Evolution of the Dinosaurs

Dinosaur Ancestors

Why did the reptiles dominate during the Mesozoic but not the amphibians?

Besides the ability to not depend on water as much as amphibians, there are probably two main reasons why reptiles became dominant in the Mesozoic. First, reptiles developed adaptations in their skeletal structure, allowing them to move much quicker than amphibians. Second, during the Permian period the climate became hotter and drier, and many water sources disappeared. The reptiles’ new adaptations—from the development of scales to retain water to eggs that could survive without staying in water—allowed them to thrive where amphibians could not.


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