ABSTRACT
The completeness o f the fossil record, defined in terms of the proportion of all species that ever lived and which are known as fossils, is limited by the completeness of the sedimentary record, usually expressed as the proportion of time actually represented by sediments, and by the fact that not all sediments are fossiliferous. Equally, the completeness of the fossil record may also be defined in terms of how accurately we know the relative abundance, geographic or stratigraphic ranges, etc. of the fossils. In practice, however, the degree of «completeness» of a fossil record depends on a predetermined objective, which also defines the type of information required. To construct a faunal list, for example, requires a single identifiable fragment of a fossil; to describe that fossil requires a complete, well preserved individual; to establish its relative abundance requires a large sample of fossils, whereas to determine its geographic or stratigraphic range requires samples from many localities and horizons. Thus, the same data may be complete for one purpose, but incomplete for another. The related, but separate, concept o f adequacy is also defined by the initial objectives, and the completeness of the fossil record may be quite irrelevant to its adequacy. Too often incompleteness has been equated with inadequacy. I f that were generally true, all science would be inadequate since no science is based on complete knowledge.
