Are Marsupials the Most Evolved Mammals?

New research suggests that marsupials are the more evolved mammals, overturning the longstanding belief that they are more primitive than placental mammals. The study analyzed skulls during different stages of development in 22 living mammal species and found that the ancestor of both groups was more similar to placentals than to marsupials, meaning that marsupials have modified their method of reproduction more than placentals have. Marsupials give birth to highly underdeveloped young, which is thought to be a better strategy for living with environmental instability.