This page is a permanent link to the reply below and its nested replies. See all post replies »
originnone · 61-69, M
The bone material is exchanged with other material over time until the form still exists but the bone is all gone. You can tell the age of the "stone" by looking at the radioactivity emitting isotopes and their concentrations and comparing them to those of naturally occurring radioactive decay chains. That's how we can tell the ages. Museum animals are typically only partly made of real bones, and the rest are manufactured.