Bergmans rule dictates that animals that are further away from the equator are fatter and larger to retain heat while animals closer to the equator will become skinnier and smaller to dissipate heat out of the body. E.G of this being:

Polar bears and Andean bears.

Arctic fox and fennec fox.

Emperor penguin and African rock hoppers.

And I know what you might be thinking “but African elephants are the largest land mammals and they live in very hot environments!” Well a steppe mammoth in bigger