They are not very difficult to tame, just bola, shot it with tranks, trank arrows, or just hit it in the face with a wooden club until it gets knocked out. Then just feed it berries, and wait until it tames.
Congrats, now you have a creature that has infinite stamina, collects tons of berries, and it is a seed-making machine.
Gets rare flowers to the point that they don't feel rare. Infinite stamina in run mode along with a good base weight, along with the ability to use tools on its back makes for an all purpose tame that makes the trike feel completely obsolete, cannot recommend enough.
This guy is absolutely SPECTACULAR for an early game gatherer and attacker steps on how to tame: 1 encounter an iguanodon and make sure you have at least 2 bolas ready 2 after you knock it out with a club or fists etc, feed it a bunch of berries and after about 5-10 minutes you have an iguanodon! Hope this was helpful :D