Comparing big cats - differences/changes with time

[Pckts]

Competition in the pantanal is 2nd to none, but for the most part I agree with you.
But when you see Jaguars, you realize how similar their body is to a giant river Otter. 
Obviously they're still very different but, they still share similarities that no other big cat shares.
This has got to do with the fact that they're hunting animals that are more adept in the water than land.
I'm not saying that they'll stop running on land, I'm just comparing their features to that of a specialized aquatic predator.

In regards to large mammals, they dont occur nearly as often in north, whether due to human hunting or Jaguar densisty is up for debate but regardless, they just dont exist like that in the North. The main animals you see there are capybara and Caiman. 
They're both very adept swimmers and never stray far from the waters edge. They also usually sit with one another so they probably require the same tactics. 

Tapir are no slouch, they can be double the size of a male jaguar.
But they are predated on more often in the areas they are more abdundent.
Put it this way, if you go on safari in the northern pantanal, the odds of you seeing a tapir are 1/100. Reply