“Whoa! It's like Spotify but for academic articles.”

Instant Access to Thousands of Journals for just $40/month

Get 2 Weeks Free

New Discoveries of “Opposum-Like” Marsupials from Antarctica (Seymour Island, Medial Eocene)



Five new species of marsupials are described from the middle Eocene La Meseta Formation of Seymour Island, Antarctic Peninsula. Three are derorhynchid didelphimorphians; one species is a prepidolopid polydolopimorphian, and the last is a microbiotheriid australidelphian. Additionally, fragmentary specimens representing an indetermined derorhynchid and a possible marsupial are also described. The prepidolopid and one of the derorhynchids are sufficiently derived as to preclude any close relationship to other members of that family, but the remaining taxa show the closest affinity with species otherwise known only from Itaboraian and older faunas in Patagonia. This differs from the affinity to early Eocene (Casamayoran) taxa shown by the polydolopid marsupials and placental mammals previously known from the La Meseta Formation. The newly described marsupials indicate that the relict La Meseta Fauna is composed of forms that must have dispersed to Antarctica no later than about early late Paleocene, whereas the previously known taxa apparently arrived in the early Eocene. Ecologically, the La Meseta Fauna is composed mostly of small-sized marsupials of likely insectivorous to frugivorous habits and larger-sized placental herbivores. Whereas the ratite bird of the La Meseta Fauna was probably also herbivorous, the phorusrhachoid and falconid birds comprised a large and smaller carnivorous to possibly scavenging component, respectively. Compared to contemporary faunas of Patagonia, the medium- to large-sized marsupial carnivores are lacking in the Antarctic Peninsula. Nevertheless, the La Meseta Fauna is Patagonian in origin and affinity. In conjunction with new faunas of Itaboraian age (early late Paleocene) in Patagonia, the evidence available indicates that from at least Itaboraian time onward the land mammal fauna of Patagonia and northern South America, as well, is a self-contained unit, developing the diversity characteristic of the Paleogene in that continent, including the australidelphian (but South American) microbiotheres. This, in combination with the apparent separation of Australia from Antarctica at ca. 64 Ma, reinforces interpretations that the precursors of the Australian marsupial fauna most likely dispersed from South America to Australia in the late Cretaceous–early Paleocene.



Journal of Mammalian EvolutionSpringer Journals

Published: Dec 1, 1999

DOI: 10.1023/A:1027357927460

Free Preview of First Page

Loading next page...

You're reading a free preview. Subscribe to read the entire article.

And millions more from thousands of peer-reviewed journals, for just $40/month

Get 2 Weeks Free

To be the best researcher, you need access to the best research

  • With DeepDyve, you can stop worrying about how much articles cost, or if it's too much hassle to order — it's all at your fingertips. Your research is important and deserves the top content.
  • Read from thousands of the leading scholarly journals from Springer, Elsevier, Nature, IEEE, Wiley-Blackwell and more.
  • All the latest content is available, no embargo periods.