What are transitional fossils and why are they important to the fossil record?

1 Answer

Transitional fossils are believed to be the preserved evidence of transitional forms of organisms, the so called missing links which provide support to the theory of descent with modification.


A transitional fossil is a term used to describe a fossil that shows a transitional form of two different species. The transitional fossil will show a combination of traits from the species that preceded it and the species that followed it. One of the best example of a transitional species is Archaeopteryx, which shows the transition from dinosaurs without feathers to modern birds.


Transitional fossils are predicted by the Darwinian theory of evolution. This theory also known as descent with modification states that all life started from a common cell and has gradually changed to all forms of life present on earth today. The transitional fossils predicted by descent with modification have not been found.

As the theory states that organisms have gradually changed from one from to another form transitional fossils should be found that show evidence of the transitional forms of the organism. In using the fossil record to support the Darwinian theory of evolution finding these transitional fossils is important. There are Questions about the truth of the Darwinian theory of evolution because of the lack of transitional fossils showing gradual changes from one form to another form.

The theory of evolution by punctuated equilibrium as proposed by Stephen Jay Gould is an attempt to explain the lack of these predicted transitional fossils. As stated by T.S.Kemp it is impossible to trace a transition form one genus to another page 319 Mammal like reptiles.