Get a friend with a good riot or metal shield to tank it while you knock it out with a good long neck or shocking tranq darts...it was an easy tame for us, but if you use shocking darts, you have to transfer them over so just use a good longneck.
You don’t need to trap this to tame, it’s a solo tame. If you run up to it, it will go into turret mode then you need to walk circles around it and keep hitting with tranq until it eventually tries to walk away *in turret mode so really slow walking*
I found a bug a few days ago with a pteradacle if that is how you pronuce it. If you use the pteradacle and walk up to a velonasaur on it for some reason the velonasaur goes into turret mode and does not shoot or anything. It just stands there so just walk up to one with a pteradacle and when it stares into your pteradacle for forever just load it with trans off of the pteradacle and you got a velonasaur.
Up for people to see this is the easiest way to tame this guy.
If you tame one, I suggest using this method. First, build a 1x1 of any material except thatch ( since they can break it). on each of the walls, place a window. Whenever you need to shoot, you open a window and shoot. Close the window to reload and to be protected from the needles. I had my tribe mate do this because we made a bet that if he survived while trying to knock out the Dino, he would give me his armor. Hope this helps you tame a velonosuar!