Seals, Sea Lions, and Walruses. A Review of the Pinnipedia

To write a comprehensive book that encompasses, among other things, the structure, habits, evolution and classification of a mammalian order is a rather unique accomplishment. This, however, has been done with admirable skill by Dr. Victor B. Scheffer. The pinnipeds, as a group, are world-wide in distribution although they are limited essentially to continental shores, islands, and polar ice fields in the breeding season. During this critical reproductive period, therefore, their distribution is essentially one-dimensional, comparable to that of alcids among birds, certain fishes and many marine invertebrates. This, as the author suggests, has probably had a marked influence on their evolutionary development. Little is known regarding the origin of the pinnipeds since no fossil remains older than Miocene have, as yet, been found. Nevertheless, three possible progenitors have been proposed by various authors. The Pinnipedia may have arisen from insectivore-creodont stock back in the Cretaceous when cetaceans and sirenians...