These are fairly easy to knock out.

So I did. I tamed one on the beach by the river near the green obelisk. I named him scary boi. I was level 45 so I couldnt get the saddle yet so he just sat by my base until I could. And when I got that saddle I was amazed by the power of this creature! I regularly crossed the map with scary boi and I never had to worry about other dinos (except for gigas and titans obviously)

And taming them is easy. Shoot them in the face with tranqs from a cliff and shove some fish meat/kibble up their butt (make sure to keep an eye on their torpor!)

Now go get one