Figure 5. Frequency distribution of dinosaur species body size for six major time periods: (a) Late Triassic; (b) Early Jurassic; (c) Middle Jurassic; (d) Late Jurassic; (e) Early Cretaceous; and (f) Late Cretaceous.

The Early and Middle Jurassic were best fitted by unimodal distributions; the Early Cretaceous by a bimodal distribution. The Late Triassic, Jurassic and Cretaceous were all best fitted by negatively-skewed multi-modal distributions (see Table 2).