Make a taming pen->Take your argentavis->head on to the dead Island(carno island)->find a good level with spy glass->grab that sabertooth with your argentavis->bring saber back to your taming pen and drop'em!.->tranq 'em->

Feed 'em.

(If argentavis is on low of health,drop sabertooth on a safe place and kill some parasaur to regain health and stam)

Tip for developer if any..

Sabertooth needs a critical attack (35-45%+damage)after killing,for a period of time..[atleast they are saber toothed]

More Sabertooth Taming & KO Tips