Question

Which one of the following in birds indicates their reptilian ancestry?

• A. Scales on their hindlimbs
• B. Four-chambered heart
• C. Two special chambers crop and gizzards in their digestive tract
• D. Egg with a calcareous shell

Answer 1

The correct option is A Scales on their hindlimbs

• The dry skin of reptiles is covered with scales to prevent water loss as an adaptation to terrestrial life.
• The hind limbs of birds also have scales which confirm their reptilian ancestry.
• The reptilian heart is three chambered with two atria and one ventricle, while birds have a four-chambered heart with two atria and two ventricles. The crop is the enlarged part of the esophagus, which stores the food and is an avian adaptation to reduce their exposure to predators.
• Likewise, modern birds are toothless to trim the weight of the head as a flight adaptation. The absence of the tooth is compensated by the presence of gizzard wherein food is chewed.

Thus, the correct answer is option A.