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Kangaroo Island Travel Guide
Kangaroo Island Wildlife - Monotremes
About Monotremes
- Living monotremes comprise the platypus and two species of echidna.
- They are unique in that they are egg laying mammals, rather than giving birth to live young.
- The male platypus is also unique among mammals, being venomous (toxin is injected through a hollow spur on the ankle).
- It is assumed that monotremes branched off early in mammalian evolution, and retained many reptilian features (ie. laying eggs).
- The order comprises two families: Ornithorhynchidae (Platypus), Tachyglossidae (Echidna).
More like a lizard or a mammal?
It has been suggested that monotremes evolved earlier than other types of mammals.
Reasons for this include:
- Egg laying
- Lack of nipple (instead they ooze milk from mammary glands)
- Cooler body temperature than other mammals
- Legs which extend out, and then vertically below them
For these reasons, it appears that features of monotremes are more like that of lizards, rather than mammals. However, they are mammals!