists concluded.
Their paper was published in the journal Scientific Reports.
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C.T. Ward et al. 2025. Enamel carbon, oxygen, and strontium isotopes reveal limited mobility in an extinct rhinoceros at Ashfall Fossil Beds, Nebraska, USA. Sci Rep 15, 11651; doi: 10.1038/s41598-025-94263-z
