To craft one, you must kill a wild one and the one you kill there will be a Blueprint for it in its body. The blueprint level is determined by the wild level you killed.

U CRAFT 'EM!!! seriously. That's how you get 'em

They have shield that block damage by hit counts, so its best to use a fast firing dino(velonsasaur) or auto weapon to destory one, they drop blueprint of themself

You can also craft a level one in any terminal around the city if you want one quickly

Each on I kill only seems to be worse than the one you craft at a terminal, even the max lvl ones. Official settings.