ABSTRACT
THE CLASSIFICATION OF PRIMATES with all of its implications for phylogenetic conclusions still rests chiefly on dental and cranial characters and in general not nearly as close attention has been paid to other features. This is most evident in the classification of fossil material of which skulls and teeth have been much more frequently collected, or at any rate described, than other parts. Fossil finds usually represent at best very inadequate samples of a population so that it is impossible to determine whether a given specimen stands near the average of its species or happens to be an extreme variation. The age and sex of fossil fragments are further factors of frequent uncertainty in interpretations. The degrees of variability, of sex differentiation and of the intensity and speed of age changes can differ very widely among primates and certainly need not at all resemble these conditions in recent man, as is tacitly assumed by many anthropologists. It is particularly in the important selection of such features as are most useful for classifying recent and extinct primates that we must constantly bear in mind their variability, ontogenetic change and sexual dimorphism to avoid reaching untenable conclusions.
