Need a tip for these things? Avoid them till you can get a rex or a spino saddle and the creature and just look for them. Avoid swamps and redwoods. For taming:

Get a rex if you have spares, find a male, kill it, get its pheromone, find a female, get her to 100 hp, use the pheromone on the rex and have her impregnate your rex and just fill your rex with meat. About how to get levels for the baby before it hatches - it has cravings here and there where it asks for certain foods or rare drops.