I use a calcium magnesium supplement that I think might be of interest
to this list.  It's put out by a company called Pioneer.  You can
determine for yourself if it is acceptable to your own paleo practice.
Additionally, the company sent me literature on the bioavailability of
their complex as compared to other types of calcium.  Their's showed an
actual increase in bone density in post-menopausal women within a 2 year
period.  The label reads:

"MCH (microcrystalline hydroxyapatite) comes from New Zealand
freeze-dried whole bovine bone of naturally raised animals, free of
herbicides, pesticides, steroid and antibiotic residues, and toxic
levels of lead and other heavy metals"

In addition, the supplement contains"all micronutrients present in
healthy bone" such as trace mineral complex and matrix proteins.
I do not have the phone # to place orders, but you can find out by
contacting the company at Pioneer Nutritional Formulas, Inc., Shelburne
Falls, MA 01370, USA.

I learned from Dr. James to tell you that I am not a doctor, and I am
supposed to probably also tell you that I don't have any interest
financially in this company, nor do I sell water purifiers or  stain
removers, dicers, choppers, toasters and the gizmo that turns your light
off when you're too lazy to get out of bed.(the clapper?)

Judy Genova, cavegirl who is crawling back under her rock now.