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 ...

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 ...

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.

Marsupials used to be considered an evolutionary stepping stone between egg-laying mammals called monotremes, such as platypuses, and placental mammals, such as humans, according to the new study.

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 ...

Trekking into the outback west of Sydney, Australia, Darwin is struck by how different the marsupials here are to the placental mammals of Europe. He gets a close look at the anatomy of a rat ...

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 ...

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 ...

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 ...

Australia has the most diverse collections of living mammals in the world. No other continent has the egg-laying monotremes and the pouched marsupials living side by side with placental mammals.