Question

Which of the following characteristics is not shared by extant birds and extant reptiles?

a. Endothermic metabolism
b. Amniotic eggs
c. Vertebrae
d. Scales containing keratin
e. Pharyngeal clefts in the embryo

Answer 1

Extant birds and extant reptiles do not share endothermic metabolism; birds are endothermic while reptiles are generally ectothermic.

Step-by-step explanation:

The characteristics not shared by extant birds and extant reptiles is endothermic metabolism. While both groups lay amniotic eggs and possess vertebrae, extant reptiles do not share the endothermic metabolic process with extant birds. Reptiles generally have an ectothermic metabolism, meaning they regulate their body temperature through external means, unlike birds.

While both groups may have scales containing keratin (birds in the form of feathers and reptiles as part of their skin), and both exhibit pharyngeal clefts during the embryonic development stages, the key difference is how they generate and maintain their body temperature.