Scientists have hypothesized that the common ancestors of birds and mammals, possessed three-chambered hearts (two atria, one ventricle). Birds and mammals, however, are alike in having four-chambered hearts (two atria, two ventricles). Which of the following statements best describes the four-chambered hearts of birds and mammals?
A) they are morphological homologies
B) they exhibit molecular homology
C) they are morphological analogies
D) they are the result of shared ancestry

Question

Quizplus · Accepted Answer

The four-chambered hearts of birds and mammals are morphological analogies because they are similar in function and structure but did not arise from a common ancestor with a four-chambered heart. Instead, this trait evolved independently in the two lineages, demonstrating convergent evolution rather than shared ancestry.

Scientists Have Hypothesized That the Common Ancestors of Birds and Mammals