In this article we will discuss about the distinctive characters of platypus with the help of suitable diagrams. Habits and Habitat: The platypus is highly modified for aquatic life and spiny ant-eaters are terrestrial. Both are burrowing in habit, both burrow and make nests for rearing their youngs. Both are insectivorous, nocturnal, warm-blooded, quadrupedal and oviparous. External Features: Body of [...]
Marsupials are mammals basically similar to the Eutheria, but their youngs are born in a rudimentary condition and are generally sheltered during their later development within an integumentary pouch, the marsupium. However, pouch is lacking in the Australian Numbat (marsupial ant- eater, Myrmecobius fasciatus) in which the youngs are dragged along, clinging to the nipples. Marsupium is also lacking in [...]
The subclass Theria constitutes the "modern" mammals. This group includes three infraclasses, viz., the probably ancestral Jurassic Pantotheria (= Trituberculata), marsupial Metatheria and placental Eutheria, the most highly organised and advanced mammals. Metatheria and Eutheria are presumed to have arisen from some untraced branch of Jurassic pantotheres and both diverged along their separate lines of evolution during early Cretaceous period. [...]