The best way to knock out a dino is to use a shocking tranq arrow with a long neck rifle. The best creature to knock out a dino is the patchy, but don't use the dinos to knock out creatures. It's not useful. But what you should do is get a bear trap or a large bear trap to trap them or a bola or chain bola best way is bear trap or go up on a rock were they cant hit you and start shooting it with tranqs.
For extra facts, shooting a tranq in a trikes head or a patchys head will do less torpor damage, but with other dinos it gives them more torpor damage. A tranq arrow with a cross bow to a parasaurs head knocks it out instantly if its bellow level 20.