Preference for use of taxa. An alternative to the employment of taxa of fossils would be the use for comparison of separate individual characters of fossils for a similar purpose (see Doyle and Riedel 1979); although in such cases an adequate language based on characters alone appears to be feasible, such a construction has not been attempted here. The taxon concept for living organisms is based on observed discontinuities in the scope of studied life. Use of taxa has long been an accepted tradition in paleontology, and continuation of the use of taxa, although in a new form, leads to easier compatibility with past work.

Artificial nature of taxa of fossils. A fundamental premise to the use of taxa of fossils of any style is that such taxa are recognised as being man-made (i.e. artificial). A statistical homogeneity of measured characters may indicate that a fossil assemblage from a single sample approximates to a sector (population) of a species in the sense used for living organisms, but no further or more complete interpretation of a whole taxon is ever possible from such single assemblages of fossils.

The limit of a taxon of fossils in time is determined automatically by the author of the taxon through the detail of the description he constructs (Fig. 6.1); the kind of organism concerned will have been slowly, or even very slowly, evolving and the taxon is in effect a time-slice (of n generations) of the relevant life continuum determined by the parameters in the description selected by the author for the presentation of the taxon.