Carnivores posture as an invitation to play. An adult male lion invites a cub to play by bowing before the cub (forequarters lowered): a gesture that has no other context, and an indicator that any aggressive actions that follow are play. Wolves, coyotes, and dogs use the same posture, and may wag their tails during play fights. Dog tail-wagging with humans is an indication of happiness akin to that when playing.
Young monkeys spend most of their time playing with each other. Howler monkey and gibbon infants chirp at each other to indicate that the actions that ensue are playful in intent. Other monkeys display a play face.
Playful aggression is part of behavioral development in a carnivore: for example, stalking and attack practice. In social animals, learning social graces, especially acceptable limits of aggression, are necessary for a successful life.