Knocking one out is easy. Since they computer right at you and arnt the fasted creature on the ark all you have to do is use a bow and walk backwards shooting it in the face with tranq arrows. Once knocked out it can only be tamed with prime meat Fish/Regular. But cautious prime meat spoils quickly so do your best to starve tame and stockpile prime during the tame to take advantage of a longer spoil timer.
I found a level 1(by chance), and it took me 14 seconds to tame. I found thirteen more over the month, and by February(found my first one at January), I had an army. I took down a whole Allosuarus in seconds with the army, but we had a PVP war, and..........eleven fell to my enemy's Trexes and Baryonyx. Only one remains now, and I keep him in my ark Basement. His names JasonBourne