PORTLAND, Ore. (KOIN) — An Oregon field research team believes it has uncovered evidence that indicates humans roamed the state at least 18,000 years ago. This could be proof of North America’s oldest human-occupied site yet.

Since 2011, the Bureau of Land Management and the University of Oregon’s Museum of Natural and Cultural History Archaeological Field School have partnered to excavate the Rimrock Draw Rockshelter near Riley, Oregon.

According to the BLM, archaeologist Patrick O’Grady led the team that had a major discovery back in 2012. The archaeologists unearthed camel teeth fragments that were initially hidden by volcanic ash from a Mount St. Helens eruption roughly 15,000 years ago.

The researchers also found an orange agate scraper with bison blood residue in 2012, and an additional scraper later in 2015. Experts with the BLM said the “natural layering of the rockshelter sediments” hints that the scrapers date back even further than the volcanic ash and camel teeth.

After conducting “radiocarbon-dating analysis” in 2018 and again this year, researchers reported a newer discovery: the teeth date back to 18,250 years ago.

“The identification of 15,000-years-old volcanic ash was a shock, then Tom’s 18,000-years-old dates on the enamel, with stone tools and flakes below were even more startling,” O’Grady said of the finding.

Cooper’s Ferry in Western Idaho was thought to be the oldest-recorded archaeological site in the region, according to the BLM. The “Clovis people,” who arrived from Asia and Siberia around 13,500 years ago, have also been considered the first North Americans.

BLM Oregon/Washington Archaeology lead Heather Ulrich said this new evidence has been an exciting development for those in the field.

“Thanks to the partnership with Dr. O’Grady and the University these new dates push our archaeological knowledge of human occupation in North America even farther, perhaps the oldest yet!” Ulrich said.