Tiktaalik
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Tiktaalik is an extinct genus of fish which lived around 375 million years ago[1].
Unlike modern fish, Tiktaalik had a neck; it both had gills and lungs; it had bones in its fins that resemble the bones in the upper arm, forearm and wrist of land vertebrates; it had ribs that could support its body weight on dry land. [2][3] Given its "neither-fish-nor-fowl" attributes, many scientists see Tiktaalik as a transitional form in the evolution of tetrapods (four-limbed vertebrates, i.e. amphibians, reptiles, birds, and mammals). Scientists call it "the most compelling examples yet of an animal that was at the cusp of the fish-tetrapod transition".[4]
Na na na na na na, we can't hear you[edit]
“”What evolutionists fail to see however is that Tiktaalik is actually a fish, much as Archaeopteryx is a bird.
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—Generic creationist response[5] |
Creationists claim that 397-million-year-old (compare to Tiktaalik's age of 375 million years) fossilized footprints found in Poland show that Tiktaalik could not reveal a transition between water and land animals.[6] However, this argument is based on misunderstanding evolution as a linear progression. Augustine of Hippo's Great Chain of Being is fictional. There is no real reason why a primitive (i.e., resembling the ancestral) morphology could not survive to recent times (hey, coelacanth, how's it going?)
Plausible explanations for the 397-ma fossils include:
- The fossils just aren't tetrapod footprints, but something else.
- The vertebrates made at least two transitions to land, not just one. The members of the transition represented by the Polish tracks all died, but Tiktaalik's descendants are modern tetrapods.
- Tiktaalik and kin have an as yet unknown fossil record which will put their common ancestor with tetrapods between that of tetrapods and lungfish.
Related fossils[edit]
The transition from water to land is bridged by several transitional fossils, ranging from amphibian-like fish to fish-like amphibians. One research article[7] gives this list (with the caution that, like most things in evolution, there is no simple straight line):
- Eusthenopteron
- Panderichthys
- Tiktaalik
- Tulerpeton
- Elginerpeton
- Designathus
- Ventastega
- Metaxygnathus
- Acanthostega
- Ymeria
- Ichthyostega
- Hynerpeton
- Parmastega
- Watcheeria
- Pederpes - From smack in the middle of "Romer's Gap
", where the tetrapod fossil record goes out to lunch for some 20 million years
- Greererpeton
- Crassigyrinus
- Baphetes
- Balanerpeton
- Denderpeton
- Silvanerpeton
- Proterogyrinus
- Eoherpeton
- Weslothiana
- Eucritta
External links[edit]
References[edit]
- ↑ Fossil fish bridges the evolutionary gap between animals of land and sea. October 16, 2008
- ↑ Why is Tiktaalik called the "fishapod"?
- ↑ The Real Darwin Fish, why creationists hate Tiktaalik.
- ↑ John Noble Wilford. Scientists Call Fish Fossil the 'Missing Link'.
- ↑ Creation wiki - Tiktaalik
- ↑ http://creation.com/polish-tetrapod-footprints-trample-tiktaalik
- ↑ Figure 4d in Per E. Ahlberg, Jennifer A. Clack, Ervns Lukevis, Henning Blom & Ivars Zupi: "Ventastega curonica and the origin of tetrapod morphology". Nature 453, 1199-1204 (26 June 2008). doi: 10.1038/nature06991