Lure an argie into an enclosure where it cant escape and you can ko it or tranq the argie till the argie starts running away then pull up with a moth and fart on it and then its basically stuck for 30 seconds, easy ko
An argentavis can't fit through a ceiling with one tile missing, but a pteranadon or lymantria can. Build a trap with one corner ceiling missing, aggro the argentavis, fly in one side and out the missing ceiling tile, and land. Dismount, run around, and close the entry door. Tame safely at your leisure.
Getting a massive TLC update in March 2018. The saddle will act as a mobile smithy, Argentavis will be able to carry with Talons as well as with its beak, reduced carry weight on obsidian and a few other unannounced resources (similar to the mammoth and wood), and will also gain a Rapid HP Regen upon eating (likely from devouring corpses and not specifically food from inventory). Like so people can see!
Use left trigger to pick up animals. Right trigger to attack, witch can also be used on a picked up enemy's. pull left stick back to decelerate and forward on the stick to accelerate. The jump button is used to land and fly.
While slower than a ptera, they're pretty useful. They can pick up more dinosaurs and can kill them while flying, allowing you to pick off raptors and sabres and other small horrors with relative safety. Keep an eye on their stamina, just like a ptera you don't want to be forced down into a death trap
If you want to tame one in a safe area, aggro it with a pteranodon (because they are faster fliers than argents) and lure them to a safer area
ex. Empty Beach area. Be sure the argent is close behind you by flying slowly and when it gets a little too close, speed fly a bit then slow down, this also saves stamina. The argent might lose interest every so often but then just turn back and aggro them again. Once you reach the area, land the pteranodon, let the argent get close and tranq it
If you ever encounter one in the wild, and you are in an early stage in the game, run the opposite direction. Also try not to agrovate it unless you are up to the KO/Fight.
Good luck if you encounter it!