In my Barbarian Conqueror King setting, some dinosaurs serve as beasts of burden, particularly Ankylosauruses, Triceratops, Edmontosauruses and even Alamosauruses. How much can they carry?
Normal load is generally 0.020 of body weight for quadrupeds and 0.033 of body weight for bipeds.
A heavy horse (2,000lbs) has a normal load of 40 stone. A donkey (500lb) has a normal load of 10 stone.