When taming,use full ghillie armor and take it on a place where you think there's no possible threat.Be VERY VERY careful not to touch them while petting or the taming proccess might restart. Also they can go through doorframes
Normally you can't tame the pack leader, so just get a pteranodon or argy, pick it up and drop it in a large area (like a separate section of your base). When you take it away from the rest of the pack, it removes its 'pack leader' title, allowing you to tame the highest level hyena of that pack.
Despite it's appearance, the real life hyaenodon was nowhere near related to actual hyenas, but it actually belongs to a group of prehistoric mammals, all extinct, that are believed to be most closely related to pangolins, which aren't related to anteaters or armadillos, for your information.