| Known as |
Monotremes |
Marsupials |
| Reproduction |
These are egg-laying mammals |
These are pouched mammals with live birth (viviparity) but a short gestation period |
| Development |
Hatch from eggs outside the mother’s body |
Birth at a very early stage of development and offspring continue to develop in the mother’s pouch |
| Placenta |
Lacks a true placenta |
Simple, short-lived placenta or absent |
| Mammary Glands |
Mammary glands without nipples; milk is secreted through openings in the skin |
Mammary glands with nipples; milk is delivered through nipples to the young |
| Urogenital System |
Single urogenital opening (cloaca) |
Separate urogenital and digestive openings |
| Geographic Distribution |
Found primarily in Australia and New Guinea |
Found in various parts of the world, but predominantly in Australia and the Americas |
| Number of Species |
Limited number of species |
Diverse group with a larger number of species |
| Dentition (Teeth) |
Typically have reptilian-like teeth |
Dentition often adapted to herbivorous or omnivorous diets |
| Lifespan |
Generally longer lifespan |
Shorter lifespan |
| Developmental Stages |
Egg, hatchling and juvenile stages |
Neonate, pouch young and weaned stages |
| Examples
|
· Platypus
· Echidnas
|
· Kangaroos
· Wallabies
· Koalas
· Opossums |
