Hierarchy classification:

1. top of the aat hierarchies
2. Agents Facet
3. Living Organisms (hierarchy name)
4. living organisms (entities)
5. Eukaryota (domain)
6. Animalia (kingdom)
7. Chordata (phylum)
8. Vertebrata (subphylum)
9. Mammalia (class)

Anotations

Scope note:

Subclass of primitive mammal including monotremes and their extinct relatives, characterized by being egg-laying, having hair, mammary glands without nipples, a pectoral girdle, and separate oviducts that open into a cloacal chamber that is shared with excretory ducts. Most of the animals in this group are extinct, known from fossils of the Cretaceous and Cenozoic periods. They are represented today by the monotremes, platypus and several species of echidna.