i'm researching aggressive dog behavior
i'm trying to prove that dogs don't act randomly or turn on ppl...theres something there to cause it...i need examples for support.

My dog loves going to the off-leash dog park but one of the park rules is that any dog exhibiting aggressive behavior should be removed immediately. What exactly is considered aggressive behavior?

My dog runs up to other dogs while making growly noises with no teeth bared and then trying to make the other dogs run with him and chase him. Sometimes other dogs initiate play with him and he runs with them while growling. Is this considered aggressive behavior? I just need to know where exactly to draw the line.
Bluebell: He's a 2-year-old German Shepherd mix.