Tiktaalik and Mudskippers

Neil Shubin, one of the discoverers of Tiktaalik, the Devonian transitional fishapod from the Canadian Arctic, writes about the adaptations of those ancient fish, and compares them to adaptations that we see in some modern fish that venture onto land.

Edge: THE “GREAT” TRANSITION by Neil Shubin

Several different kinds of fish climb trees; in addition, there are many different species of fish that breathe air, live part of their life on land, and walk about. The boundary between water and land is quite porous and bridged by modern fish from around the world. In fact, the adaptations we see in the fossils of the fish-tetrapod transition seem almost trivial in comparison to the living animals.Mudskippers and the other walking fish are all very interesting, but are they extraordinary in an evolutionary sense? No, they are not, and the reason is instructive.

Hopping, climbing, and breathing fish are just animals that have evolved to live in different kinds of aquatic and subaereal habitats. They are able to breathe air, hop, or climb because of subtle changes to their bodies; no revolutionary changes are needed. In evolutionary terms, the only way they will be notable is if their lineage is prolific and their descendants do great things. The relatives of the fish and tetrapods from Canada and Greenland were prolific; they are part of a trunk of the evolutionary tree that gave rise to every tetrapod—every bird, mammal, reptile, and amphibian. The mudskipper has a long way to go, and many hurdles to leap, before we will know whether its part of the evolutionary tree is special.

If paleontologists 300 million years from now dig up the remains of a mudskipper, they will write chapters about its role in a “great” transition only if its part of the evolutionary tree has branched into many twigs. The mudskipper will get extra special treatment if one of its evolutionary branches leads to the paleontologists’ own species.

Now there’s a thought. What would terrestrial descendants of mudskippers, 300 million hence, look like?

Comments

  1. The Sanity Inspector wrote:

    What would terrestrial descendants of mudskippers, 300 million hence, look like?

    One can only guess.

    Posted 11 May 2006 at 4:53 pm

  2. The Sanity Inspector wrote:

    And guess again.

    Posted 11 May 2006 at 5:37 pm

  3. commissar wrote:

    hahaha, very good.

    Posted 11 May 2006 at 5:45 pm

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