Very easy to tame if you know what your doing. First tame an Ichthyosaur. Then grab a crossbow and some tranq arrows and find one and knock it out. It is not be able to attack if you are on the Ichthy. As you are taming it, be sure to remain on the Ichthy unless feeding narcs, so other creature don’t hurt you.
taming a X dunkleosteus is so much harder than taming a normal one. It takes more arrows to knock it down and you will probably kill it before you can knock it down. And yet you have to deal with those stupid eels and megalodons. Be sure set up a trap and bring your friends to deal with those eels and megalodons. Solo tame is ill advised imo. And do not ride basilisaurus when you try to lure it to the trap, for some reason dunkly is afraid of the basil and it will run away from you. A ichthy is a better choice, dunkly will chase you as well as those eels, thats why a friends is needed.
OR just use command "dotame" to save your time and your dolphine.
on 5x taming server, spot a lvl 25 x-dunkleoteus, set up a trap with 24 stone pillar and 9 stone ceiling, spent 10 minutes to lure it into the trap. then pull out my 154% crossbow, sending 100+ tranq arrows....and kill it. yet sacrificing my lvl 133 dolphin to the eels and megalodon😑
Patrol your coastlines .. you sometims get them on the beaches and make easy tames, throw 3 gates around them and stand on a wyvern and dart it ... Take plenty of darts if you that lucky.. 4exceptional kibble and the jobs done 242 dunkly with very little work .. happy hunting