Philadelphia paleontologist Ted Daeschler is best known for his research team's discovery of the Tiktaalik roseae in 2004.  The fossil of the ancient fish is considered the best evolutionary link between fish and limbed land animals.

Daeschler has just discovered another species from the same fossil field on Ellesmere Island, off the coast of Canada in the Arctic circle. The new species is called Holoptychius bergmanni.

"It's a predatory fish, probably 3 or 4 feet in length," Daeschler said. "It had some heavy scales, big teeth. It was one of the predators in the aquatic ecosystems that were around 380 million years ago."

Daeschler's team has spent parts of five field seasons at the same location, collecting animal and plant fossils from the Devonian period.

"Just like you might reconstruct an ecosystem today based on the variety of animals that live there," Daeschler said, "we're interested in reconstructing the ecosystems of the past, based on the variety of animals that lived there."

Daeschler and his team are carefully reconstructing this ecosystem to figure out what environmental circumstances led early fish to begin evolving into limbed land animals.

So far, they have named three fish from the fossil field, including Tiktaalik and Holopytchius. Daeschler said there are fossils of many more creatures waiting to be studied at the Academy of Natural Sciences in Philadelphia.

The new species was described in the latest issue of the Proceedings of the Academy of Natural Sciences of Philadelphia, along with a second new fish discovered by Daeschler.

He found that species,  an armored fish named Phyllolepis thomsoni, in the sandstone deposits that construction workers were cutting through to create a new road in central Pennsylvania.

"One of the ways that we find fossils here in Pennsylvania, because there's not that much natural rock exposure, we work along the sides of highways," Daeschler said. "When they cut through to make these road cuts, they kind of open up a window into the Devonian period."

The fish's bones were destroyed when Daeschler tried to get the fossil out of the rock formation.

He was able to create a skeletal model by painting latex into the negative space left as rock formed around the fish skeleton.