Are these things some kind of sick joke? I've only been playing Ark for a couple months, and let's just say my first encounter with one didn't go well.
So there I was minding my own business, on a routine flight between bases in the middle of the night when out of the corner of my eye I see the faint outline of some giant skyscraper looking thing off to my right, and thought to myself "nothing that tall could be dangerous. Let's take a little detour and check it out". Well... seeing as how it was the dead of night, by the time I got close enough to realize it was a dino, I was already in range, and before I even had a chance to react the thing like headbutted me, my blood wyvern got stuck in its neck, I went flying, and as I'm plunging to my death I get the message that my dear wyvern friend Vlad (he'd been with me for a month) had perished, presumably still stuck in that stupid thing's neck. Ruined my whole day.
Now, I don't know if these things are normally aggressive, or if I was just unfortunate enough to approach while it was locked in a battle with other wild dinos, but after today my advice is not to go anywhere near em because even if it's the latter and they're normally docile, I think it's safe to say that they're pretty darn glitchy.
Easily killable with a wyvern. Lightning and poison easiest down to longer range in attack. Just hover above and light it up :) killed my first today and it didn't touch me once. Just remember to watch stamina ;)