Why were prehistoric era animals so gigantic in comparison to animals from the “modern era”

Question

Why were prehistoric era animals so gigantic in comparison to animals from the “modern era”

In: 1281

Answer 1

The climate during the age of dinosaurs was very different than now.

The Earth back then had higher average temperatures and the Oxygen content of the atmosphere was much higher.

Plant life was also more abundant in that era so there was much more food.

These factors supported much larger animals and insects, and an evolutionary arms race between predators and prey likely drove dinosaurs to reach immense size.