Sooo easy! I tamed one BEFORE I unlocked the saddle! Just get a ballista burret, load it with trang arrows, and shoot a bronto! It will attack you, so hide behind a appropriate rock or cliff and shoot again, and again, and again! When it runs from you, continue shooting. It will knock out and feed it mejoberries!
I recommend taming this as soon as you get the saddle! They’re a super easy tame, use a crossbow with about 25-80 depending on the level, hop on a pteranodon after shooting it once, land, hop off, shoot it more, rinse and repeat till KO. If you have boosted taming time, just use mejos and it’ll work fine. Up if this helped!