Why are Australian mammals all marsupial while mammals on other continents are mostly placental?
A) The marsupial anatomy is better adapted to the environments of Australia than is the anatomy of placental mammals.
B) The placental anatomy is better adapted to the environments of North and South America than is the anatomy of marsupial mammals.
C) When the continents separated from one another, marsupials on Australia did not have the placental competitors that were present in the Americas.
D) Marsupials outcompeted the placental mammals in Australia.
E) Australian mammals have a different common ancestor than mammals elsewhere in the world. When the continents separated from one another through continental drift, marsupials on Australia did not have the placental competitors that were present in the Americas. The mix of plants and animals determine the course of evolution.

Question

Quizplus · Accepted Answer

When the continents separated from one another, marsupials on Australia did not have the placental competitors that were present in the Americas, which allowed marsupials to thrive and evolve into a diverse range of species. This is known as the "marsupial takeover" theory. However, there may have been other factors at play as well, such as environmental and ecological differences between Australia and other continents.

Why Are Australian Mammals All Marsupial While Mammals on Other