Australian Monotreme Animals

There are two monotreme animals in Australia.
Mammals are taxonomically divided into three groups: placentals, marsupials and monotremes.
The lattest belong to the smallest group – it contains only three species: the duck billed platypus and short beaked echidna found in Australia, and long beaked echidna found in New Guinea.
 

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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 Gondwanaland. They have smaller brains than placentals and marsupials, but like marsupials, their lower metabolic rate and body temperature make them more energy efficient than placentals.


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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.