Here's why:
* Placental mammals are mammals that give birth to live young after a period of gestation in the mother's womb. The offspring receive nourishment through a placenta, which is a temporary organ that connects the developing fetus to the mother's circulatory system.
* Red foxes fit this definition perfectly. They give birth to live pups after a gestation period of about 50-60 days. The pups are nourished and develop inside their mother's womb.
Therefore, red foxes are a prime example of placental mammals.