Australia has maintained the uniqueness of species evolution and formed its own unique biological evolution system, which has a far-reaching impact on the evolution of animals and plants living in it. Therefore, Australia's terrestrial fauna is unmatched by other continents in the world, and there are many kinds of rare and exotic animals unique here, which are also very distinctive; This continent lacks placental mammals that are dominant in other continents. So far, there are no fierce large-scale wild animals, even snakes, and the most fierce animals are jackals. Therefore, the animals here are relatively docile, simple and honest, with obvious primitiveness, forming a harmonious biological environment.
Because there are no large fierce animals in Australia, animals like kangaroos can avoid their natural enemies by jumping twice, so they don't have to practice the 1-meter sprint and 1,-meter endurance to survive like antelope and cunning rabbits. Mammals in other continents have to learn to run soon after they are born, while many mammals in Australia have to sleep in their mothers' breast bags for several months before they can walk on the ground.
The leisurely and idyllic living conditions have caused these animals in Australia to only evolve into primitive and low-level mammals. There is even the only egg-laying mammal in the world, such as platypus.
There are 23 species of mammals, 8 species of birds, 3 species of lizards, 14 species of snakes and two types of crocodiles in Australia. Kangaroo, koala, platypus and emu are the most famous animals in Judah. Australia is the only place in the world where the oldest primitive mammal, the monotremes, is preserved. Marsupials, which are second only to monotremes in primitiveness, are the dominant animals in Australia, with more than 12 species. Endemic species are: lungfish in fish, Emodidae in birds, Cynodontidae, Cremastodontidae in reptiles, etc.
Due to the lack of fierce and fast-moving large carnivores such as wolves, tigers, leopards and lions in Australia, animals such as monotremes and marsupials can survive and reproduce in this "Xanadu". In addition, Australia was not invaded by Quaternary glaciers like Eurasia, which also made the animals here evolve slowly. The pattern on the national emblem of Australia reflects the unique animal condition here: a kangaroo on the left and an emu on the right.
Among the monotremes, there is also an anteater with thorns all over its body, whose scientific name is the echidna. Its shape is quite like a hedgehog, with short and sharp spines, small head, long tip of mouth, no teeth, and a long crawling tongue, which mainly licks insects and ants. It also lays eggs like a bird, and the hatched young mole suckles in the skin. The echidna lies in the daytime and comes out at night. When it meets natural enemies, it will quickly curl up like a hedgehog to protect itself. The echidna and platypus are the only mammals that lay eggs in the world. For this reason, these two animals and kookaburra were chosen as the mascots for the Sydney Olympic Games.