I figured out the easiest way to tame them! You'll need a Deinosuchus since they barely get knocked back from the Acro due to their low stance.

Ride the Deino and bite the Acro until the Acro does it's feeding roar, then dismount quickly and feed the biotoxin. Get back on the Deino and repeat. You'll be tanking the Acro's attacks so watch your Deino's health. When the Acro does its stomp or fake roar, stay on the Deino and you'll only get knocked back a tiny amount. You can easily knock a max one out in a couple of minutes this way.

You can’t tranq this Dino you must shoot it until it roars then run up to its lower jaw and feed it biotoxin. My buddy try to tranq it and used 88 of our tranqs. Enjoy this info like we would’ve

When taming these dont try to trap them as it typically causes them to never go into shield stance. Fret not i have an easy guide, once you get it into shield stance count how many shots it takes to enrage it (normally 5 with a good pump) shoot your amount of counted shots then back up and it will roar, then run up and feed it your narcotic or more ideally biotoxin then immediately back up a good distance and as soon as it is done with its animation it SHOULD go right back into shield stance allowing you to rinse and repeat this method safely on foot. WORDS OF WARNING kill everything nearby as to not mess with the process, you know you are safe to start shooting when it stands straight then goes into its shield stance, ONLY approach it AFTER it does the correct roar since it has 2 roars, the one you are looking for and a fake/taunting roar which if approached when its doing this second roar will cause it to enrage and and start attacking everything for 30 seconds and will kill you very quickly. IF it does the fake roar simply stand back a good bit and wait for it to finish, after it does it'll do the correct roar and you then run up and feed it like normal. with this method and a little practice you can tame one without ever really getting hit whilst on foot. ALSO the second roar isnt nearly as loud as the first and looks a bit different and the acro will laugh at you (literally) after doing this fake roar if it doesnt get enraged by tricking you. Lastly these things are BEASTS, you and a tribemate can grab 2 bred acros with asc saddles and kill alpha monkey with just those 2 acros, they can also solo the hard ice cave on the island but youll want a good saddle, hope this helps and like so others may see

You don't need to target its mouth when feeding narcotics or biotoxin, any part of its body will give you the option to feed.

An easy way to tame him once you are into late-game and have a Tek chestplate.

-a good amount of Bio toxin.

-try avoiding Pump shotguns and rather go for a fabricated sniper rifle. (The rifle does damage in per bullet which makes it easier to control the situation)

-a tek chestplate.

So basically you just hover over him and tick away his health until he goes into a defensive stance. Tick away some more and he SOMETIMES does his adrenaline roar. Not to be mistaken with his health restoration roar. Once he does his roar you need to dive bomb him by disabling your chestplate and spamming the feeding button. And basically rinse and repeat!

And if somehow you screw up and do his health too low you can lead him to weak creatures, he will eat them and restore about 50% of his health which grants you a second chance!

A bit confusing, but a good way to tell a wild acros damage stat without mods:

Use your own acro. Get into shield stance, and force wild acro into shield stance. Whatever the damage done by the acros BITE in shield stance to your own acro in shield stance is the damage stat. For example, if it does 33 damage per bite, it has 33 points into melee. Nothing game breaking but I thought I’d share

If you use an ascended shotgun, watch how many times you unload in them. Also use bio toxic, narco will take way too long to tame them with.

Tested taming extensively.

1. The acro does not seem to care about the damage output you are dealing while you shoot it, it cares how many times you shoot it and with what weapon. Use primitive to reduce the chances of killing it. Shotgun is best.

2. While it is doing the fake roar it will constantly regenerate health to full for the entire duration of the animation, this is a great opportunity to lay into it and force it back into shield mode.

3. If you do not shoot it during the false roar, it will become impervious to damage for about 5-6 seconds, do not waste your ammo during this time.

Be careful because if one is to low of a level you might accidentally kill it when trying to tame it

Having tamed quite a few of these on center and on the new gen one map I've learned a few things. First come prepared, make sure you have enough biotoxin or narcotics and ammo. Second you don't have to use a pump shotgun, double barrel feels much better because it's higher damage and doesn't waste as many shots. And last taming on foot is a lot easier than you think, just kite it shoot it and feed. Good luck