Mammals are taxonomically divided into three groups: placental animals, marsupial animals and monotreme animals. The lattest belong to the smallest group – it contains only three species: the duck billed platypus and echidna, and another species of echidna found in New Guinea. Here are some photos and facts about these interesting animals.
More Primitive than Marsupials and Placentals They have never been as numerous as other groups of Australian animals such as marsupials and placentals. Fossil evidence suggests that they were around before the final break-up of Gondwana. They have smaller brains than placentals and marsupials, but like marsupials, their lower metabolic rate and body temperature make them more energy efficient.
Both Mammalian and Reptilian Characteristics Monotremes are the most unique group of Australian animals, and it took a little bit of confusion before they were classified as mammals. They do have fur and they produce milk – two most important features of mammals. But they lay eggs like reptiles, and they have no nipples - the baby sucks the milk off the fur instead. And like reptiles, they have a single hole for eggs, urine and faeces. This mixture of mammalian and reptilian characteristics suggests that they descended from a very early branch of mammals.
NOTE: This website is written in British English, which is the English we use in Australia. You will find words like "traveller", "harbour" and "realise", and they are all correct in the language used in Australia.
