Most of these species are placental mammals or eutherian mammals. Their name comes from the placenta a structure that transfers nutrients from the mother to the embryo and removes waste products of the embryos metabolism. Rapid reproductive cycling an adaptation to uncertain conditions. Are found in Australia Mammals have many unique distinguishing characteristics. Many types in the same mouth Ears are distinctive and elaborate.
Kidneys are good at concentrating urine and conserving water.
Big Brains Reproductive modes. Most are viviparous. Offspring can develop rapidly with rich food under care of parent. Possess hair which is composed of keratin but is not believed to have evolved from reptilian scales. They have an efficient respiratory system which utilizes a diaphragm for ventilation.