Editing Comparative anatomy (section)

==Concepts==
[[File:Affe-tyson.jpg|thumb|A drawing by [[Edward Tyson]]|alt=A drawing by Edward Tyson|311x311px]]<!--{{multiple image | direction=vertical | width= 282 | image1= Human_Heart_vs_Chicken_Heart.png | caption1= The human heart (left) and chicken heart (right) share many similar characteristics. Avian hearts pump faster than mammalian hearts. Due to the faster heart rate, the muscles surrounding the ventricles of the chicken heart are thicker. Both hearts are labeled with the following parts: 1. Ascending Aorta 2. Left Atrium 3. Left Ventricle 4. Right Ventricle 5. Right Atrium. | image2= Braus 1921 80.png | caption2=A 20th century illustration comparing the bone-structures of a human and a dog.}}-->

Two major concepts of comparative anatomy are:
# [[homology (biology)|Homologous structures]] - structures (body parts/anatomy) which are similar in different species because the species have [[common descent]] and have evolved, usually divergently, from a shared ancestor.  They may or may not perform the same function. An example is the forelimb structure shared by [[cat]]s and [[whales]].
# [[Analogy (biology)|Analogous structures]] - structures similar in different organisms because, in [[convergent evolution]], they evolved in a ''similar environment'', rather than were inherited from a recent common ancestor. They usually serve the same or similar purposes. An example is the streamlined torpedo body shape of [[porpoise]]s and [[shark]]s. So even though they evolved from different ancestors, porpoises and sharks developed analogous structures as a result of their evolution in the same aquatic environment. This is known as a [[homoplasy]].<ref>{{cite book |title=Vertebrates: Comparative Anatomy, Function, Evolution | vauthors = Kardong KV |publisher=McGraw-Hill Education |year=2015 |isbn=978-0-07-802302-6 |location=New York |pages=15–16}}</ref>