In this time period, Europe, Asia, and North America were located in the tropical region. When Euramerica and Gondwana merged to form Pangea, it caused the airwaves to change and the water patterns formed things like glaciers. This cooled the air and doubled the amount of oxygen, causing insects to be the size of dogs.
The Earth's atmosphere was 35% oxygen. This huge amount of oxygen allowed larger animals to live.
The Earth's atmosphere was 35% oxygen. This huge amount of oxygen allowed larger animals to live.