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 ...

They found that a small, furry, insectivorous mammal was the common ancestor of all placental mammals, including humans. Fossil evidence suggested that the group to which this animal belonged was the ...

The marsupials have a yolk sac placenta (the initial stage in the development of the placenta in placental mammals. In placental mammals, the chorion and the allantois together form the fetal side of ...

Marsupial and placental mammals diverged from a common ancestor more than 100 million years ago, and have evolved independently ever since. The two groups have different modes of reproduction ...

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 ...

By contrast, strepsirrhine primates tend to have brain sizes that are essentially "average" for placental mammals of comparable body mass. Strepsirrhines as a group thus exhibit a range of ...

But the group who found them, headed by Tom and Pat Rich, claim they are true placental mammals. If the Richs are correct, then our understanding of how placental mammals arose and spread around ...

And marsupials solve the immune problem by delivering their embryos early. Recent DNA studies suggest placental mammals began to diverge from marsupials as early as 175 million years ago.