It was an exciting discovery. In March, a hunter on the O2 Ranch south of Alpine found what appeared to be an ivory tusk in an arroyo bottom. Ranch Manager Will Juett contacted archeologists at Alpine’s Center for Big Bend Studies. They confirmed the find: this was a mammoth tusk.
It’s 6 feet long. And it’s a fragment, missing its pointy tip. The full tusk was likely 8 to 9 feet long, and belonged to a creature that weighed between 15 and 20,000 pounds.
The mere fact of it is impressive, evoking a time when elephants grazed the Big Bend. But could the tusk have other stories to tell?
Bryon Schroeder is director of the Center for Big Bend Studies.
“Everybody wants to know, What's the next step for the mammoth?” he said. “We've got to figure out how to sample the whole thing, just to understand the life history of that mammoth better. And the more that we can do that, the better understanding of this place we’ll have.”
The remains of Ice Age creatures have been found before in the Big Bend. In the 1930s and 40s, Harvard geologists Kirk Bryan and Claude Albritton Jr. used such remains to date soil strata here. Before radiocarbon dating, their technique was applied worldwide.
But few Big Bend “mammoth localities” have been precisely dated. Dating the tusk, Schroeder said, is the first step.
The Spanish famously called the Big Bend “el despoblado,” the unpopulated place, and that notion has died hard. Archeologists have identified sites in the Southwest where ancient hunters killed mammoths and Ice Age bison. No such “kill sites” have been found in the Big Bend. Did ancient hunters avoid the region?
If the tusk’s dates overlap with human occupation, it’s almost certain Ice Age hunters would have followed mammoth into the Big Bend. “Kill sites” here might be buried, or have been overlooked.
But a human connection with the O2 tusk isn’t certain. Mammoth sizes peaked before people arrived in North America. This tusk may have belonged to one of those older, bigger mammoths.
“I think I would say that it's probably 40,000 years old,” Schroeder said. “That’s my guess. It's probably too old for us, but it's old enough to radiocarbon date. But that's from an archeological view, and we're terrible paleontologists.”
In Ice Age research, the Center has partnered with Kansas University, and KU grad student Haley Bjorklund will lead analysis of the tusk. She’ll employ a new technique of “isotopic analysis.”
Mammoth tusks accrued rings of ivory over time, like a tree’s rings. And chemical traces in these rings can reveal what the mammoth ate, and the landscapes through which it moved.
Several years ago, scientists analyzed isotopes in a 17,000-year-old mammoth tusk from Alaska. They reconstructed the creature’s movements across its 28-year lifespan.
Initially, the male mammoth made seasonal rounds, within a discrete range. Like a contemporary male elephant, it probably lived its early life in a matriarchal herd. But at 16, the mammoth began to roam. Having reached sexual maturity, the male was likely ejected from its herd, to wander alone in search of reproductive opportunities. And wander it did. The mammoth traveled across nearly the whole of Alaska, before dying of starvation, in Alaska’s far north.
Did the O2 mammoth roam in a comparable way? Did it graze the plains near present-day Midland? Did it ascend the Chisos? Did it cross the Rio Grande?
With luck, further research could shed light on the journey of the O2 mammoth, enriching our sense of the Big Bend’s deep past.
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