Prototheriaegg-laying mammals.

What are the 3 mammals that lay eggs?

These three groups are monotremes, marsupials, and the largest group, placental mammals. Monotremes are mammals that lay eggs. The only monotremes that are alive today are the spiny anteater, or echidna, and the platypus. They live in Australia, Tasmania, and New Guinea.

What are the characteristics of Prototheria?

Subclass Prototheria Primitive; egg-laying; hair; mammary glands without nipples; pectoral girdle; separate oviducts that open into cloacal chamber that is shared with excretory ducts; oviparous.