Os metatheria da América do Sul: uma análise espaço-temporal

Abstract

Metatheria is a clade of therian mammals (Mammalia:Theria) represented by approximately 334 living species, all marsupials distributed in 7 orders: Paucituberculata, Didelphimorphia, Microbitheria, Dasyuromorphia, Peramelemorphia, Notoryctemorphia and Diprotodontia. They are distributed in the Americas, New Guinea and Australia. In South America, the orders Paucituberculata, Didelphimorphia and Microbiotheria occur, the latter belonging to the Australidelphia lineage. The methodology consists of a bibliographical review of the main scientific works related to Paleobiogeography, Paleontology and Evolution of Metatheria in South America, in order to synthesize the knowledge in the literature on the subject and expose the main future challenges for the Paleontology of Metatheria. Metatheria probably originated in Asia, at least 160 million years ago, and during the Cretaceous it dispersed to North America and Europe, where it diversified into new lineages. These lineages later dispersed to South America, probably in the late Cretaceous, where they gave rise to new lineages, including that of the living Australian marsupials. The fossil record of Metatheria in South America comprises the following lineages: Sparassodonta, Polydolopimopimorphia, Paucituberculata, Microbiotheria, Didelphimorphia and basal Marsupialiformes, with a wide diversity of forms and occupied niches. In addition to the fossil collection bias, there is a discrepancy in the record of Metatheria in South America, with most fossils found in paleontological sites located in the Austral region (Patagonia), while the Neotropical region has few records in contrast. Due to the scarce and incomplete fossil record on the continent, the strains present taxonomic and phylogenetic problems, and their place of origin and evolution is quite controversial.