Tag: classifications of chordata

• Prosimians include The lemurs, lorises and tarsiers and Simians include The monkeys, apes and man.
  
• Prosimians are primitive primates. They retain claws on some digits, having nails on others. The hindlimbs are longer than forelimbs. The tail may be present or lacking.
  
• Simians have nails on the digits. Forelimbs are longer than the hindlimbs. The tail may or may not occur.
  

The birds can lift their body and fly in the air due to the capability that the wings have the structure to push the air in the backward direction. This allows the bird to fly upward and forward by applying force and moving the air back.

Platypus and Echidna are warm-blooded animals. They belong to Mammalia because they have hair on their body and produce milk from mammary glands to feed their young ones. However, they lay eggs without giving birth to young ones. Laying eggs is characteristics of class Reptilia. Hence they form a link between reptiles and mammals. 

(A)Reptilia is a class of crawling animals where the members lay eggs.

Artiodactyla is an order possessing cloven-hooved mammals. Generally, they are ruminants but some non-ruminant members are Pigs and Hippopotamus.

Monotremes or Prototheria are mammals that do not give birth to live young ones. Instead, they lay eggs and nurse them after they have hatched. They have mammary glands but no teats. They simply pour milk onto their skin and it gets collected in a pouch where the babies can drink it from.

So the correct answer is 'Prototheria'.

Animals belonging to the subclass Prototheria lay eggs like non-mammals. But they feed their newborns with the secretions of their mammary glands. They are also called Monotremes as they have a single opening for both excretion and reproduction. There are only three surviving species of monotremes, spiny anteaters are one of them.

(A)Monotremes are the egg-laying mammals.