Evolutionary trends in frogs

Abstract

Fossil evidence concerning the Anura adds guide-lines to phylogenetic interpretations, but in large part evolutionary information has come from comparative studies of moderns. Trends within the Anura, established in different lines, provide an important source of clues for major phylogenetic interpretations. A number of such trends, both osteological and non-skeletal, are analyzed and their phylogenetic implications assessed.Two major lines of development are postulated. One branch includes the notobatrachid-ascaphid and the pipid-rhinophynid sublines. The other major branch includes the advanced frogs with procoelous centra. The advanced frogs were derived from a primitive stock prior to the development of anything that would be recognized as a notobatrachid-ascaphid-opisthocoelan line, rather than from such a line. © 1965 by the American Society of Zoologists.