A Fish that could Walk on Land found by Scientists

Fossilized remains of 375-million-year-old species of ancient fish are found by the paleontologists working in the Canadian Arctic.

The team of scientists working in the Canadian Arctic has unearthed skeletons of a huge fish that could crawl across land. The discovery has filled an evolutionary gap in the passage between water and land animals.

Remains of the new species called Tiktaalik Roseae, the large, predatory fish that bears a number of features found in four-limbed creatures, were found by Neil Shubin of the University of Chicago and his colleagues Ellesmere Island, some 600 miles from the North Pole, encased in frozen rock.

Nowadays Ellesmere Island is the icy sovereignty of the polar bear, but 375 million years ago, as part of a super continent that straddled the equator, it was a subtropical delta.

It has the fins and scales just like all fish but it also has a number of distinctly un-piscine characteristics, such as crocodile-like skull, neck and robust ribs resemble those of a land animal such as a group known as tetrapods.

Neil Shubin, leader of the University of Chicago team that found the fossils said, "It is a fish that shows a surprising combination of characteristics of land-living animals," he added "This animal represents the transition from water to land--the part that includes ourselves."

Intrinsically Tiktaalik roseae clearly fills the breach between previously known tetrapod like fish such as Panderichthys, which existed some 385 million years ago, and the earliest tetrapods, Ichthyostega and Acanthostega, which lived about 365 million years ago. Shubin says, "This animal is both fish and tetrapod; we jokingly call it a ’fishapod."

In the very well-preserved specimens, especially significant is the anatomy of Tiktaalik’s pectoral fin, which contains the makings of a proper tetrapod arm. The specimens show the creature had sharp teeth, a jaw ranging from 10-20 inches across and a flattened body that could reach 3 yards in length. It is a favorable part of the spectacular 3-dimensional preservation of the bones--many of which were found still articulated--and the discovery of multiple specimens that enabled the researchers to estimate the range of motion of the fin bones.

Shubin of the University of Chicago was accompanied by Ted Daeschler, of the Academy of Natural Sciences in Philadelphia, and Farish Jenkins of Harvard University found the fossils of the animal, which the scientists estimate was as long as 9 feet (274 centimeters) and was still distinctly a fish, in a formerly boggy area that seems to have been flooded, possibly when a riverbank broke open.

The scientists have planned to return this summer to search for more recent skeletons that might show the further disappearance of fin bones as well as to try to determine why this fish found it useful to leave the water.