Hi Seth,
Ivory was always in short supply and expensive. For the longest time during the early Renaissance, France had a virtual monopoly on the ivory carving trade. Baldassarre Embriachi, originally from Genoa, realized that common cow bone was cheap, available, could be carved, and did not yellow like ivory. He began a very successful business making boxes and accessories with carved bone decoration. Carving and inlaying cow bone took off and quickly supplanted ivory in volume of trade. The German stock decorators used it extensively and much that is labeled as "staghorn" is really cow bone, although they used real staghorn as well. Probably any of the bone like decoration that remains really white in color is cow bone. I attached a photo of one of Embriachi's little bone decorated caskets.
dave