Permian anomodonts: Paleobiogeography and distribution of the group

Abstract

In the Late Permian, higher anomodonts, dicynodonts, reached an almost global distribution. The wide distribution makes this group an important tool in Upper Permian biostratigraphy. Three paleobiogeographic hypotheses for the center of the origin and migration pathways of the major anomodont groups are analyzed. Remains of these animals are most abundant in South Africa; however, they are also widespread in Eastern Europe, China, and India; interesting materials come from Western Europe, Madagascar, Central Africa, and South America. Biogeographic distribution of anomodonts supports the hypothesis of two stages in the origin and distribution of anomodonts. At the first stage, primitive anomodonts evolved in the Northern and Southern Hemispheres, forming high-rank endemic groups. At the second stage, dicynodonts, which appeared in the Southern Hemisphere, evolved rapidly; some groups inhabiting equatorial regions gave rise to the second wave of adaptive radiation, with the emergence of oudenodontids and dicynodontids, which secondarily adapted to high latitudes of the Southern Hemisphere, penetrated into the Northern Hemisphere, and formed there new endemic groups of subfamily rank.