Shouldn’t the biggest and baddest left fossils. Shouldn’t we be asking where they are just like Darwin did?
Pray for America
The biggest and baddest don't need fossils, their descendants are still around.
The extinct are known by their fossils.
Just like there are no desert penguins nor arctic scorpions, if there were, they didn't last long. If at some point radical climate changes happened, only those creatures who were smart enough to adapt or migrate, or who were inherently able to survive environmental changes, survived.
That doesn't mean they mutated, only that resilient families of a given species lived through some adverse condition (weather, predators, volcanos, meteors, drought, an ice age, etc) the weaker/dumber/slower members perished.
This doesn't have anything to do with evolving from monkeys.