Marsupialia (Marsupials)

• Main Author: Croft, David B
• Format: Other/Unknown Material
• Language: English
• Published: Wiley 2021
• Subjects: Antarc*; Antarctica
• Online Access: http://dx.doi.org/10.1002/9780470015902.a0029245; https://onlinelibrary.wiley.com/doi/pdf/10.1002/9780470015902.a0029245; https://onlinelibrary.wiley.com/doi/full-xml/10.1002/9780470015902.a0029245

Abstract There are around 359 species of marsupials found predominantly in Australia and South America. Many are convergent in form to placental mammals, but they differ in reproduction, physiology and behaviour, offering an alternative view on mammalian adaptation and lifestyles to their more diverse placental counterparts. The distinctive characteristics of marsupials are the extremely small size of the neonate, born in a pouch (the marsupium) and undergoing major development supported by the maternal milk supply. The phylogeny of marsupials has undergone significant revision in recent years with advancement in molecular and morphometric analysis and more fossil finds. The Marsupialia is the crown clade of the Metatheria emerging about 66 Ma. They have diversified into most terrestrial habitats including arboreal and scansorial species but not fully aquatic species. Key Concepts The Marsupialia arose in Gondwana about 66 Ma and represent the crown clade of the Metatheria that diverged from the Eutheria in Laurasia around 160–125 Ma. The distinguishing features of the Marsupialia are (1) a pouch (marsupium), which is variable from indistinct to a large sack with a ventral or dorsal opening, (2) an extremely small neonate whose major development is supported by lactation in the pouch and (3) a unique anatomy of the female reproductive tract. The Marsupialia are found in South America (with one species in the south‐east of North America) and Australia, New Guinea and Wallacea. The Australasian fauna is more diverse, and the two faunas are linked by the Microbiotheridae through Antarctica. The Australasian marsupial fauna dominates the placental fauna and occupies all available terrestrial habitats, but there is no aquatic species. The South American marsupial fauna is about 30% of mammals and is typically found in forests and is most diverse in the tropics and includes a semiaquatic opossum. Large carnivores in both faunas are extinct. The conservation status of marsupials is dire with nearly half the ...