I decided to create another question as this addresses another aspect of the topic I discussed in my related questions.
I know that in general, "could" is not used to describe a specific possibility in the past - I should not say "I could buy the car yesterday" when I mean that I had a chance/opportunity to buy. For that, "could have bought" should be used.
He dropped the heavy Tenontosaurus and faked an attack at the male, they both fell for it and the Aerosteon ran past them. Now he could run away if he wanted to.
In this case, I believe the could does express a single possibility/opportunity in the past, and the usage is correct. However, I do not know what usage is this, it just refer to the past, so according to one comment it is a hypothetical scenario in the present/future?
I tried to reproduce the pattern but it does not feel right:
I went to the dealership and test drove the car. I could buy it but I decided not to.
Could this be changed so that it works with simple "could" as the dinosaur example above?