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Of Fangs and Feces: Unearthing a Venomous Mystery in a Prehistoric Latrine

The fang of a viper – likely a western diamondback rattler – found within a 1,500-year-old coprolite from the Lower Pecos Canyonlands.
Courtesy of Crystal Dozier.
The fang of a viper – likely a western diamondback rattler – found within a 1,500-year-old coprolite from the Lower Pecos Canyonlands.

The rock shelters of the Pecos Canyonlands are an archeological treasure trove, preserving a remarkable record of prehistoric life. Some of those treasures are literally waste: coprolites, fossilized human feces, from the caves have yielded vivid insights into the diets and ritual lives of ancient people.

The rock shelters of the Lower Pecos Canyonlands are an archeological treasure trove. Here, where the Pecos and Devils rivers join the Rio Grande, shallow caves preserved what would otherwise have been lost to time and the elements. Four-thousand-year-old murals, immense and colorful. Tools, textiles, the bones of butchered game. Then, there are archeological treasures that, quite literally, were another man's waste.

Hundreds of coprolites — fossilized human poops — have been recovered from these West Texas canyonlands. In 2018, three Texas A&M PhD students analyzed one such coprolite, more than 1,500 years old. They discovered a “unique gastrological event” — what the researchers identified as “the potential ritual consumption of a viperous snake.”

Dr. Crystal Dozier, now of Wichita State University, was one of three students, along with Elanor Sonderman and Morgan Smith, who undertook the coprolite analysis.

“Imagine this: It's 1969, and you're like, 'Who's going to want all this crap?'” Dozier said. “Which is what it is. It's a totally innocuous cow patty when it's dry. But once you start the rehydration process, it gets back all the properties of being fresh.”

The coprolite was from a site known as Conejo Shelter, near the confluence of the Pecos and Rio Grande. The construction of Amistad Reservoir here, in the late 60s, inundated many rock shelters, and there was a flurry of excavation before the sites were lost. At Conejo, archeologist Robert Alexander unearthed an extensive prehistoric latrine. There were few tools for coprolite analysis at the time, but he trusted future archeologists to make use of what he'd found.

And he was right — coprolites can now yield vivid insights into prehistoric diets.

The students rehydrated the coprolite for two weeks – during which time it recovered the olfactory qualities of a fresh sample. Then they filtered and analyzed it.

Dozier looked for microscopic pollen grains.

“I was surprised and elated that pollen preservation was beautiful,” she said. “We had really excellent data. Even just glancing at it you could see it was dominated by one particular pollen type.”

The pollen was from a yucca flower — the coprolite's “author” had dined on these crunchy blossoms. Other plants were on the menu. The ancient canyonlands resident had eaten desert succulents — lechuguilla, sotol and prickly pear — which had likely been slow-roasted in earth ovens.

There was protein, too. The researchers found the bones and hair of a rodent — perhaps a pocket gopher. The animal had apparently been eaten whole, with little or no preparation.

The findings aligned with previous studies.

“You know, a ton of these coprolites had been analyzed before,” Dozier said, “so we had an idea of what to expect. And most of what we found in that coprolite was expected, until we got to the one thing that was not.”

The team found the scales first, and then the vertebrae — clearly those of a reptile. Then came the surprise: a fang, with the unmistakable venom channel. Its dimensions narrowed the viperous candidates — these were the remains of a rattlesnake, almost certainly a western diamondback.

Southwestern hunter-gatherers are known to have eaten rattlers — after removing their heads, and skinning and roasting them. But eating an entire rattler, including its venomous fangs, is a high-risk proposition. And the ancient West Texan who did it certainly knew the risks.

Dozier and her colleagues concluded they were seeing evidence of a ceremonial, rather than a purely culinary, activity.

And there's cause for that speculation. Snakes figure in rock art here, suggesting their cosmological significance. And across arid North America, Indigenous traditions link snakes with springs and the watery underworld, and with water itself. Hopi Snake ceremonies, the researchers note, culminate with priests holding rattlers in their mouths, to petition for rain and a successful harvest. And images of Aztec ceremonies to the rain god Tlaloc include human figures – with what appear to be rattlesnakes in their mouths.

It's impossible to know the full story behind the “snakey” coprolite, Dozier said. But it shows that haunting clues about the past can come from unlikely sources.

“I think as an archeologist you have to be okay with a little bit of the unknown,” she said. “But I can't imagine it not being a powerful statement, and somehow engaging with the supernatural. What the motive was, I'm not quite sure. But it was a brave move, no matter what way you look at it.”

Drew Stuart is the producer for the Marfa Public Radio series Nature Notes.