They take about 8 bites. If not 8 then 7 or 9 but most times 8. You can hang back behind them and count their chomps. I tried going under. People said they don’t care but the one I tamed kept making me going in circles to avoid getting pushed. I decided to hang back instead by a fair distance like at the tip of the tail
When taming to make it easier stand against a cliff or a good sized rock. I tamed one for my brother and it was a piece of cake with that technique. Also if you find that the place you find the diplodocus isn’t safe just get near it and lead it away. They won’t hurt you they just like to swat you around like they are playing a game of soccer.