Contra Costa County Sheriff's Department spokesman Jimmy Lee said Tuesday that was the assessment of a forensic expert who performed tests on the fragment recovered last week.
Lee says it is not unusual to recover Native American remains in the area.
But the department has asked the state crime lab to perform DNA tests to determine the bone's age and whose it was.
Investigators discovered the shard in the yard of the home next to the one where Garrido and his wife, Nancy, allegedly held Jaycee Dugard captive for 18 years.
For a brief time in 2006, Garrido took care of the neighboring house while it was vacant and sometimes camped in the yard.
THE JAYCEE LEE DUGARD STORY
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