Allen Thomson on this subject in a late number of NATURE induces me again to draw attention to some objections I offered to the placental classification ... from other mammals; but his names ...

A mammal is an animal that feeds its young milk. The ones that give birth to well-developed babies are called placental mammals. We are placental mammals and so are dogs, cows and whales.

Australia and South America were isolated from other continents during much of the Tertiary, and marsupial mammals thrived and diversified there, while placental mammals took over similar roles on ...

Marsupials have split from placental mammals about 120–180 million years ago. If marsupials had functional brown fat and its thermogenic protein, it would suggest that the organ existed before ...