When we look at the anatomy of some animal groups, we will find similarities on the structure of certain parts of the body. For example, if we compare the front legs of bird, bat, whale, cat, horse, and human, then there are similarities in components of the movement organs. The front movement organs of those animals are composed of long bone, radius and ulna bone, wrist bone, palm bone, and finger bone. Generally, each bone in each animal has different in size.
The similarities of the structure of the animals show the relation between them. It is assumed that the animals come from the same ancestor. shape and size differences on certain organ structure are resulted from functional adaptation process to different habitat. The same basic structure of some organs which have different function is called homologous. The example of it can be found in circulatory and urogenital system of vertebrate.
The homologous of front movement organs of some species
- a.Fossil Archaeopteryx
- b.Comparison between dinosaur (left) and Archaeopteryx (right)
Source: Biology. The unity and diversity of life, 2004