A fossil of the strange Tiktaalik fish has been giving up more of its secrets this week.

In a paper in Nature Jason Downs of the Academy of Natural Sciences of Philadelphia and his colleagues report on the head structure of Tiktaalik roseae, dubbed the ‘fishapod’ due to its position between fish and land-dwelling creatures. They show that it had developed features to allow it to breathe air and move on land, features such as a neck to allow head movements when the body is not as free to move as it would be in open water.

National Geographic notes that the features associated with the ‘neck’ suggest the animal wasn’t very good a pumping water into its body. This doesn’t mean it couldn’t breathe through its gills, but it suggests it maybe wasn’t spending lots of time underwater.

“It’s not to say that Tiktaalik itself is a terrestrial animal,” Downs told Reuters. “It spent most of its time in water, for sure. 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.”

“We used to think of this transition of the neck and skull as a rapid event. largely because we lacked information about the intermediate animals. Tiktaalik neatly fills this morphological gap. It lets us see many of the individual steps and resolve the relative timing of this complex transition,” says paper author Neil Shubin, of the University of Chicago and Field Museum (press release).

Image: A model of Tiktaalik roseae / Model by Tyler Keillor, Photo by Beth Rooney