Tiktaalik Roseae: Missing Link "Fishapod"Biology
A fossil unearthed from 2004 to 2006 has features of both fish and tetrapods, and has consequently been dubbed a "fishapod." Tiktaalik roseae was named from the suggestion of Inuit elders in Nunavut, the cold Canadian territory in closest proximity to Greenland, where the fossil was found. The name means "large freshwater fish," and this appears to be the only thing about the fossil which isn't controversial. Ellesmere Island was the specific location of the fossil, which when viewed from a map is the island directly west of Greenland. The fossil has touched off a heated debate between scientists with various beliefs of the earth's origin. Many websites with posted articles of the fishapod have a definitive agenda behind the articles, so be careful to watch for biased or slanted information.
The skeletal structure of the fish suggests that it spent much of its time near the shoreline using its front arm-like appendages to prop itself up at the water's edge. Because the fossil is remarkably well preserved, scientists have been able to observe several unique features that true fish do not share. The front fins had wrist-like rotational ability, hence the ability to push itself onto the shore to a small degree. Additionally, Tiktaalik had a neck, which is an unusual feature. Its skull was definitely separate from the rest of its body. The structure of the gills also indicates that the creature had at least some ability to breathe oxygen like a true tetrapod. Artists' concept drawings of the fish make it look vaguely like an alligator with fins, especially with the creature peeking out of the water in typical alligator fashion.
Information about Tiktaalik can result in an exercise in vocabulary. Tiktaalik is actually an elpistostegid, which means that it is considered a lobe-finned fish from the late Devonian period. Clearly, "fishapod" proved a more concise and popular term. Tiktaalik was not found by accident. An excavation team led by Neil Shubin, Ted Daeschler, and Farish Jenkins were led to the site of Ellesmere Island by an analysis of the age of sedimentary formations in various parts of North America. The Fram Formation, where Tiktaalik was found, required the analysis of palynomorphs in the sedimentary layers. Palynomorphs are tiny particles composed of organic material, and their presence helps to determine the age of various sediments. This particular formation was determined to have been laid down in the Frasnian Age, which equates to 385 to 375 million years ago. Scientists had hypothesized that a creature like Tiktaalik would exist at this point in the fossil record, and the discovery of the creature further reinforces the validity of the analysis. Interestingly, evidence has shown that Tiktaalik was late in the evolutionary cycle, as a number of elpistostegids were known to have evolved as early as 400 million years ago.