Monotreme

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Kollikodontidae (extinct)

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Ornithorhynchidae - Platypus

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Tachyglossidae - Echidnas

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Steropodontidae (extinct)

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Monotremes (< monos, single + trema, hole; refers to the cloaca) are mammals that are best known for laying eggs, instead of giving birth to live young like marsupials (Metatheria) and placental mammals (Eutheria). The subclass comprises a single order, Monotremata (though sometimes the subclass Prototheria is used).

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Platypus: This article is about the mammal. For the genus see ambrosia beetle. For the progressive rock band see Platypus (band)...

Tachyglossidae: redirect Echidna...

Echidna: :For other uses, see Echidna (disambiguation)....