Why Were Dinosaurs So Big?

The biggest dinosaurs were way bigger than any land animal today - how did they get so enormous? Watch this video to find out, or read our explanation below!

There Was Probably More Food

Back when the dinosaurs walked the Earth, the climate was different - it was hotter, and there was more CO2 in the atmosphere. All of this means there was probably more plant life, meaning more available food for animals to eat. Growing super large requires lots and lots of food, so having more plant life may have meant larger animals could be supported.

Dinosaurs Had Hollow Bones

Some dinosaurs had air pockets inside their bones, meaning their overall bone density was a lot lower than today’s large mammals (modern-day birds also share this trait, which probably helps them fly!). Lighter bones meant lighter bodies. A Tyrannosaurus Rex would weigh only half as much as an elephant of the same size.

Dinosaurs Laid Eggs

Mammals give birth to live young, and the larger the mammal, the longer the pregnancy. Elephants are pregnant for nearly 2 years! Dinosaurs, on the other hand, laid eggs, which requires a lot less time and energy, removing the size constraint placed on mammals by live birth.