Filet O' Family Tree

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Quirky "Fishapod" Crawls onto Our Family Tree

from Los Angeles Times / Philadelphia Inquirer

U.S. researchers say they have found the missing evolutionary link between fish and land animals: fossils of a strange creature that crawled onto the shore about 375 million years ago.

The fossils, found on Ellesmere Island in Arctic Canada, have the skull, neck, ribs and limb bones of four-legged animals and the primitive jaw, fin and scales of fish, according to a report published today in the journal Nature.

"This really is what our ancestors looked like when they began to leave the water," according to an editorial accompanying the report.

The newly discovered species, Tiktaalik roseae [pdf graphic], "blurs the boundary between fish and land-living animal both in terms of its anatomy and its way of life," said biologist Neil Shubin of the University of Chicago, one of the co-leaders of the expedition.

"This animal is both fish and tetrapod," Shubin said. "We jokingly call it a fishapod."

The creature lived in shallow waterways, where it hunted for prey with its mammal-like snout and sharp teeth, but it was able to pull itself out of the water for short periods and move around on its limblike fins, the researchers say.

The fossils, ranging in length from 4 to 9 feet, were remarkably well-preserved, allowing the team to examine the joints carefully and to conclude that the shoulder, elbow and wrist joints were sufficiently strong to support the animal's body on land.

"Human comprehension of the history of life on Earth is taking a major leap forward," said H. Richard Lane of the National Science Foundation, which paid for the research along with the National Geographic Society and others.

"These exciting discoveries are providing fossil Rosetta stones for a deeper understanding of this evolutionary milestone: fish to land-roving tetrapods," or four-legged creatures, he said.

In a separate opinion piece in Nature, scientists not involved with the research gushed that the fossil "might in time become as much of an evolutionary icon as...Archaeopteryx" - the famous reptilian ancestor of modern birds.