What are metatherian mammals?
Part A Question1) What are metatherian mammals? What are distinguishing characteristics of metatherian mammals?
Extinct mammals, they are very few living. Metatherians, which comprise marsupials and their closest fossil relatives, were one of the most dominant clades of mammals during the Cretaceous and are the most diverse clade of living mammals after Placentalia. The only living metatherian mammals are the marsupials. There were some extinct metatherians that were not marsupials, such as the Sparassodonts, but as these have gone extinct, a metatherian is now just a synonym for a marsupial Metatherians belong to a subgroup of the northern tribosphenic mammal clade or Boreosphenida. They differ from all other mammals in certain morphologies like their dental formula, which includes about five upper and four lower incisors, a canine, three premolars, and four molar. In metatherians, marsupium is present which is required for carrying the infants