I would be negligent if, at this opportunity, I did not at least mention trace fossils. Trace fossils are formed from the solidification of sedimentary depositions under oxygen- deficient, or anoxic, conditions. These layers can later be separated to disclose some behaviors of the deceased. A rare thing among silent stones. This first screening process, or bias, involves location of the organism.
Terrestrial organisms are less likely to be fossilized.
Drier conditions tend not to transport the minerals needed for fossilization. Both environments have decay, scavengers, and erosion that can destroy remaining hard-parts that would other wise be candidates for fossilization. Trees are targeted by bacteria, fungi, molds, ants, and termites. Besides the biological agents which affect a corps, there are mechanical agents as well. Rapid burial is the key in either habitat for fossilization.