Panthera leo atrox… An actual subspecies of lion found in the Americas but is now extinct.
Not Puma concolor, which isn’t even a big cat.
Big cats are in the clade that includes the genus Panthera, the two species of clouded leopard (which are smaller than cougars), and the snow leopard, which is actually very similar to the most primitive of the true big cats.
Cougars are most closely related to the jaguarundis, which are not jaguars, and both are closely related to cheetah.
I will NEVER use the term “mountain lion’ to describe Puma concolor. I call them cougars.