I use this as a shortcut reference to the types of evidence available for early and middle prehistory. Bones, as in fossil remains of human skeletons, and stones, as in stones that show evidence of having been formed into tools. Most of the references I have for early prehistory are in the “bones” category, but as I work forward into middle prehistory, “Stones” become more important. This should be no great surprise. Since bones are organic material, they are subject to all sorts of processes that degrade them, and it is fairly rare that conditions are right for them to be fossilized. It is also fairly uncommon for the rock layers in which fossils can be found to exposed at the surface; they are often either buried under later deposits, or have been eroded away. Stones are more durable.