Another good way to tame solo a Quetzal on an online server is the way with the Wyvern, when you have access to one. I did it yesterday with a 176 Tek Quetzal: make the Wyvern on "follow", fly to the Quetzal (I fly under or beside it), press the "air brake" button to stand still, dismount of the Wyvern and important: don't move! Then you stand on the back of your Wyvern while in the air and then you can shoot the Quetzal. Then look down on your Wyvern, mount up again and repeat it, until it's done. When it falls down, you also have a great defending Dino with the Wyvern against other dangerous things, like Carno, Rex and so on.
If you drop a quetzal due to knockout, and it lands next to a giga...just know, the quetzal belong to the giga. Now you get to watch your would be quetzal get eaten by a giga. Now you can go home and cry.
If you manage to knock a quetzal out, try starve taming. If you never tried starve taming it’s just leaving a Dino’s hunger go to half way or lower and then you start feeding. I’ve done this many times and it’s very useful taming trick.