Walking Fish reveals new evolutionary links

Scientists for the first time described features in the underside of the skull of Tiktaalik roseae, the so-called "walking fish" discovered in the Canadian Arctic in 2004. It is considered an important transitional animal in the evolution of fish into amphibians, the first land-dwelling vertebrates.

The findings showed that the migration from water to land was more complicated than merely having a fish's fins transform into legs, the scientists wrote in the journal Nature.

The head showed changes from more primitive fish that helped adapt to the new feeding and breathing conditions presented by a terrestrial environment, the scientists said. Like some other fish of its time, it had gills and lungs.

"It's not to say that Tiktaalik itself is a terrestrial animal. It spent most of its time in water, for sure," Jason Downs of the Academy of Natural Sciences in Philadelphia, one of the researchers, said in a telephone interview.

"So what it's really demonstrating is that many of these changes that are occurring and things that we once associated with terrestrial life are turning out, in fact, to be adaptations for life in shallow water settings that Tiktaalik might had found himself in," Downs added.