[sravfeyn]

I find evolution terminology funny.

Aren't the terms 'something going extinct' and 'inability to adapt' essentially same. They are symmetrically causal to one another. It has inability to adapt, hence it went extinct; it went extinct hence we say it didn't have the ability to adapt. What new unit of knowledge do we gain by saying something like the OP's title?

In short, the 'ability to adopt' is itself measured in terms of whether 'something is extinct or not'

[pizza]

They mention that the ape was mainly restricted to forests - wouldn't a metabolically-imposed habitat restriction limit the species' exposure to ex situ adaptations?

Which is to say, we gain insight into how metabolism, specialization and extinction play together. Although, perhaps this is what you meant by correlating extinction and inability to adapt?