STUDIES IN QUANTITATIVE PALEONTOLOGY: I. SOME ASPECTS OF THE THEORY AND PRACTICE OF QUANTITATIVE INVERTEBRATE PALEONTOLOGY

For some time there has been a noticeable trend toward a more strictly quantitative outlook in paleontology. In view of many special circumstances encountered in dealing with fossil material, there is a rather extended consideration here given to the theoretical background of the quantitative method as applied to fossil invertebrates. First there is a consideration of the relations between sampling theory and paleontology. This is followed by a discussion of variability in populations and the problem of inference from sample to population. A consideration is next given to the species concept and a comparison of the units which can be used by the paleontologist to those used by the neozoologist. The problem of distinguishing between two species is then considered, this being done from several aspects. Synchronous species, a source of much difficulty, are discussed at some length and this leads into the problem of geographic gradients or dines. This in turn brings up the subject of infraspecific units and the possibility, and advisability, of recognizing them. There is also a short discussion of methods of presentation of data. The last part of the paper deals with the practical application of these various methods to the study of several representative kinds of invertebrate fossils. Of these, the blastoids are representatives of animals that build skeletons of plates, the pelecypods and brachiopods of those with two valves. There are two general types of spiral shells, that in which the initial portion is not enclosed within the later portion, and that in which it is. The gastropods serve to represent the first type, and the fusulinids the second. It is concluded that quantitative methods are demanded by theoretical considerations and that they are thoroughly usable and practical