Easiest way to tame: make a dino pen, pick one up with an argy, put it in the dino pen then follow along with a basic taming process (knock it out, feed it). Make sure you have lots of narcotics on you!
Best thing about them: they can climb up really steep hills and they can potentially do lots of damage and can be fast.
Where to find: most commonly found on trees (they will be hanging upside down, high up on large trees) in the redwood forest areas (mainly on The Center) or I find lots of them in the Ragnorok desert.
The redwoods are now basically a no fly zone, I lost a quetz, and a pter to these bastards. They jump out of the tree, rip you off your mount, and then pin you and your mastercraft armor to the ground and murder you.