READ: Important Vocabulary Terms

Comparative anatomy is the study of the similarities and differences in the structures of different species. Similar body parts may be homologies or analogies. Both provide evidence for evolution.

Homologous structures are structures that are similar in related organisms because they were inherited from a common ancestor. These structures may or may not have the same function in the descendants.

Analogous structures are structures that are similar in unrelated organisms. The structures are similar because they evolved to do the same job, not because they were inherited from a common ancestor.

A common ancestor is an ancestor organism that two or more modern organisms evolved from.

Vestigial structures are physical structures in an organism that have lost their use through evolution. They suggest that an organism changed from using the structure to not using the structure, or using it for a different purpose.

An embryo is an animal or plant in its earliest stages of development. After fertilization occurs, the fertilized egg is called an embryo.

Embryology is the study of how organisms develop.

Comparative embryology is the study of the similarities and differences in the embryos of different species. Similarities in embryos are evidence of common ancestry.