Mammals of Australia introductions of placental mammals into Australian fauna were about (rats), several thousand years ago (dingo), and 200 years ago (many species); the last two were made by humans. Some claims were made about placental mammal fossils from the Eocene of Australia, called "Tingamarra". These claims are based on only one found tooth having some characteristic features of condylarth, and were discussed widely. But both the age and placental nature of these fossils were challenged by other researchers. Monotremes are mammals with a unique method of reproduction: they lay eggs instead of giving birth to live young. Two of the five
Lactation Lactation Lactation describes the secretion of milk from the mammary glands and the period of time that a mother lactates to feed her young. The process can occur with all post-pregnancy female mammals, although it predates mammals. In humans the process of feeding milk is also called "breastfeeding" or "nursing". Newborn infants often produce some milk from their own breast tissue, known colloquially as witch's milk. In most species, milk comes out of the mother's nipples; however, the monotremes, egg-laying mammals, lack nipples and release milk through ducts in the abdomen. In only one species of mammal, the Dayak fruit