Back Monotremata Afrikaans Kloakentiere ALS Monotremata AN وحيدات المسلك Arabic كظاميات ARZ Monotremata AST Akangoldunol (Monotremata) AVK Birdəliklilər Azerbaijani Аднапраходныя Byelorussian Аднапраходныя BE-X-OLD
| Monotremes Temporal range: Lower Cretaceous – Recent
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| Short-beaked echidna | |
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| Order: | Monotremata C.L. Bonaparte, 1837
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†Kollikodontidae | |
Monotremes are a group of mammals that form the order Monotremata. Monotremes are the only mammals that lay eggs, but they also feed their babies with milk.
The word 'monotreme' refers to their common rear opening, the cloaca. In amphibia, reptiles, birds and probably all early tetrapods, there is a common opening for urine, reproduction and faeces.