Very easy to tame if you know what your doing. First tame an Ichthyosaur. Then grab a crossbow and some tranq arrows and find one and knock it out. It is not be able to attack if you are on the Ichthy. As you are taming it, be sure to remain on the Ichthy unless feeding narcs, so other creature don’t hurt you. Vote up if this helped
They may seem calm, and won't be dangerous most of the time, but don't be fooled: They boast descent damage and godlike resistance, think of them as Rock Elementals of the sea, exchanging HP for numbers.
Just like elementals, they have a small aggro range, very slow movement speed and not the highest of the DPS. But if you get cornered, be ready to suffer a slow death by their stone-crushing jaws.