Why did dinosaurs grow so big

    Why did dinosaurs grow so big

  • 1 Their bone structure

    Many dinosaur bones were hollowed out by air sacs extending from their lungs. This kind of light bone structure allowed more growth. See Why did Dinosaurs grow so big.

  • 2 Their bones grow in a different way

    According to one theory, the reason dinosaurs were able to grow bigger is that their bones grew in a different way than other mammals. As mammals grow larger, their bones become more rounded at the ends. However, bones in dinosaurs, reptiles and birds tend to grow wider, with flatter ends.  

  • 3 Because they were cold-blooded

    According to some theories, dinosaurs were cold-blooded and as a result they spent all the energy coming from food on growth as they didn't need to spend any of it on maintaining their body temperature.

  • 4 They had no problems living with long necks

    According to one theory, dinosaurs had a bird-like air sac system; soft tissues that eliminated some of the mechanical and physiological problems of breathing with an extra long neck. 

  • 5 Efficient lungs and respiration

    According to one theory, their efficient lungs and respiratory system helped them grow bigger.

  • 6 The way they reproduced

    Dinosaurs used to lay many eggs in nests instead of taking care of one or two offspring and investing a great deal of energy on them. This way of reproducing may have removed constraints that keep mammals relatively small by comparison.

  • 7 They swallowed food

    Dinosaurs swallowed their food instead of chewing it first. This allowed them to consume large amounts of food which in turn led to their increased size. 

  • 8 They were able to reach food easily

    Because dinosaurs had long necks, they were able to reach more food in the same feeding spot and so this contributed to their bigger size.

  • 9 Their legs can support large bodies

    The legs of dinosaurs enable them to support a much heavier weight than ordinary animals. Their legs could support up to 80 tonnes and as a result they had no problem in moving as they grew bigger. 

  • 10 There were much more plants

    According to one theory, there was much more carbon dioxide back then and the earth's temperature was hotter. This environment was good for plant growth and as a result their could have been a massive amount of plants involved.

  • 11 The larger ones couldn't be eaten

    According to one theory, the larger dinosaurs couldn't be eaten by predators and so they kept growing even larger. See also why did Dinosaurs become extinct.

  • 12 Larger bodies led to slow metabolism

    According to one theory, the large bodies of dinosaurs led to a slow metabolic rate and as a result dinosaurs needed less food to survive. This could have created a cycle of growth after the initial growth resulting from other factors.

  • 13 The big size led to even bigger size

    Some scientists believe that if a cold-blooded animal grew large enough, it would lose temperature slowly and so it could survive for longer periods of time as its body would maintain an almost constant body temperature.