ANTARCTICA AS BACKGROUND FOR MAMMALIAN EVOLUTION
Abstract. Since the 1980's, a series of new Cretaceous-Paleogene land mammals has been found in southern continents. They drastically changed the traditional perspective of how mammals evolved all over the world, and particularly, how they evolved in the southern continents. This paper is a pre...
| Main Authors: | , , , |
|---|---|
| Format: | Article in Journal/Newspaper |
| Language: | English Spanish |
| Published: |
Asociación Paleontológica Argentina
2015
|
| Subjects: | |
| Online Access: | https://doaj.org/article/b4cd60062b594b78b32e0410e382c838 |
| Summary: | Abstract. Since the 1980's, a series of new Cretaceous-Paleogene land mammals has been found in southern continents. They drastically changed the traditional perspective of how mammals evolved all over the world, and particularly, how they evolved in the southern continents. This paper is a preliminary evaluation of how much this new evidence contributes to an understanding of the role Antarctica played both in the evolution of mammals in general, and in the evolution of mammals in southern continents, in particular. The only land mammals thus far recorded in Antarctica come from middle to late Eocene beds of the La Meseta Formation on Seymour Island (Antarctic Peninsula). But the land mammals found in southern South America (Patagonia) and Australia, spanning the Cretaceous-Paleogene, strongly suggest that Antarctica was both an important evolutionary center (at least during the Cretaceous-Eocene), and a "stepping stone" between both continents during the Late Cretaceous-early Paleocene. The taxonomic diversification of monotremes in Australia (represented by at least two Early Cretaceous families, which make four families between that time and the Recent), and the oldest marine barrier between Australia and Antarctica (ca. 64 Ma), indicates that monotremes probably originated and diversified in the Australian/ Antarctic sector of Gondwana. The single dispersal (an ornithorhynchid) to the South American sector before or during the early Paleocene, attests to the role of Antarctica as a "stepping stone" between Australia and South America. The immigration of marsupials to the Australian sector of Gondwana must have occurred before 52 Ma. Thus, the "Australian marsupials" probably also diversified in the Australian/Antarctic sector of Gondwana. The available paleontological and biochemical data suggest that species ancestral to some of the present Australian marsupials evolved in Antarctica prior to their entry into Australia. The idea of the Australian/Antarctic sector as the area of origin and diversification ... |
|---|