Implications of body-mass estimates for dinosaurs

ABSTRACT

Body-mass estimates have been made for 220 of the over 300 generally accepted dinosaur genera. The 1–10 ton body-mass category is the modal one for all dinosaur genera, dinosaurs on nearly every continent, dinosaurs during most stages of the Mesozoic, and dinosaurs in two of the three peak historical periods of dinosaur discoveries. Carnivorous dinosaurs were much smaller than herbivores during the Late Jurassic and again in the Late Cretaceous: at other times the two were roughly equivalent in mass. In terms of discovery of dinosaur genera over time, there has been a simultaneous increase in proportion of very small (under 10 kg) dinosaurs and a relative decline in giant dinosaurs (10–100 tons). This suggests that early researchers tended to collect giant dinosaurs.