Fossils provide the direct evidences of organic evolution. Fossils may be entire organisms buried in sediment or snow, small part of ancient organisms or impression of extinct organisms, ancient leaf or stem. Morphology is the study of form and structure in organisms. Comparative study of homologous and analogous organs provide evidence of evolution under functional anatomy (tectology). Comparative embryology (study of embryo) provides evidence of organic evolution which is based on basic laws or principles of embryonic development (the biogenetic law or recapitulation theory). Vestigial organs are degenerate, non-functional and rudimentary organs correspond to fully developed and functional organs of related organisms. They also afford to provide evidences for organic evolution. But, among them most evident and direct proof of evolution is provided by fossils.