Evolutionary pattern of land mammal faunas during the Late Cretaceous and Paleocene in South America: a comparison with the North American pattern

Abstract

Using families, this paper reviews the pattern of mammal fauna changes in South America throughout the late Cretaceous-Paleocene span, comparing them with the changes in North America. Although there are as yet no records of land-mammal fauna of the latest Cretaceous in South America, the unique Alamitian (Campanian-early Maastrichtian?) and the later early Paleocene Tiupampian land-mammal faunas provide eloquent evidence that abrupt changes occurred during this lapse of time. The known late Cretaceous-Paleocene land-mammal faunas of North America show no such abrupt changes. In North America, a major change occurred between the "middle' Cretaceous Paluxian and the late Cretaceous Aquilan. In both North and South America another major change occurred during the first half of the Paleocene, the Puercan-Torrejonian change and the Tiupampian-Itaboraian change, respectively. the physical (and biotic) Cretaceous-Cenozoic South American history is characterized by long periods of isolation (late Jurassic-early late Cretaceous, and early middle Paleocene-Pliocene), alternating with brief connections. This explains why the history of the South American Cretaceous-Present terrestrial biota is characterized by relatively few episodes. -from Authors