A pain in the azz
 

And then in the head.....

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shows the value of hunting in social groups

looks like it might have gone on to end badly for the cape buffalo.

I wonder if the buffalo escaped...could he survive after having the lions fangs embedded in his backside? Might have been better for him (quicker death) if the lion had hung on.

Is the ass biting a way to cripple the buffalo ?

^^^ It's prob the only vulnerable spot without getting gored. Just guessing.

i think i read that the lion is trying to sever the spine to shut off the rear legs (?)

^^^
between trying to do that and dodging the buffalos hooves....that lion is risking his life also.