Ameridelphia

Orders

The orders within this group are listed below:

• Order Didelphimorphia (108 species)
  • Family Didelphidae: opossums
• Order Paucituberculata (7 species)
  • Family Caenolestidae: shrew opossums

Evolution and phylogenetics

Modern marsupials are now understood to be an originally South American lineage that later reached Australia and diversified there in a massive adaptive radiation. Molecular data, including analysis of retrotransposon insertion sites in the nuclear DNA of a variety of marsupials, and the fossil evidence indicate that Ameridelphia might best be understood as an evolutionary grade. Since Didelphimorphia appears to be the basal marsupial group, it and Paucituberculata do not seem to be closest relatives. Meanwhile, the unranked clade Eomarsupialia has been proposed as the name for the Australian marsupials (Australidelphia minus Microbiotheria, of which Dromiciops is the only survivor), which in all probability derive from a single colonization out of South America via Antarctica.

References

References

1. Schiewe, Jessie. (2010-07-28). "Australia's marsupials originated in what is now South America, study says". [[Los Angeles Times]].
2. Nilsson, M. A.. (2010-07-27). "Tracking Marsupial Evolution Using Archaic Genomic Retroposon Insertions". [[Public Library of Science]].
3. (2014). "The Osteology and Systematics of the Enigmatic Australian Oligo-Miocene Metatherian Yalkaparidon (Yalkaparidontidae; Yalkaparidontia; ?Australidelphia; Marsupialia)". Journal of Mammalian Evolution.