How does transitional forms support evolution

Modern horses members of the genus Equus , which also includes donkeys and zebras have just one toe—the hoof. However, the ancestors of modern horses, which lived more than 50 million years ago, had four toes. We know this from fossils of the earliest horses, like those of Eohippus also known as Hyracotherium. In fact, the fossil record contains many examples of these, represented by three-toed Archaeohippus and Parahippus on the tree below.

In this case and many others, fossils bear transitional features that provide strong evidence illustrating how major evolutionary changes occurred. Learn more about transitional features in Understanding macroevolution through evograms , a module exploring five examples of major evolutionary transitions in the fossil record. Distribution in time and space. Subscribe to our newsletter.

Email Facebook Twitter. Lines of Evidence: The Science of Evolution. Presenting cladistic thinking to biology majors and general science students. Hennig W. Phylogenetic systematics trans. Davis and R. Urbana: University of Illinois Press; The quality of the fossil record: implications for evolutionary analyses. Annu Rev Ecol Syst. Padian K. Trickle-down evolution: an approach to getting major evolutionary adaptive changes into textbooks and curricula.

Integr Comp Biol. Article PubMed Google Scholar. Padian K, Angielczyk KD. Scientists confront intelligent design and creationism. New York: Norton; Prothero DR. Evolution: what the fossils say and why it matters.

New York: Columbia University Press; Ruse M. Monad to man: the concept of progress evolutionary biology. Cambridge: Harvard University Press; Texas State Board of Education Meeting. Amendments of Don McLeroy. Vardiman L. In Ashton JF, editor. In six days: why 50 scientists choose to believe in creationism. Download references. National Center for Science Education, P. You can also search for this author in PubMed Google Scholar.

Correspondence to Louise S. Reprints and Permissions. Mead, L. Transforming Our Thinking about Transitional Forms. Evo Edu Outreach 2, — Download citation. Received : 02 March Accepted : 10 March Published : 16 April Issue Date : June Anyone you share the following link with will be able to read this content:.

Sorry, a shareable link is not currently available for this article. A very small percentage of animals that have lived and died ever became fossils. Thus, many pieces of the puzzle are missing; some will never be found. Nonetheless, we have many, many fossils that illustrate evolutionary transitions between fish and amphibians, between reptiles and mammals, between dinosaurs and birds, and in many lineages such as whales and horses.

And new fossils continue to reveal transitional forms that some said don't exist. Learn More What Killed the Dinosaurs? Web Activities. About the Project.