What are potential hypotheses (explanations) regarding why there are ecological equivalents between many metatherians and eutherians? Discuss your hypothesis in terms of the processes that could lead to the current ecologies and distributions of metatherians and eutherians.

by the needs of each specie

Explanation:

Biologist think that the metatherians are close related with marsupials, not just for the adaptive conditions, but also because their teeth.

The eutherians are close related with the placentarian animals, the main reason of the differences is the disposition of teeth.

The hypothesis will be related to the teeth, depending the shape and the position in the mouth, make that the animals prefer to eat different food, and with the passing of time they evolve in one or other group.