If they were the first to use bone as a stabiliser where are the later examples ?

Bone isn't ideal at all, hence the lack of a precedent , or later examples .

The shape is hardly ideal ,more importantly it's organic , it degrades , as was evident on one of the big bones . The builders knew their materials and would have understood this .
If they needed to do any stabilising there was plenty of ideal material to hand , the same stuff that supported the majority of the other buildings e.g. soil ( with very little organic content to degrade ) , sand and stone .