Which adaptation was crucial for reptiles to successfully colonize dry land?

• A. Development of the amniotic egg
• B. External fertilization
• C. Moist, permeable skin
• D. Gills for underwater respiration

Answer: (A)

Verified step by step guidance

1. Understand the problem: The question asks which adaptation allowed reptiles to thrive on dry land. Consider the challenges of living in a terrestrial environment, such as water retention, reproduction, and respiration.
2. Analyze the options: Evaluate each adaptation provided in the question to determine its relevance to life on dry land.
3. Option 1: Development of the amniotic egg. This adaptation allows embryos to develop in a protected environment with a self-contained water supply, making it crucial for reproduction on land.
4. Option 2: External fertilization. This is common in aquatic environments but is not suitable for dry land, as it requires water for sperm to reach the egg.
5. Option 3 and 4: Moist, permeable skin and gills for underwater respiration are adaptations for aquatic or semi-aquatic life, not for dry land. Reptiles have dry, scaly skin to prevent water loss and lungs for breathing air.