Fish fossil offers clues to evolution

PHILADELPHIA, Oct. 15 (UPI) -- U.S. researchers say a new look at the skull of a 375-million-year-old fish fossil provides clues to the evolutionary process.

The Academy of Natural Sciences said the study of the Tiktaalik roseae suggests the transition from aquatic to terrestrial lifestyles involved changes to the internal head skeleton, as well as appendages.

The findings are published in the Oct. 16 issue of the journal Nature.

The Tiktaalik roseae was found in 2004 above the Arctic Circle on Canada's Ellesmere Island. The creature had fish-like features such as a primitive jaw, fins and scales, as well as a skull, neck, ribs and parts of the limbs similar to four-legged animals, researchers said.

"The braincase, palate and gill arches of Tiktaalik help reveal the pattern of evolutionary change in this part of the skeleton," lead author Jason Downs said in a release. "We see that cranial features once associated with land-living animals were first adaptations for life in shallow water."