These guys are awesome! I have yet to make a saddle even though it was a while ago I unlocked the saddle. For taking, I used a cross bow and tranq arrows. Got it to chase me while I was in my Argy and perched on a rock, shot it quite a few times then fed it raw meat. You can easily tame it on land. Just lure it away from the swamp (look out for all dangerous creatures including the leaping croc, kaprosuchus) and it walks slowly on land. Shoot it and down it!