Tiktaalik: Meaning (information, definition, explanation, facts)

Tiktaalik (IPA pronunciation: [tikta:lik]) is a genus of extinct sarcopterygian (lobe-finned) fishes from the late Devonian with many tetrapod-like features. <ref name=Nature></ref> It lived in the late Devonian period, 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 twenty million years later. Its mixture of fish and tetrapod characteristics led its discoverers to characterize Tiktaalik as a "fishapod". <ref>John Noble Wilford, The New York Times, Scientists Call Fish Fossil the Missing Link, Apr. 5, 2006.</ref>

Although Tiktaalik is accepted as a "missing link"—indeed, as a classic transitional form on a par with Archaeopteryx—it still shows pronouncedly fishlike characteristics. Most notably, its limbs lack the fingers and toes that mark true tetrapods. Shubin is planning to revisit Ellesmere Island, the site of the discovery, to search for fossils which more closely capture the time when vertebrates colonized dry land. <ref name="Holmes"></ref>

The name Tiktaalik is an Inuktitut word meaning "burbot", a shallow-water fish. <ref name=ILD>Nunavut Living Dictionary. Entry for tiktaalik</ref> The "fishapod" genus received this name after a suggestion by Inuit elders of Canada's Nunavut Territory, where the fossil was discovered. <ref name=CSM></ref>

Discovery

The three fossilized Tiktaalik skeletons were discovered in frozen river sediments on Ellesmere Island, Nunavut, in northern Canada<ref></ref>. At the time of the species' existence, Ellesmere Island was part of the Laurentia continent<ref name=CSM/>, which was centered on the equator and had a warm climate. Neil Shubin and Ted Daeschler, the leaders of the team, have been searching Ellesmere Island for fossils since 1999<ref name="Peterson"></ref>.

The remarkable find was made by a paleontologist who noticed the skull sticking out of a cliff wall. On further inspection, the ancient animal was found to be in fantastic shape for a 383-million-year-old specimen. <ref name="Peterson"/>

The discovery was published in the April 6 2006 issue of Nature <ref name=Nature/> 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." <ref name=Holmes/>

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.<ref></ref> The discoverers said that in all likelihood, Tiktaalik flexed its proto-limbs primarily on the floor of streams and may have pulled itself on to the shore for brief periods.<ref></ref> Specimens found thus far range from 4 to 9 feet (1.2 to 2.75 meters) in length.

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