Looking back over the fossil record, it becomes apparent that when a new form of life emerges it develops into many variations whilst conditions are favourable. Meanwhile, in the background, the basic, prototype, organism keeps chugging along. Then there is a disaster of some sort and the variations die out. Sometimes it is bad enough that the basic types go as well, there are no ammonites and nautilus swimming in our seas now, but you can see in the fossil record that the basic forms were not wiped out in the first disaster, they carried on, giving birth to a new bunch of variants as conditions improved.
It applies with many major groups, the basic forms remain, frogs, sharks and crocodiles are very old basic types, though other variants have come and gone. Compared to amphibians, fish, and reptiles the mammals are the new kid on the evolutionary block, and the basic type was some sort of tree shrew, not that different from a rat or mouse functionally, and if any mammals survive the next disaster, following that principle tells us it will be something along those lines, the basic type, and the specialist variations, like elephants, giant pandas, and us, are due for extinction
Of course it could be argued that the development of intelligence and language is the equivalent of a new division in the animal kingdom, geneticists tell us we just about made it through last time. I am not sure how useful intelligence is when it comes to it. Time to try outwitting a rat.