Why did many dinosaurs grow to such enormous sizes?
Large animals benefit from the economies of scale. Their bodies require less energy per kilogram of mass, and their sheer size makes adults difficult to attack. Being tall also allows them to eat food out of the reach of smaller animals. The ratio of adult to newborn size was much greater among dinosaurs than mammals. We do not know why, but some palaeontologists think that dinosaurs may have continued growing throughout their adult lives, so the largest dinosaurs were also the oldest. Large size may also have allowed dinosaurs to maintain a high body temperature, without the need to generate heat metabolically as mammals and birds do today. Australian zoologists have demonstrated that in crocodiles – today’s heftiest living reptiles – large individuals are consistently warmer, and show less fluctuation in body temperature, than smaller ones. Though large and warm dinosaurs would have enjoyed the speed and endurance associated with birds and mammals today, large dinosaurs in warm clima
