A caiman is a fairly small crocodile living in South America. The jaguar is one of the big cats and a roaring cat. The interesting fact about the jaguar is that it has the strongest bite of any of the wild cat species and substantially harder than the tiger. The tiger's bite is also harder than the lion's.
Judging by the images it seems that the jaguar used its impressive bite force to kill the caiman by biting the back of its neck somewhere near the nape of the neck in the same way that a domestic cat kills a mouse by biting the nape of the neck which splits open the vertebrae.
Cats do this very accurately by feeling where the vertebrae are and where they meet. I think this is the interesting aspect of this story; the way the jaguar kills this South American crocodile
It is an example of a superior predator using its inherent attributes to kill prey efficiently.