Parasites and the fossil record

Parasitologists are fond of alluding to the possible antiquity of their chosen group. They may even place the origin in a specific period of geological time and trace its co-evolution, or lack thereof, with the hosts. These speculations usually make only passing comments on the actual fossil record, but a critical examination suggests that this area can throw much light on both the origins and evolution of parasitism. This review is concerned primarily with the fossil record and its immediate implications. It does not appraise parasite evolution in the light of evidence from sources, often of excellent quality, such as comparative anatomy and physiology or ecology. As some parasitologists may not be entirely familiar with the geological column and time scale, Table 1 depicts these and indicates some records of parasitism mentioned here, together with the major events in this history of life.