page_title: Monito del monte
section_title: Phylogeny and biogeography
hierarchical_section_title: Monito del monte / Phylogeny and biogeography
caption_attribution_description: English: Phylogenetic tree of marsupials derived from retroposon data. The tree topology is based on a presence/absence retroposon matrix (Table 1) implemented in a heuristic parsimony analysis (Figure S3). The names of the seven marsupial orders are shown in red, and the icons are representative of each of the orders: Didelphimorphia, Virginia opossum; Paucituberculata, shrew opossum; Microbiotheria, monito del monte; Notoryctemorphia, marsupial mole; Dasyuromorphia, Tasmanian devil; Peramelemorphia, bilby; Diprotodontia, kangaroo. Phylogenetically informative retroposon insertions are shown as circles. Gray lines denote South American species distribution, and black lines Australasian marsupials. The cohort Australidelphia is indicated as well as the new name proposed for the four “true” Australasian orders (Euaustralidelphia). doi:10.1371/journal.pbio.1000436.g002
context_page_description: The monito del monte or colocolo opossum, Dromiciops gliroides, also called chumaihuén in Mapudungun, is a diminutive marsupial native only to southwestern South America. It is the only extant species in the ancient order Microbiotheria, and the sole New World representative of the superorder Australidelphia. The species is nocturnal and arboreal, and lives in thickets of South American mountain bamboo in the Valdivian temperate rain forests of the southern Andes, aided by its partially prehensile tail. It eats primarily insects and other small invertebrates, supplemented with fruit.
context_section_description: South American marsupials have long been suspected to be ancestral to those of Australia, consistent with the fact that the two continents were connected via Antarctica in the early Cenozoic. Australia's earliest known marsupial is Djarthia, a primitive mouse-like animal that lived in the early Eocene about 55 million years ago (mya). Djarthia had been identified as the earliest known australidelphian, and this research suggested that the monito del monte was the last of a clade that included Djarthia. This relationship suggests that the ancestors of the monito del monte might have reached South America by back-migration from Australia. The time of divergence between the monito del monte and Australian marsupials was estimated to have been 46 mya.
  However, in 2010, analysis of retrotransposon insertion sites in the nuclear DNA of a variety of marsupials, while confirming the placement of the monito del monte in Australidelphia, also clarified that its lineage is the most basal of that superorder. The study further confirmed that the most basal of all marsupial orders are the other two South American lineages (Didelphimorphia and Paucituberculata, with the former probably branching first). This conclusion indicates that Australidelphia arose in South America (along with the ancestors of all other living marsupials), and probably reached Australia in a single dispersal event after Microbiotheria split off. Fossils of another Eocene australidelphian, the microbiotherian Woodburnodon casei, have been described from the Antarctic peninsula, and fossils of a related early Eocene woodburnodontid have been found in Patagonia.
caption: Phylogenetic and biogeographic position of the monito del monte relative to other extant marsupials
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