Chp 33 – Rise of the Mammals Definition of a Mammal: 1.Homoeothermic – meaning that mammals produce their own body heat 2.Mammary tissue - for the production of Milk 3.Hair Follicles - for the production of Hair 4.Generally, internal fertilization and harboring of young, however, this is only a generality because not all young are cooked to term internally.
Monotremes – an Order of Class Mammalia Monotremes eg. The Platypus, which has a BILL, lays EGGS, but still has mammary glands and produces MILK for young. This suggests a relationship between REPTILES, BIRDS and mammals. Imagine that?
Marsupials – eg. The Kangaroo, which is a non-placental mammal. Here, the development of the young is very complex, and a baby kangaroo is born veryuncooked, and must crawl into the mothers pouch and latch onto a nipple to receive milk to continue development. You might say, baby Kangaroos or Joeys get a womb with a view