May
01
2006

Fish or land animal? Tiktaalik is some of each


A model and a fossil show how Tikaalik Roseae might have lived in shallow stream beds about 375 million years ago.

What lived in water, could do push ups and might be the missing link in the evolution of sea creatures and land animals?

It’s Tiktaalik roseae, a crocodile-like creature that lived most of the time in the water, but ventured on land occasionally. Fossil remains of the large, nearly 400-million-year-old creature were recently found north of the Arctic Circle in Canada.

It’s the first solid fossil evidence that shows the transformation of aquatic animals into being land creatures. Tiktaalik specimens that were found range in length from four to nine feet long and look like a cross between a fish and a crocodile. They swam in shallow streams in what at the time, around 375 million years ago, was believed to be a subtropical climate. Tiktaalik were meat eaters.

The key that makes researchers believe it went up onto land is that Tiktaalik’s front fins had a bone structure that is much like a shoulder, upper arm, elbow, forearm and wrist. It’s believed the creatures would slither out of the water and pull themselves around on land much like seals do today.

The head structure of Tiktaalik is also a piece of evidence in the water-to-land evolution. It had a crocodile-like head, including eyes on top of the skull rather than on the side, like fish. It could also move its head independently of its shoulders like land animals can do today. But the creature’s jaws and snout were very fishlike. Researchers think it might have had both a set of lungs and gills for breathing. But like fish, it had scales and fins.

Scientists are planning to return to the Artic region to do further digging, but due to the cold climate there today, there is just a short window for doing field research. But much of what scientists are seeing in Tiktaalik confirms their guesses as to how water creatures could eventually convert to land animals.

The new findings were published in a recent edition of the journal Nature. Researchers have set up their own Tikaalik website with much more information about the discovery.

Your Comments, Thoughts, Questions, Ideas

Freddrika of Idaho's picture
Freddrika of Idaho says:

Why do the shapes of the skull and fins look so different in the model. Please give a scientific explanation. I think it's a fish rather thena land mammal.

posted on Thu, 03/15/2007 - 7:27am
mdr's picture
mdr says:

I think what you're seeing in the photograph are differences of perspective rather than shape. The skull and skeleton are viewed more from above, while the model is viewed more from the side.

posted on Thu, 03/15/2007 - 12:01pm
Anonymous's picture
Anonymous says:

There are still fish today that can walk on land( well, not walk, but hop), so what makes this the proof of the move from water to land? I can't believe that these scientists are taking all this garbage in and taking it seriously.

posted on Sat, 01/12/2008 - 11:57pm
Gene's picture
Gene says:

Scientists studying the skull have found it, too, contains adaptations for life on land.

posted on Tue, 10/28/2008 - 3:25pm

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