A member of EquuSearch — one of the volunteer groups — said they did not check the wooded lot at the edge of the outlying suburb in early September because it was submerged from heavy rains. When they returned in November, the site had been fenced off.
EquuSearch volunteer Deborah Smith said she believed the remains belonged to Caylee.
"I'm glad she was found before Christmas so they can give her a proper burial," Smith said.
Allen Moore, a spokesman for the Orange County jail, said Casey Anthony was told about the discovery. She was placed under psychological observation, not suicide watch, and remains under protective custody. Her attorney, Jose Baez, visited her at the jail for about 90 minutes Thursday.
Forensic experts said it was harder for investigators to identify a child's remains than an adult's, but they would have a few methods to pursue.
Medical examiners would probably look at photos of the child along with the skull, hoping to make a bone structure comparison, said Dr. Lee Jantz, coordinator of the forensic anthropology center at the University of Tennessee.
Dr. Bill Manion, a pathologist and an assistant medical examiner for Burlington County, N.J., said DNA testing could determine an identification even without other DNA from the victim, "as long as we know who the parents are or siblings."