THE PROBLEM OF TRANSITION IN PALEONTOLOGY

The author equates paleontology and phylogeny and discusses principles and problems of transitions found in the phylogentic approach to taxonomy. opics discussed include: subspecies and species (time needed for new species to become isolated is 500 to 1,000 years); the morphological exclusiveness of genera in the differential diagnoses of species, evolutionary patterns of transition in time, the biogenetic law (“Ontogenesis in compressed form reflects the phylogeny of a long series of ancestors, retaining everything that was especially useful for life, but preserving in it generalized form, without the details characterizing the adult states”); ability of changes in early ontogenetic stages to produce sudden large phylogenetic changes, and monophyletic and polyphyletic evolution. — R. S. Boardman.