Multiple choice

In vertebrate evolution, reptiles were able to move completely on land due to

  1. their scales

  2. the amniotic egg

  3. increase in size

  4. availability of food
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The amniotic egg is the key evolutionary innovation that allowed reptiles (and later birds and mammals) to reproduce on land without dependence on water environments. The amniotic egg contains its own water supply and protects the embryo from desiccation. Scales provide protection but don't enable terrestrial reproduction. Increased size and food availability are not specific adaptations for land reproduction.

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