What is believed to be the most significant result of the evolution of the amniotic egg?

• A. It allowed vertebrates to reproduce on land without the need for water.
• B. It led to the evolution of endothermy in mammals.
• C. It enabled the development of lungs in amphibians.
• D. It resulted in the loss of the notochord in adult vertebrates.

Answer: (A)

Verified step by step guidance

1. Understand the structure and function of the amniotic egg: The amniotic egg is a specialized adaptation that includes membranes such as the amnion, chorion, yolk sac, and allantois. These structures protect the embryo, provide nutrients, and manage waste, enabling development in terrestrial environments.
2. Recognize the evolutionary significance: The amniotic egg allowed vertebrates, specifically reptiles, birds, and mammals, to reproduce on land without relying on water for the development of their embryos, unlike amphibians which require aquatic environments for reproduction.
3. Eliminate incorrect options: Evaluate each answer choice. For example, the development of lungs in amphibians is unrelated to the amniotic egg, as amphibians do not produce amniotic eggs. Similarly, the loss of the notochord in adult vertebrates is a separate evolutionary event and not linked to the amniotic egg.
4. Focus on the correct answer: The most significant result of the evolution of the amniotic egg is its role in enabling vertebrates to reproduce on land without the need for water, which was a major evolutionary step for terrestrial life.
5. Conclude with the broader impact: The evolution of the amniotic egg contributed to the diversification of vertebrates on land, allowing them to occupy a wide range of terrestrial habitats and reducing dependence on aquatic environments for reproduction.