Ok, you can order rib bones from North star bison. I keep them frozen as well as the ferrier's file, I keep both in the freezer between filings. Use the narrow slanted grooved side of the file. Remember to order a good handle with the file, they come without one. With sharp knife take off the outside tissues on the rib till you get down to real bone, now you're ready. I keep in freezer cause the bone starts to smell and no longer taste good if simply kept in the fridge over several weeks. Place file pointing down onto a big cutting board. I recommend bamboo, plastic ones eventually feed you plastic everytime you cut on it. Stroke the rib against the file, up and down. I file off about two tablespoons powder each time, about twice a day. I eat it plain when hungry and wait till I am hungry again till I eat meat and fat. Get a two to three inch paint scraper, preferably chromed or stainless steel to scrape the powder into a pile and then with scraper and spoon scoop it up into spoon like you would with a dust pan and sweeper. I chew it a bit and swallow. Like I said, fresh bone has a yummy taste, indicating to me that my body likes it. Marrow bones can be used, but harder to get off all connective tissue and tendon, plus you have to get all the marrow out, it clogs the file. Oh, and also you'll need a wire brush, the kind used to brush off old paint on houses. Mine is about two inches wide by about five inches long. After each filing, stroke brush in the direction of grooves to dislodge stuck bone filings. I do this before I scrape the board with scraper and include this all at one time. It seems like a little bit of work, but I can do the whole operation in less the four or five minutes. The rib bones have a cartilidge middle that has other nutrients besides the ones in leg bones. If you order from North star, tell Marry that you want them like she did for me, vacuum packed in packages of five or six, and as full length as they can offer them. As mentioned before all carnivores eat bones, and I believe that past paleo peoples ate them too, as did stephason, and any one eating smaller animals like birds, reptiles, rabbits etc. Plus when 'they' scraped out the marrow, they would have as I do scrape out the softer cancellous bone near the knuckle portion at the top or bottom of the bone.