Home – Home – Jornals – Russian Geology and Geophysics 2003 number 7

Paleobiogeographical zonation is usually based on a biochorological, or biogeographical, method, which is reduced to mapping of ranges of individual taxa (families, genera, and species), followed by their analysis. No unified nomenclature of biochores is available, because there are no approved rules for paleobiogeographical zonation. The problem of relationship between the rank of biochore and the rank of its indicator taxon has not been solved yet. A common rule is that the rank of a biochore depends on the rank of taxonomic distinctions. The rank Realm corresponds to the ranks Family and Superfamily of endemic taxa in Russian systematics; the criterion for recognizing Subrealms is mainly distinctions of generic level. Realms may be subdivided into Provinces, spatially separated communities whose specific character is determined by species (subgeneric, generic) distinctions. To solve the problem of the rank of biochores, it is necessary to analyze the history of the biota for a long time. It seems reasonable to submit the following hierarchical series of the main biogeographical categories: Superrealm, Realm, Province, with intermediate categories: Subrealm and Subprovince; the term region is for informal use.
The largest biogeographical unit is Superrealm. Only synthesis of areal data on nektonic, benthic, and planktonic groups permits recognition of general biogeographical regularities and, therefore, makes the paleobiogeographical division more objective. First of all, this is true for Superrealms and Realms. Recognition of a biochore should rely first of all on a certain chorotype. Chorotype can be that part of a biochore where its taxonomic originality is highlighted. The time of existence of the chorotype (chronotype) must also be provided. The rule of priority name is required.
Biochores are to be accompanied with certain information. The chorotype designation should be supplemented by the name of the first author(s) who proposed the biochore, initial time for which it was established, its territory; paleontological description; additions introduced into these attributes in subsequent publications. The present paper reports examples of description of some chorotypes.