Comparative Anatomy:

Anatomical similarities between species grouped in the same taxonomic category bring another support to the theory of the Descent with modification.

Following structures provide evidences for evolutionary concept of Darwin. Homologous structure. Homologous organs are functionally different but structurally alike.

Similarity in characteristics resulting from common ancestry is known as homology, and such anatomical signs of evolution are called homologous structures.

Example.

Forelimbs of different mammal e.g. the arms of human, forelegs of cats, flippers of whales, wings of bats, have the same skeletal elements although these appendages have very different functions.

Divergent evolution.

The basic similarity of the structure is the consequence of the descent of all mammals from a common ancestor and are variations on a common anatomical theme that has been modified for divergent functions.

Remodeling Process.

Comparative anatomy supports that evolution is a remodeling process in which ancestral structures that functioned in one capacity become modified as they take on new functions.

Example.

The flower parts of a flowering plant are homologous. They are considered to have evolved from leaves, to form sepals, petals, stamens and carpels and adapted different functions Analogous Structure. These are functionally alike but structurally different e.g. wings of bat, birds and insects etc.

Convergent evolution.

The same function from different structures may be related to same habitat. This is convergent evolution..

Vestigial Structures.

The oldest homologous structures are vestigial organs, rudimentary structures of marginal, (if any), use to the organism. Vestigial organs are historical remnants of structures that had important functions in ancestors but are no longer essential presently. For instance, the skeletons of whales and some snakes retain vestiges of the pelvis and leg ones of walking ancestors. Vermiform appendix in carnivores, ear muscles in man etc.