Kingdom = animalia
Pylum = chordata
class = mammalia

Modern mammals are divided into three sub-classes:

  • Prototheria (Mammals that lay eggs, also known as monotremes or Monotremata).
  • Metatheria (marsupials, pouched mammals).
  • Eutheria (placental mammals. That's me).

    Mammals are endothermic, have hair, a four-chambered heart, an single lower jaw, suckle their young, and are heterodonts. Not all mammals bear live young. Go read that bit about the Prototheria again.

  • Mam"mal (?), n.; pl. Mammals (#). [L. mammalis belonging to the breast, fr. mamma the breast or pap: cf. F. mammal.] Zool.

    One of the Mammalia.

    Age of mammals. See under Age, n., 8.

     

    © Webster 1913.

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