Marsupials might be the more evolved mammals

[UngulateNerd92]

Mammal evolution has been flipped on its head, according to new research that suggests marsupials are the more evolved mammals.

By estimating how the common ancestor of mammals reproduced and developed, scientists have turned over the longstanding belief that marsupials are more primitive than placentals.

Marsupials have long been considered the intermediate step in evolution between egg-laying and placental mammals, because they give birth to highly underdeveloped young similar to an embryonic state for placentals.

However, new research has revealed 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 might be the more evolved mammals

 

[Dassie rat]

I did my specialist essay on marsupial evolution at college. I had read many times that marsupials are more primitive than placentals, but I realised that in some ways they were more advanced. A female kangaroo can have young at 3 levels: a joey in the pouch and one outside, as well as a blastocyst in a state of suspended evolution. If the pouch young dies or when it leaves the pouch, the blastocyst starts developing again and can enter the pouch soon afterwards. For many placentals, a female that has lost young must wait until the mating season and the young can stay in her uterus for many months.