Sentences with phrase «placental mammals arose»

This has led to a dominant theory that marsupials and placental mammals arose in the Northern Hemisphere and over time displaced archaic groups of mammals living on the southern continents, such as South America and Australia, that made up Gondwana.

They turned up at sites on landmasses that once belonged to Gondwanaland — sites where they should not be if placental mammals arose in the northern landmass of Laurasia.

Not exact matches

Earth's four groups of placental mammals likely arose from an ancient southern continent.

Conventional wisdom holds that the precursors of modern placental and marsupial mammals arose toward the end of the Jurassic in the Northern Hemisphere, based on the ages and locations of the earliest remains of these shrewlike creatures, which are characterized by so - called tribosphenic molars.