Best way to kill alpha raptor is trike. Its Easy. You have to click attack button (when you are riding the trike) when A.raptor is few meter away and it will pushed back. repeat it again and again. don’t let it to come near the trike or it will able to attack. only problem is trike easily run out of stamina. I have done this 2 times with x2 xp mutiplier and once killed your trike will up by 6+ levels