Centuries before the advent of housing tracts and highways, Native Americans were making Orange County their home.

On occasion, a reminder of their early ancestors’ presence taps modern civilization on the shoulder, as it did Sept. 25 when a construction crew unearthed bones next to the 405 Freeway.

The find brought excavation to a screeching halt alongside the overpass – one of 18 slated for widening in the $1.9 billion improvement project.

“Work remains stopped in the area while all established procedures are followed,” Orange County Transportation Authority spokesman Eric Carpenter said.

The Orange County coroner’s office established that the bones are human, said Artin Baron, supervising deputy coroner. “An archaeologist determined that artifacts around the bones signify Native American remains.”

FROM 2006: Workers uncover Indian burial site in Huntington Beach

Baron said he does not have information about the artifacts or the age of the bones. “It was not a coroner’s case, so we immediately turned it over to the California Native American Heritage Commission,” he said.

Discovery of Native American remains in Orange County is not unusual, Baron said, occurring at least a couple of times a year.

Officials are tight-lipped about the recent find, made all the more sensitive because Native American remains are protected by federal and state laws.

Calls to the Native American Heritage Commission were not returned. And Carpenter requested that the site’s location not be identified during the investigation.

“OCTA is working with Caltrans, which oversees and ensures that established state procedures are followed,” Carpenter said.

Attorney Dorothy Alther, executive director of the California Indian Legal Services, represents tribes in matters that include the disposition of ancestral bones. Some of her cases have involved Caltrans highway construction in Northern California.

“It’s much easier when you are working with a state agency than a private landowner,” Alther said. “There’s a step-by-step process in place.”

Even in those best-case scenarios, Alther said the process can require two months or so – which translates into a delay for that section of the 405 Freeway widening job.

RELATED: Native Americans, others gather at ancient site south of Orange County to honor the past, and the future

However, OCTA has built flexibility into the five-year project – allowing it, for example, to rearrange the schedule for bridge renovations.

“Any time you start disturbing dirt in California, you’re likely to find artifacts,” Alther said.”It’s the price of doing business.”

Some tribes buried their loved ones with utensils, fishing equipment and other implements. “Funereal objects were intended to help the departed in the next stage of death,” Alther said.

Often, skeletal remains found in California date back thousands of years.

In 2007, the discovery of hundreds of mysterious stones and human bone fragments up to 8,500 years old threw a wrench in the Brightwater Hearthside Homes development in Huntington Beach. Historians say the land was once shared by the Juaneño Band of Mission Indians and the Gabrieleino-Tongva.

After a find, the Native American Heritage Commission contacts “most likely descendants” to inspect the site and determine how best to enshrine the remains “with appropriate dignity” – whether burying them at the original location, perhaps, or on tribal lands.

While they may slow down developments, the procedures are important for treating sacred Native American grounds with respect, said Walter Ahhaitty, operations director for the Fountain Valley-based Southern California Indian Center.

“Otherwise, it would be like going into a cemetery and digging up someone’s grave site,” Ahhaitty said. “It should not be taken lightly. We might not know today where our indigenous people are interred, but they knew and they cared.”