The ecosystems of shallow marine waters - coral reefs, for example - are the most diverse in the modern oceans, and they have probably been so throughout the history of life. And yet they are under-represented in the fossil record. For environments that are rich in life are also rich in the means of destroying it. When a shrimp or fish dies, it is rapidly devoured by scavenging crustaceans or decomposed by bacteria: every trace of the organism is destroyed in the process. In order for a fossil to be left, the dead organism must somehow be sheltered from the grave-robbing crabs, starfish and bacteria that thrive in shallow-water environments. An animal stands a much better chance of being preserved as a fossil in an anoxic deep-water environment, where there are fewer bacteria and almost no scavengers. The fossil record for oxygen-rich shallow waters is much less complete.

LRB 28 June 1990 | PDF Download