To get one of these you must kill one to get its pheromone and force feed your selected dino bring a female bring her health to 10% she will impregnate your dino like the reaper taming method complete your dino cravings(sometimes will require very weird things like carch, giga eggs and very weird things so keep in mind)and POOF your tame died but you got yourself a rhynio. to get high levels it doesn't depend on the lvl of the rhynio it depends on the dino drag weight here is some of the best drag weight dinos (giga,charch,diplodocus,brontos, and pretty much anything that is very big)