Seems like after the tlc patch they are harder to down, im on unofficial with damage numbers and it looks like theres no headshot multiplier and it took about 60 hits with a crossbow to down a 150 with fairly regular hits
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.