Which of These Characteristics Added Most to Vertebrate Success in Relatively

Question

Which of these characteristics added most to vertebrate success in relatively dry environments?
A)the shelled, amniotic egg
B)the ability to maintain a constant body temperature
C)two pairs of appendages
D)bony scales
E)a four-chambered heart

Accepted Answer

The shelled, amniotic egg allowed embryos to develop outside of water, providing vertebrates with the ability to reproduce and survive in dry environments. This was a key adaptation that allowed for the evolution of reptiles, birds, and mammals. The ability to maintain a constant body temperature, having two pairs of appendages, bony scales, or a four-chambered heart are all important adaptations, but they did not contribute as significantly to success in dry environments as the amniotic egg.