What are Amniotes?
Amniotes are tetrapod vertebrates that include reptiles, birds, and mammals. They evolved during the Carboniferous period and are characterized by their ability to reproduce on land through the development of amniotic eggs or internal gestation.
Diagram of an amniotic egg showing its protective membranes.
Key Features of Amniotes
Amniotic eggs with protective membranes
Thicker keratinized skin
Costal respiration
No metamorphosis
The fossil of Archaeopteryx, an early amniote and ancestor of modern birds.
Evolutionary Significance
The evolution of amniotes marked a major transition in vertebrate history. Their adaptations allowed them to colonize terrestrial environments fully and diversify into various ecological niches.