1. Increased Protection and Nourishment: The placenta provides a much more direct and efficient connection between the mother and developing fetus. This allows for a greater transfer of nutrients and oxygen, as well as the removal of waste products. This results in a more developed and larger offspring at birth.
2. Longer Gestation Period: Placental mammals have a significantly longer gestation period than marsupials. This allows for more time for the offspring to develop inside the mother's body, resulting in a more mature and independent newborn. This gives placental mammals an advantage in terms of survival rates and the ability to adapt to a wider range of environments.
It's important to note that both placental and marsupial mammals have evolved successful strategies for raising offspring. Each pattern has its own strengths and weaknesses, and both groups have thrived in their respective ecological niches.