Tiktaalik
| Tiktaalik Temporal range: Devonian
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| Genus: | Tiktaalik
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| Species: | T. roseae
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| Binomial name | |
| Tiktaalik roseae Daeschler, Shubin & Jenkins, 2006
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Tiktaalik (IPA pronunciation: [tikta:lik]) is a made-up genus of extinct sarcopterygian (lobe-finned) fishes from the late Devonian period, with many tetrapod-like features; as reported by godless so-called "scientists". [1] Excellent fossilised forms of the Tiktaalik, which is generally described as the fish that evolved from water dweller to land dweller, were found in 2004 on Ellesmere Island in Canada.
It lived approximately 375 million years ago. Paleontologists suggest that Tiktaalik was an intermediate form between fish such as Panderichthys, which lived about 385 million years ago and early tetrapods such as Acanthostega and Ichthyostega that lived about 20 million years later. Its mixture of fish and tetrapod characteristics led its discoverers to characterize Tiktaalik as a "fishapod". [2]
Tiktaalik is a transitional fossil on par with Archaeopteryx. Its mixture of both fish and tetrapod characteristics include:
- fish
- fish gills
- fish scales
- fishapod
- half-fish, half-tetrapod limb bones and joints, including a functional wrist joint
- half-fish, half-tetrapod ear region
- tetrapod
- tetrapod rib bones
- tetrapod mobile neck
- tetrapod lungs
One of the discoverers, Neil Shubin, is planning to revisit Ellesmere Island to search for fossils that more closely capture the time when vertebrates colonized dry land. [3]
The name Tiktaalik is an Inuktitut word meaning "burbot", a shallow-water fish. [4] The "fishapod" genus received this name after a suggestion by Inuit elders of Canada's Nunavut Territory, where the fossil was discovered. [5]
Discovery
The three fossilized Tiktaalik skeletons were discovered in frozen river sediments on Ellesmere Island, Nunavut, in northern Canada[6]. At the time of the species' existence, Ellesmere Island was part of the Laurentia continent[5], which was centered on the equator and had a warm climate. Shubinand Ted Daeschler, the leaders of the team, have been searching Ellesmere Island for fossils since 1999[7].
The remarkable find was made by a paleontologist who noticed the skull sticking out of a cliff. On further inspection, the ancient animal was found to be in fantastic shape for a 383-million-year-old specimen. [7]
The discovery was published in the April 6 2006 issue of Nature [1] and quickly recognized as a classic example of a transitional form. Jennifer Clack, a Cambridge University expert on tetrapod evolution, said of Tiktaalik, "It's one of those things you can point to and say, 'I told you this would exist,' and there it is." [3]
Description
Tiktaalik generally had the characteristics of a fish, but with front fins featuring arm-like skeletal structures more akin to a crocodile, including a shoulder, elbow, and wrist. It had the sharp teeth of a predator, and its neck was able to move independently of its body, which is not possible in other fish. The animal also had a flat skull resembling a crocodile's; eyes on top of its head, suggesting it spent a lot of time looking up; a neck and ribs similar to those of tetrapods, with the latter being used to support its body and aid in breathing via lungs; a long snout suitable for catching prey on land; and a small gill slit that, in more derived animals, became an ear.[8] The discoverers said that in all likelihood, Tiktaalik flexed its proto-limbs primarily on the floor of streams and may have pulled itself onto the shore for brief periods.[9] Specimens found thus far range from 4 to 9 feet (1.2 to 2.75 meters) in length.
See also
- Eusthenopteron, another Devonian lobe-finned fish.
References
- ^ a b Edward B. Daeschler, Neil H. Shubin and Farish A. Jenkins, Jr (6 April 2006). "A Devonian tetrapod-like fish and the evolution of the tetrapod body plan". Nature. 440: 757–763. doi:10.1038/nature04639.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ John Noble Wilford, The New York Times, Scientists Call Fish Fossil the Missing Link, Apr. 5, 2006.
- ^ a b Holmes, Bob (5 April 2006). "First fossil of fish that crawled onto land discovered". Retrieved 2006-04-07.
{{cite news}}: Unknown parameter|org=ignored (help) - ^ Nunavut Living Dictionary. Entry for tiktaalik
- ^ a b Spotts, Peter (April 6, 2006). "Fossil fills gap in move from sea to land". Retrieved 2006-04-05.
{{cite news}}: Unknown parameter|org=ignored (help) - ^ Gorner, Peter (April 5, 2006). "Fossil could be fish-to-land link". Chicago Tribune. Retrieved 2006-04-05.
- ^ a b Peterson, Britt (April 5, 2006). "An Evolutionary Finding". Retrieved 2006-04-05.
{{cite news}}: Unknown parameter|org=ignored (help) - ^ "The fish that crawled out of the water". Nature. Retrieved 2006-04-06.
- ^ Neil H. Shubin, Edward B. Daeschler and Farish A. Jenkins, Jr (6 April 2006). "The pectoral fin of Tiktaalik roseae and the origin of the tetrapod limb". Nature. 440: 764–771. doi:10.1038/nature04637.
{{cite journal}}: CS1 maint: multiple names: authors list (link)
External links
- University of Chicago website dedicated to the discovery
- Associated Press, Fossil shows how fish made the leap to land, Apr. 5, 2006.
- Alok Jha, The Guardian, Discovered: the missing link that solves a mystery of evolution, Apr. 6, 2006.
- BBC news, Arctic fossils mark move to land, Apr. 5, 2006.
- NewsHour, Fossil Discovery, April 6, 2006. (Interview with one of the discoverers)