This is actually about breeding and raising. When you breed them they don’t fly up they just walk so you can just put pillars around them. What I really wanted to post this comment for I how INSANELY long they take to breed, we hatched them and after 2 hours and 15 minutes and they are only 3.7% done
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.