Katherine Kinnison said she was going to paint near Linda Lane Beach, just north of the San Clemente Pier, when she noticed something unusual sticking out of the sand.
"I knew that it looked familiar, but I was like it doesn't look like a shark or anything that I've ever seen on the beach before," Kinnison said.
A photo she took shows the jawbone with teeth still attached. She said the more she examined it, the more convinced she became that it might be human.
"I was looking at it for a couple of minutes and then I was looking at it, and I was like 'Oh, maybe I'll leave it.' And I was like wait, no, actually it's pretty cool, and I was like I should take a picture and then the more I looked at it I was like, 'It looks really familiar. It feels like it's human,'" she said.
Kinnison did not touch the remains. Instead, she walked to the nearest lifeguard stand to report what she found.
According to the Orange County Sheriff's Department, the coroner division confirmed the remains are human and are believed to be of Native American ancestry. The area was historically inhabited by the Juaneño Band of Mission Indians.
After determining the remains were not connected to any active cases, the Sheriff's Department transferred them to the Native American Heritage Commission, which is responsible for identification.
Back on the beach where she made the discovery, Kinnison said she hopes experts can learn more.
"I hope that we can maybe figure out if it's male or female, how old it was, or if there's any way to link it, if they knew anything more about the people at that time," she said.
The Sheriff's Department said findings like this are not unusual. In the past year, similar items have been found near Orange County beaches.