MACNBR   00242
MUSEO ARGENTINO DE CIENCIAS NATURALES "BERNARDINO RIVADAVIA"
Unidad Ejecutora - UE
capítulos de libros
Título:
THE HERALDS: CARNIVORES (CARNIVORA) AND SIGMODONTINE RODENTS (CRICETIDAE) IN THE GREAT AMERICAN BIOTIC INTERCHANGE
Autor/es:
PREVOSTI, F. J.; PARDIÑAS, U. F. J.
Libro:
The Origins and Evolution of Cenozoic South American Mammals
Editorial:
Vertebrate Paleobiology and Paleoanthropology Book Series
Referencias:
Año: 2011; p. 1 - 20
Resumen:
During most of the Cenozoic, and until the middle Pliocene when a permanent connection with Central America was established, South America was isolated from other landmasses. Since this connection, and especially during the Pleistocene, several North or Central American mammalian groups invaded South America, and others from South America went to Central and North America. This biogeographic event was called “The Great American Biotic Interchange,” and its beginning can be traced to the Late Miocene and Early Pliocene, when few North or Central American mammals reached South America. Carnivora and Sigmodontinae rodents, or their nearest ancestors, are the only confirmed groups that invaded South America before the permanent establishment of the Panama Bridge, and both possess a great diversity in this subcontinent. The objective of this contribution is to review the early fossil record of both groups in South America, in order to briefly discuss their biogeography, evolution, and diversification. The first records of carnivores came from Late Miocene levels (Huayquerian, ≈ 6-7 Ma) in Argentina and correspond to procyonids of the “Cyonasua group”, followed by small canids and weasels (Mustelidae) in the Late Pliocene, and large canids, felids, otters (Lutrinae), and bears (Ursidae) in the Early Pleistocene. Other immigration event occurred later in the Pleistocene, when new genera or species of Canidae, Procyonidae, and Felidae are recorded. The diversity of South American carnivores is the product of numerous independent immigrations, plus a moderate in situ diversification within some clades (e.g., Canidae, Felidae). The review of the sigmodontine fossil record, especially some North American fossils previously interpreted as Sigmodontinae, suggest that they -or their presumptive ancestors- invaded the subcontinent once, in the Late Miocene. After that the sigmodontines underwent a moderately long period of isolation and low diversification -spent in the northwestern portion of South America- they suffered an explosive radiation that generated a huge number of species and genera, and the main surviving tribes. This goes against the pattern observed in South American carnivores. Differences in body size, distribution range, and trophic position (as well as other related life traits) could explain the contrasting diversification between these groups: in the case of sigmodontines it could be seen as a more positive “species sorting.” Also, the presence of metatherian carnivores when the first lineage of Carnivora invaded South America, could be another explanation for the lower diversification rate of the group