Essay On Marsupials

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The mammals alive today can be traced back to their origins in the late Paleoziec period. Marsupials are an infraclass of mammals that primarily inhibit South America and Australia. Marsupials are one of the three remaining extant of mammals and has many mammalian characteristics. Molecular data suggests that marsupials are an extant mammal clade from the mammal sub-class; Theria (Van Rheede et al, 2006). Marsupials belong to the Metatheria clade and emerged during the Cretaceous period. They dominate the mammalian wildlife in Australia and predominantly inhabit the southern hemisphere, apart from one species inhabiting North America. Marsupials have 280 extant species (No-wak 1991). They are separated into two separate cohorts; Ameridelphia and Australidelphia. Common marsupials include; kangaroos, koalas, wombats and possums. They are characterised by their distinct pouch, in which they carry their young.
Marsupials have evolved, along with placental mammals, from Therian mammals. Molecular data suggests that Marsupials separated from Eutherian (placental) mammals approximately 90 million years ago. Australia is the main habitat for marsupials, however there are some in South and North America. As Australia separated from
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Evidence from the differences in teeth structure has provided evidence for the differentiation of marsupial and placental mammals. Fossil records have a general consensus that with maturation, marsupial’s third premolars and post canine check teeth are the only teeth to be replaced. This feature is observed in fossils dating back 95-100 million years ago. The analysis of morphological evidence has established a stronger relationship between marsupials and placental mammals than monotremes (Zhe-Xi et al.

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