List of transitional features

This page is intended as a response to the creationist claim that there are no transitional features, that is that there are no examples in the fossil record of features that are morphologically intermediate between primitive and derived (advanced) forms. Use of this claim can be seen on page 64 in the creationist publication Life--How Did It Get Here? By Evolution or By Creation?

Despite the claim, there are examples of transitional features from the fossil record:

Fish to tetrapod transition

Panderichthys rhombolepis fore and hind limbs are transitional between Eusthenopteron fins and leg-like Acanthostega gunnari limbs.
Panderichthys hyomandibula and spiracle, precursors to the ear on land animals, are a combination of Eusthenopteron and Acanthostega gunnari structures.
The Late Devonian species Tiktaalik rosae exhibits many traits that are transitional between fish and tetrapods such as half-fish, half-tetrapod limb bones and having both tetrapod lungs and fish gills.

Reptile to mammal transition

Many of the species within the link between mammal-like reptiles and mammals exhibit transitional skull and jaw structures and teeth.

Reptile to bird transition

Archaeopteryx's range of motion in the shoulder joint was intermediate between Theropods and birds.
Hesperornis lacked teeth on the upper jaw and may have had a beak on the upper jaw only, making it intermediate between the reptile jaw and bird beak.

Species-to-species transitions--mammals

Protitanotherium had a horn size intermediate between Manteoceras and Brontotherium. All are members of the extinct family Brontotheriidae.

Basilosaurus had hind limbs intermediate between Ambulocetus and modern cetaceans.
Pakicetus had hearing organs intermediate in appearance between land mammals and aquatic cetaceans.
Rodhocetus nostril position is intermediate between Pakicetus and modern whales.

References

Myers, P. Z. (2005, Dec 22). Panderichthys rhombolepis. Retrieved on 2008-04-28.
Carey, Bjorn (19 January, 2006). Human Ears Evolved from Ancient Fish Gills. LiveScience. Retrieved on 2008-04-28.
Cuffey, Clifford A. (June 7, 2001). The Fossil Record: Evolution or “Scientific Creation”. GCSSEPM. Retrieved on 2008-04-28.
Scileppi, Elyse. Wing Flexibility:. Retrieved on 2008-04-29.
(1/16/05). Aves: Ornithothoraces. Palaeos. Retrieved on 2008-04-30.
MacFadden, Bruce J. Thunder Beasts, Sexual Selection, and Extinction. Pony Express, Volume 10, Number 1, 1st Half 2001. Retrieved on 2008-04-29.
Thewissen, J. G. M., et. al. (May 22, 2006). Developmental basis for hind-limb loss in dolphins and origin of the cetacean bodyplan. PNAS | May 30, 2006 | vol. 103 | no. 22 | 8414-8418. Retrieved on 2008-04-29.
Thewissen, J. G. M., et. al. Origin of underwater hearing in whales. Nature 361, 444 - 445 (04 February 1993); doi:10.1038/361444a0. Retrieved on 2008-04-29.
University of Bristol. Cetacean Palaeobiology. Retrieved on 2008-04-29.

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