Question

Which of the following is Prototherian?
A) Platypus
B) Macropus
C) Opossum
D) Bradypus

Answer 1

Mammalia Class is the largest one in the Animal kingdom. Based on their reproduction abilities, they are classified further into 3 subclasses: Eutheria, Metatheria, and Prototheria.

Complete answer:
Let us analyse the options to find the correct answer.

Option A: Prototheria - also called Monotremes, consists of egg-laying mammals. It has one order having 6 species. Order: Monotremata. For example - Omithorhynchus, Tachyglossus (Echidna).
Most of the animals in this group are extinct.
Prototherians are considered to be the most primitive mammals, only restricted in Australia and its neighbouring islands.
Example: Duck Billed platypus, Echidna.
Therefore, this is the correct option.
Option B: Macropus - Macropus is a marsupial genus that belongs to the family Macropodidae.
The term itself is derived from the Ancient Greek makros "long" and pous "foot".Therefore, this is the incorrect option.
Option C: Opossum- Opossum, also called as - possum, were formerly grouped together in the order Marsupialia. The word opossum is derived from the Algonquian word “apasum” which means - “white animal”.Therefore, this is the incorrect option.
Option D: Bradypus - The three-toed sloths are arboreal neotropical mammals (also called the "three-fingered" sloths). They are the only members of the genus Bradypus, and of the family Bradypodidae. Therefore, this is the incorrect option.

Thus, the correct option is (A) Platypus.

Note: Prototherians had split from their Eutherian and Metatherian ancestors, a long time before these became placental and thus became more adapted to the harsher and more diverse environments.