It's not every day that a backyard becomes a site of archaeological significance, but that's exactly what happened in the Florida Keys.

Last fall, a 61-year-old woman was digging in her backyard when she discovered what appeared to be parts of a human jawbone and skull. At the time, detectives determined that the bones were old - at least 75 years - but that was quite an understatement.

Lab reports that were released last week show that the bones actually dated back about 2,400 years - to the time period of 200-440 B.C. (See the world's oldest human remains, which were found in Israel.)

The bone fragments were apparently pieces of skull, jaw, arm, leg, foot and back bones, and belonged to two adults, one of whom was most likely female. However, investigators found no human artifacts along with the bone pieces, which leads them to believe that the bones didn't originate in the Keys. Instead, they might have been brought into the area along with fill dirt, which was taken from an unknown location in the state.

Archaeologists have known that ancient people lived in Florida during that time period, mostly acting as hunter-gathers and living off the marine resources. However, because of conditions at sea level, not many remains from this period have been found. The bones have been turned over to the Florida Bureau of Archaeological Research, where they will try to determine their source. Talk about a magnificent discovery in someone's backyard!