The answer to this question probably depends on the availability and locality of the dinosaur’s food supply. In general, to support a larger weight, the bone sizes also increase, or else they would literally break under the animal’s own weight. Plus, as the bones become thicker to support the increasing weight, the animal would become more and more cumbersome, limiting its ability to obtain food. Thus, for each dinosaur species, there was probably a definite limit to its size.