Where have all the skeletons and teeth gone?

Answer

Dear Joe

You might not think it, but bones and teeth are not very resistant to biodegradation and chemical weathering on and in the soil. The decomposition process starts immediately after the death of an organism, first the soft parts and then also the harder ones. There are organisms that see a meal in everything that living nature produces, including bones that are full of nutrients. Bone marrow, for example, is not to be sneezed at for some scavengers, but to get to it, the bones must be broken or tapped. Due to scavengers and numerous microorganisms, most bones therefore already begin to disintegrate at the surface of the earth.

If bones and also teeth are buried under the earth, the decomposition process does not stop: in moist and especially acidic soil, decomposition can proceed quickly. The soil is also full of microorganisms that accelerate the decomposition process.

Yet paleontologists do find fossil bones in some places. These are usually bones that have escaped the decomposition process, for example because they ended up under a thick layer of sediment soon after the death of the animal, such as in the vicinity of a river during a flood. Cut off from the oxygen in the air, the chance of storage in such a sediment is much greater. Clay-rich sediments in particular offer good chances of long-term preservation of bones. Ice and permafrost are also ideal for slowing down the decomposition process considerably, so that even soft parts of animals (eg mammoths) can be preserved for a long time.

Teeth and molars are more resistant to biological and chemical degradation than bones because of the hard tooth enamel. Of many fossil vertebrates (large and small) therefore often only the teeth are found, but all in all these are the exceptions to the rule that all remains of vertebrates eventually decay.