Why are there only polar bears and no Antarctic bears? Are there no penguins in the Arctic? Seek an answer

Bears did not evolve before the Antarctic continent drifted away from other continents. Penguins enter the Antarctic continent through Cape Horn, Argentina, and then gradually adapt to the Antarctic climate. It should be said that there are no polar bears in Antarctica and no penguins in the Arctic, which just shows the contingency and non-repeatability of evolution. Hello question 1: Antarctica is an isolated road, which is covered by glaciers, while the North Pole is an extension of Eurasia, and their geographical environments are different. Polar bear is an advanced carnivore. There are many middle and lower animals supporting it at the top of the food chain, but there are no such middle and lower animals in Antarctica. Polar bears can't survive even in the South Pole, so there are no bears in the South Pole. Question 2: In fact, a penguin once lived in the Arctic a long time ago, and now it is extinct. Known as the "Arctic Giant Penguin", this penguin is 60 cm tall, with a brown head and black feathers on its back, much like a foreign gentleman in an evening dress. They live in what is now Scandinavia, Canada and northern Russia, as well as all the Arctic and subarctic islands. At the peak, the number reached several million. About 1000 years ago, the vikings discovered giant penguins. From then on, the bad luck of the big penguin came. Especially after the16th century, the arctic exploration fever rose, and giant penguins became the hunting targets of explorers, navigators and aborigines. Long-term hunting and indiscriminate killing led to the complete extinction of Arctic penguins. The ancestors of penguins living in the Antarctic today developed in areas south of the equator. Scientists speculate that the reason why they don't continue to push north to the northern hemisphere may be that penguins can't stand warm tropical waters. The northernmost limit of their distribution range is very consistent with the connection line of the area with an annual average temperature of 20℃. The equatorial warm current and high temperature form a natural barrier, which prevents penguins from crossing the equator to the north. They must stay in the sea area where ice and snow from Antarctica melt water or cold water flowing in the deep sea passes. The results of paleontological research show that penguins appeared in Tertiary as early as 50 million years ago, and it was found that penguins once lived in the Arctic, because an extinct bird skeleton was found in the Arctic, which was called "Big Penguin". This "big penguin" is about 60 cm tall, with a brown head, black feathers on the back and a white abdomen. They are as clumsy as other penguins when walking on land, but they are also good at swimming in the sea. "Big Penguins" are mainly distributed in Europe, Scandinavia, Asia and North America, and some islands in the Arctic Ocean, with a number of one million. However, three or four hundred years ago, Europe set off an upsurge of exploring the Arctic. With the arrival of explorers and immigrants, the "big penguin" has become the object of contention, and its number has dropped sharply. When the last "big penguin" was killed, there were no penguins in the northern hemisphere. This is why there are no penguins in the Arctic. Why there are no bears in Antarctica? Before the ancestors of bears appeared, Antarctica was a continent surrounded by oceans and was not connected with other continents. The division of the ocean makes it impossible for bears on land to migrate there, so it is impossible to find polar bears in Antarctica. On this continent with an area of140,000 square kilometers, there are no animals of continental flora, and all animals are classified as marine fauna]