Mammal Classification and Diversity

Study Notes

Class Mammalia divided into three subgroups based on reproductive methods: monotremes, marsupials, and placental mammals.

Egg-laying mammals exemplified by the duck-billed platypus and echidna.
Found exclusively in Australia, Tasmania, and New Guinea.
Unique traits include reptilian-like bone structure in the shoulder area and lower body temperature than most mammals.
Chromosomes exhibit a mix of sizes: normal mammal size and smaller reptile size.

Characterized by short gestation periods; offspring enter a pouch after birth.
Offspring develop and are nourished by milk from mammary glands within the pouch.
Predominantly found in Australia and surrounding islands; the opossum is the sole native marsupial in North America.

Feature a placenta providing food, oxygen, and waste removal for developing young.
Births produce young that do not require pouch development.
Represented by 18 different orders, showcasing significant diversity in adaptations.

Order Insectivora: Includes shrews, hedgehogs, moles; small, underground insectivores with pointed snouts.
Order Chiroptera: Bats, active at night, utilizing sonar for navigation, adapted for flight, consuming fruits and insects.
Order Primates: Comprising monkeys, apes, and humans; exhibit binocular vision, larger brains, tree-dwelling habits, and opposable thumbs.
Order Xenarthra: Includes anteaters, sloths, armadillos; notable for toothless or peg-like teeth adapting them for insectivory.
Order Rodentia: Features beavers, rats, squirrels, etc.; possess sharp incisor teeth suited for herbivorous diets.
Order Lagomorpha: Rabbits, pikas, and hares; characterized by longer back legs compared to front legs for jumping, with continuously growing incisors.
Order Carnivora: Comprising dogs, cats, wolves, bears, and seals; specialized teeth for tearing flesh, making them proficient meat-eaters.