Temperature
The Arctic, where the Polar Bears live, is pitch black and sun-less in winter and bright with the sun showing in the summer. However, the land is covered in ice and snow and the water is freezing. But Polar Bears have adapted to live in the Arctic, they have developed a 4 1/2 inch layer of fat beneath their thick fur, which keeps cold out and traps heat in. Also, Polar Bears have small ears and tails, this is so that they can hold their body warmth better. Polar Bears have black skin, it was once believed that this is because the colour black absorbs heat from the sun, but further research discovered that Polar Bears really only need all of their ingenious methods of keeping warm in the winter, in fact, they have been known to overheat in the summer. This proves that the black skin is not to absorb heat from the sun because in the winters when Polar Bears need to be warm there is no sun to give out heat and in the summer Polar Bears want to cool down, not heat up. Therefore, the reason why their skin is black remains a mystery.
So an animal that is fully adapted to keep itself warm and sometimes overheats in the ice, is not going to be able to live under boiling conditions. The layer of fat and fur would prevent any cold air getting through and the small ears would also trap heat. Although the Polar Bear's black skin is not designed to absorb heat, under the red desert sun it would absorb a lot of heat and make the Polar Bear even hotter.
So an animal that is fully adapted to keep itself warm and sometimes overheats in the ice, is not going to be able to live under boiling conditions. The layer of fat and fur would prevent any cold air getting through and the small ears would also trap heat. Although the Polar Bear's black skin is not designed to absorb heat, under the red desert sun it would absorb a lot of heat and make the Polar Bear even hotter.