An annotated synopsis of paleozoic fossil spores : and the definition of generic groups /

Abstract

This report presents the revised classification of plants identified from their isolated fossil spore coats, and deals primarily with those of Paleozoic age. Orthodox taxonomic procedure has been followed as closely as possible for reasons which are presented in the introduction. A cautious policy has been followed with regard to synonymy, and, even though forms are very closely allied, names based on different holotypes have been allowed to stand. In many instances, however, the apparent close relationship, which may later prove conspecific, has been noted. Thus names noted as synonyms are nearly all objective synonyms because they are based on a common holotype. Many difficult problems concerning nomenclature of fossil plants are solvable if nomenclatural types are strictly interpreted. About 400 named species have been included in the present paper and most of these have been allocated among 23 genera which seem to serve a useful and significant purpose in classification. Additional genera no doubt will require recognition later and new information will modify the views that have been expressed for the genera described here. A number of species described previously apparently do not conform sufficiently to merit inclusion in the same genus with the type species of the group, and at the same time do not show convincing evidence of affinity with other recognized groups. Such forms have been listed as species excludende. Attention is directed to the several species excluded from Reticulatisporites which here is interpreted in a considerably restricted sense. Many of these forms require much more careful study in order to arrive at a satisfactory expression of their affinity and classification. Other forms listed under incertae sedis also are lacking in sufficiently understood biological characteristics to support a definite systematic allocation. In dealing with plant microfossils it seems unavoidable that many forms worthy of description will nevertheless have such problematic relationship that their assignment under incertae sedis is obligatory. The usefulness of fossils nevertheless bears a considerable relationship to the basic and fundamental information available about them and for this reason greatest significance must be attached to species whose relationship has been reliably established. The authors of this paper and their associates have observed many new types of plant microfossils in preparations from coal and carbonaceous sediments in America. The present synopsis is the outgrowth of a need for a more comprehensive survey of previous work considered from the standpoint of a consistent systematic policy. The essential features of an appropriate policy have been embodied here to serve as a working basis for the great amount of descriptive work yet to be done. We believe that this working basis will require further revision as new information is accumulated and presented. We further believe that such revision can be carried out with greatest efficiency and benefit to all concerned if the orthodox usages characteristic of mature systematic science are adopted and critically applied.