OK, what gives here? How is it that fossilized bones can contain any DNA. Isn't everything replaced during the fossilization process. I've really got to get out from under this rock more.
There are a number of ways for organic material to fossilize, the most common is by replacement and that is the one everyone is aware of. However, under certain conditions, a type of fossilization called permineralization can occur where the pores and voids are mineralized but some material remains bone. In most cases of this, depending on length of time the fossil is unexposed, even the remaining bone is eventually replaced. With something as recent as North American Equids and Equines many fossils are simply permineralized.
If you are interested, Google on 'Taphonomy'.