amniotëve

Amniotes are a clade of tetrapod vertebrates comprising the reptiles, birds, and mammals. The defining characteristic of this group is the presence of the amniotic egg, a key innovation that allowed vertebrates to reproduce on land. The amniotic egg is distinguished by several extraembryonic membranes: the amnion, chorion, and allantois, as well as a protective shell or leathery covering. These membranes provide support, protection, and facilitate gas exchange and waste removal for the developing embryo, freeing it from dependence on an aquatic environment.

The evolutionary divergence of amniotes from their amphibian ancestors occurred during the Carboniferous period. This transition marked a significant step in the colonization of terrestrial habitats by vertebrates. Reptiles were the first major group to evolve, followed by the divergence of synapsids, which eventually led to mammals, and diapsids, which gave rise to modern reptiles and birds.

The presence of the amniotic egg allowed amniotes to lay their eggs on land, reducing competition and predation pressures found in aquatic environments. This adaptation played a crucial role in the diversification and success of amniotes, enabling them to inhabit a wide range of terrestrial ecosystems. Modern amniotes exhibit a vast array of forms and lifestyles, reflecting their long evolutionary history and adaptation to diverse environments.