Key Earth Science Links
Devonian Period—Lobefins, lungfish, amphibians, and tetrapod evolution
Recent Findings Fishes with Legs, Devonian Times. Good summary of the fossil evidence for the evolution of fish to amphibians. A table is provided that includes the names of the known "transitional" tetrapods (four-legged animals) with links to summaries and Web sites for those animals. For example, you can choose More about lobefin fishes (including Eusthenopteron), Icthyostega,or Acanthostega for information about two of the more famous Devonian transitional tetrapods.
Terrestrial Vertebrates, Tree of Life Web Project. Technical summary of the evolution of terrestrial vertebrates with an introduction, classification, characterization, information on the evolution of limbs, and a cladogram from which you can pick specific taxon.
Evolution—Fish with Fingers, PBS. A short (3 minutes, 48 seconds) video that requires a Quicktime or Realplayer plug-in, which discusses Acanthostega and the evolution of fish to amphibians. Based on the PBS video series "Evolution."
Tetrapods--The Fossil Record, University of California, Berkeley. Short description of tetrapod (four-legged animal) evolution, including amphibians.
Introduction to the Sarcopterygii--From Fins to Legs, University of California, Berkeley. Short description of the lobefin fish (Sacropterygii) with a cladogram that links to related lineages.
Use and Abuse of the Fossil Record-The case of the “Fish-ibian.” Creation and Intelligent Design Watch, Penny Higgins. Short discussion of the transition from fish to amphibians The 10-page discussion is written to counter claims that there are no such transitions in the fossil record. The website steps through the process of using cladograms (with helpful terms for biological classification), defining amphibians, .shows what would and wouldn’t fossilize in fish and amphibians, and then uses cladistics to compare several pertinent fossils and demonstrate where transitional elements of evolution fall on a cladogram, vs. the straight-line evolution often inferred in the media or assumed by the public.
Tiktaalik…the origin of the tetrapod limb. Shubin and others, 2006. Technical journal article from Nature on the fossil, Tiktaalik roseae, a Devonian fish with well preserved pectoral fins. Contains a nice cladogram with illustrations of known fossil pectoral fins and limbs with digits for the Devonian transition from fish to amphibians, as well as good issllustrations of shoulder girdles comparisons and humeri comparisons (which are sometimes unfortunately forgotten in K-16 discussions of the fish to amphibian transition).