Mammals have warm blood and don't normally lay eggs. Some mammals are: Humans, whales, bats, dogs, horses and cats plus more. The groups mammals fall into are marsupials(marsupials are mammals whose young are born very immature. Most female marsupials have pouches.), monotremes (monotremes are primitive, egg-laying mammals. Spiny anteaters and the duck-billed platypus are monotremes.) and placental( placental mammals are advanced mammals whose unborn young are nourished through a placenta.