You could dig anywhere on earth and find bones. 10X, FDR, the swamp, has nothing to do with the money pit, which they claim to have located and refuse to bring up to the surface with all their multi million dollar equipment. Oh that's right, they gave up looking for the treasure 4 years ago. "Oh that's exciting." "Oh that's important data." No it's not. They are saying it so we will believe it to be true.
Haven't they said in episodes before that animals have fallen into the holes? Even if they hadn't said it, common sense says that at some point in the last 200+ years animals have died on the island and left bones behind.
Not to mention once they started digging serious holes in the last century anything walking by could have fallen in while they weren't working, it's not like they cap the holes when they leave at night
My point was that they air-lifted 10x already and pretended like they were doing it for the first time and 'acted' shocked to find bones, exactly like they did the first time too.