Science & Tech

Former Student Discovers Fossilized Mammoth Tooth On Waco-Area Walking Trail

Texas A&M agribusiness graduate Art Castillo ’16 donated his find to a nearby museum, where it will remain as a valuable teaching tool for future generations of Texans.
By Luke Henkhaus, Texas A&M University Division of Marketing & Communications October 26, 2022

a photo of a fossilized mammoth tooth sitting on top of some rocks in a riverbed
The herbivorous Columbian Mammoth used its large, strong molars to grind up plant matter while grazing.

Courtesy of Art Castillo ’16


This September, an Aggie’s discovery in a riverbed just outside Waco generated a flurry of interest from local and national media. Now, Art Castillo ’16 says his story is proof that everyday people can make meaningful contributions to scientific research and education.

On a late summer afternoon, the Texas A&M agribusiness graduate and Waco-area roofing contractor set off down a walking trail near his apartment. The paved Cotton Belt Trail southwest of the city runs for about two and half miles, crossing a section of the South Bosque River near its halfway point.

a photo of a hand holding a fossilized mammoth tooth near some water
Art Castillo ’16 holds up the fossilized mammoth tooth he discovered in a riverbed southwest of Waco.

Courtesy of Art Castillo ’16

Stepping off the trail to check out the river, where he sometimes comes to fish for bass, Castillo noticed something out of the ordinary — an oddly-shaped rock sitting in the riverbed, with a strange series of ridges along its surface.

“I pull it out and I start looking at it, examining it, and pieces start falling off in my hand,” Castillo said.

Taking a closer look at the patterns on the object, he realized he had seen something like this before — at the Waco Mammoth National Monument on the other side of the city.

“I’ve seen mammoth teeth at the museum, so I took a picture of it and posted it on Facebook,” Castillo said. “I was like, ‘I’m pretty sure this is a mammoth tooth.’”

His Facebook friends agreed, so the very next day, Castillo made the drive to the north side of Waco to show his find to the staff at the museum. “I didn’t call or anything, I just went up there,” he said.

After speaking with site manager Raegan King, Castillo had confirmation: The fossil was a genuine mammoth tooth, one which probably fell from the mouth of a Columbian Mammoth between 10,000 and 50,000 years ago.

a photo out of a car window showing the Waco Mammoth National Monument sign
The Waco Mammoth National Monument was established in 2015 after a decades-long effort to excavate the fossilized remains of more than 20 Columbian Mammoths found at the site.

Courtesy of Art Castillo ’16

A less-famous cousin of the Woolly Mammoth, the Columbian Mammoth lived in North America for hundreds of thousands of years, coexisting with the continent’s first humans before eventually going extinct around 10,000 years ago.

Standing 13 feet tall and weighing in at about 10 tons, these massive grazers could be found roaming the grasslands of North and Central Texas, using their giant molars to grind up each meal. A mammoth would go through several sets of these molars during its lifetime, King told Temple news station KCEN during a segment about Castillo’s find.

Back in the 1970s, another chance discovery set the stage for the national monument to be established, when two local men stumbled upon a mammoth bone near a stretch of the Bosque north of Lake Waco. Over the next two decades, crews unearthed the fossilized remains of an entire group of mammoths — more than 20 in all. Most are now stored at Baylor University, while many of those excavated after 1990 were left in their original positions for the public to see.

Though it’s not believed that Castillo’s tooth is related to the fossils at the monument site, it’s still an important find — and a welcome addition to the museum. While Castillo could have tried to sell the tooth, he ultimately decided to donate it, giving visitors a chance to see and touch a piece of the state’s natural history.

“To me is was priceless to find something like that. You can’t put a price on it,” Castillo said. “I wanted to donate it so that other people can see it and enjoy it like I got to enjoy it.”

Since then, plenty of people have taken notice of Castillo’s generosity. In addition to the segment on KCEN, he has been highlighted by The Dallas Morning News, PEOPLE Magazine and a number of other outlets.

The response online has been tremendous, but Castillo isn’t letting it go to his head. Looking back on the accolades he received from fellow Aggies and others, he simply said, “It was pretty cool.”

Ultimately, Castillo just hopes that others can learn from his example and realize that you don’t have to be an expert to contribute to science and education. Sometimes all it takes is a sharp eye.

“Be adventurous,” he said. “And always look to find something.”

Media contact: Luke Henkhaus,

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