I saw a National Geographic special about the discovery of the Australpithecus Sediba in South Africa. That was the species found in a deep cave. The skeletons of several dozen individuals were in this deep cave. The species lived concurrently with others in the Homo genus about 1.9 million years ago. What was noteworthy that the only bones in the cave found other than the Sediba were the bones of one owl. So it was not a lair of a large cat that hauled the victims down there. The scientists would not state it with any surety but that seems to indicate that the Sediba cared for their dead and stashed them in the cave. I could not help wondering as I watched this, if BF stash their dead in caves or lava tubes. It was really a fluke that these bones were even found. Lee Berger, the chief scientist leading the dig, had to recruit small women paleontologists, especially if they have caving experience, because most men could not fit through the passages to get to the cavern location. Berger had previously, with the help of his 8 year old son, found australpithecus bones in a pit. They are very rare and only a few bones defined the species. After that he instructed some local cavers to start looking in caves for bones. A comment was made quite relevant to the lack of BF fossils. There are more scientists examining the bones of human ancestors, than there are bones to examine. They are very very rare.