What is Metatheria?
Q: What is Metatheria?
A: Metatheria is a group in the class Mammalia which contains the marsupials and the sparassodonts. It is nearly synonymous with the earlier taxon Marsupialia, but it also includes the nearest fossil relatives of marsupial mammals.
Q: Who proposed Metatheria?
A: Metatheria was first proposed by Thomas Henry Huxley in 1880.
Q: What distinguishes Metatheria from other mammals?
A: Metatherians differ from all other mammals in their dental formula, which usually includes five upper and four lower incisors, a canine, three premolars, and four molars.
Q: When was Sinodelphys discovered?
A: The earliest known representative of metatheres, Sinodelphys, is from the Lower Cretaceous of China.
Q: How are Eutheria related to Metatheria?
A: The closest relatives of the metatheres are the Eutheria (also erected by Huxley in 1880). Both are together united as infraclasses in the subclass Theria.
Q: What does Theria contain?
A: The Theria contains all living mammals except monotremes.
Q: How do metatheres give birth to their offspring?
A: During development, metatherians produce a yolk sac placenta and give birth to 'larval-like' offspring. These offspring have underdeveloped rear limbs, and after birth they migrate to the marsupium where they attach to a nipple.
