Comparative Anatomy Notes

Comparative Anatomy - is the study of similarities and differences among structures of living species.

Homologous Structures - are body parts of organisms that are similar in structure and position but different in function.

Look at what is the same and what is different…

Analogous Structures - are body parts that perform a similar function but differ in structure.

Notice the wings are very different, but both are used to fly…

Vestigial Structures - are body parts that have lost their original function through biologic evolution.

Whales have a number of vestigial structures that would have been fully functional in their land-living ancestors. These include the pelvic girdle, hind limbs and finger muscles.

Vestigial Structures in Whales Whales have a number of vestigial structures that would have been fully functional in their land-living ancestors. These include the pelvic girdle, hind limbs and finger muscles.

Vestigial Structures in Humans Charles Darwin listed a number of human vestigial features in his book The Decent of Man (1890). Muscles of the ear Appendix The tail bone Body hair Wisdom teeth

Q.1 Infer: What is the function of the bones in bats that are homologous to finger bones in humans? Q.2 Infer: Why does a vestigial pelvis show that the ancestors of the modern whale once had legs? Q.3 How do Homologous Structures and Vestigial Structures provide evidence for biologic evolution?

Q.4 Infer: Based on these notes and the evidence you see here, which animal do you think we (humans) are most closely related to – the chicken or the bat?