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.

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 ...

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 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.

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 ...

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.