The process of fossilization will only occur under certain conditions. For instance, if you place your dead gerbil in a sandbox and expect it to be unearthed in a few thousand years and studied, you're probably kidding yourself. However, if you carefully buried your gerbil in a peat bog, taking time to guard your loyal friend and fend off hungry scavengers, old Gerby just may end up getting lucky.

Here are a few basic requirements:

1. The remains must be suitable for fossilization. Teeth and bones are generally ideal, whereas tissue will rarely fossilize because it decomposes rather quickly and leaves no time for mineral infiltration.
2. The remains must be buried quickly so that there is little damage from scavengers and natural elements (i.e. volcanic eruptions and violent storms)
3. The material that the organism is buried in must be suitable for fossilization. An environment with low soil acidity which won't eat away at the bone is ideal, as well as a good supply of minerals which will infiltrate and replace the organic matter.

Depending on the circumstances, it can take anywhere from a few thousand to a million years for fossilization to occur, so don't count on seeing your gerbil in a museum anytime soom.