The cliff method works best for these beauties. Items needed are: necessary amount of biotoxin, crossbow ( two is better ), flying mount ( optional ), necessary amount of tranq arrows to knock it out, stone arrows, a high damage projectile, and an area with cliffs, rocks, and a bunch of stegos.

First, if needed, use the flyer to lure the allosaur(s) to a cliff or tall rock where they can’t reach you, then stay on the cliff. Then, simply shoot it with tranq arrows until knocked out. If it gets too low on health, leave it be and wait for it to heal. If it loses interest in you hit it with a regular arrow or any low damage projectile to get it to aggro and shoot it w tranqs until unconscious. Now here’s where thestegos come in. Stand on a tall rock unreachable by the stegos and kill them with a crossbow or other projectile and here you have a pretty easy source of prime meat. Keep your allo in check with biotoxin and you’ll have a new tame in no time!