Unlike eutherians, both monotremes and marsupials
a. Lack nipples
b. Have some embryonic development outside the uterus
c. Lay eggs
d. Are found in Australia and Africa

Verified step by step guidance

1. Understand the key differences between eutherians, monotremes, and marsupials. Eutherians are placental mammals, while monotremes and marsupials have different reproductive strategies.
2. Monotremes are unique among mammals because they lay eggs. This is a key characteristic that distinguishes them from eutherians and marsupials.
3. Marsupials give birth to live young, but these young are typically underdeveloped and continue their development in a pouch outside the uterus. This is a significant difference from eutherians, which have more developed young at birth.
4. Both monotremes and marsupials are known to have some embryonic development outside the uterus, unlike eutherians where development is entirely within the uterus.
5. Consider the geographical distribution of these animals. Monotremes are primarily found in Australia and New Guinea, while marsupials are predominantly found in Australia, with some species in the Americas.

Key Concepts

Eutherians

Eutherians, also known as placental mammals, are characterized by having a complex placenta that allows for extensive embryonic development within the uterus. This group includes most mammals, such as humans, dogs, and whales, and they typically have nipples for feeding their young.

Monotremes

Monotremes are a unique group of egg-laying mammals, including species like the platypus and echidna. Unlike other mammals, monotremes lack nipples and instead secrete milk through specialized mammary glands. They are primarily found in Australia and New Guinea.

Marsupials

Marsupials are mammals that give birth to relatively undeveloped young, which then continue their development in a pouch. This group includes kangaroos, koalas, and opossums. Marsupials are predominantly found in Australia, with some species in the Americas, and they have nipples to nourish their young.