Is the platypus, an underevolved Australian mammal, viviparous or oviparous?

Platypus is one of the most primitive mammals, it is not fully evolved mammals, there are very few species, platypus is the only animal in the same genus, but also one of the lowest mammals. The platypus has a mouth and feet like a duck, and a body and tail like a beaver. It appeared 25 million years ago and still lives in Australia. Due to the small number and small distribution of platypus, no subspecies have been found. So is the platypus viviparous or egg-laying? According to Australian animal data, although the platypus is a mammal, it lays eggs. The platypus lays eggs in the nest, 2-3 eggs at a time. Eggs are smaller than sparrow eggs and stick to each other. After two weeks of hatching, the platypus is born. During the incubation period, the hole is blocked, and the hatched cubs are not fully developed. Platypus have neither pouches nor nipples. Bundles of mammary glands open directly into the breast area of the abdomen. The cubs feed the milk with a retractable tongue, and the lactation period is about five months. Rely on breastfeeding for 4 months before you can go out to find food on your own. if you are more than 2 years old, you will be considered an adult, and your life expectancy is generally 10-15 years.

Because platypus can lay eggs like reptiles or birds, and after hatching, they can feed their young like mammals, which runs counter to scientists' existing distinction between mammals and non-mammals. After much controversy and research, scientists have finally come to the conclusion that this strange creature belongs to the "monotremes" family, or "egg-laying mammals". This animal represents a part of the evolution from reptile to mammal.

The platypus is covered in soft brown bushy short hair. Its skull is smaller than that of the echidna, and its brain is hemispherical and smooth. The limbs are very short, with hooked claws on the five toes and thin flippers between the toes, resembling duck feet. When walking or digging, the webbed folds in the opposite direction on the palm. It is covered with soft fur, like a good waterproof coat, the mouth is extremely wide and flat, mounted on the head like a mask, shaped like a duck's beak, soft, leather-like, and covered with nerves that can be like a radar scanner to receive radio waves from other animals. The platypus relies on this weapon to find food and direction in the water. There are wide horny gums in the mouth, but no teeth, the tail is large and flat, accounting for 1 / 4 of the body length, which acts as a rudder when swimming in the water.

The adult platypus is 40-50 cm long and weighs between 700-1600 grams for females and 1000-2400 grams for males.

The platypus has a low body temperature and can fluctuate rapidly.