Roadcuts along Pennsylvania highways have once again offered a window into the evolutionary history of vertebrates.

Professor Ted Daeschler and his colleagues provided expertise after York resident James J. Smaling found large, well-preserved fossil bones in a roadcut exposure along the westbound lanes of Route 322 in Centre County.

“Jim and his fossil-collecting buddy, the late Jim Forster, delivered about 250 pounds of red sandstone in several large blocks to the Academy’s paleontology lab, beginning the process of assessing the fossils, splitting the rocks to reveal additional fossils, and the detailed work of fossil preparation and preservation,” says Daeschler.

They quickly determined that the find belonged to the group called tristichopterids, a group of lobe-finned fish.

“While tristichopterids have a fish-like look… they’re actually disconnected from the modern concept of a fish and are more closely related to vertebrates with limbs, fingers, and toes.”

Jason Downs

Smaling’s find — which included high-quality cranial and fin material as well as body scales — is a previously unknown species within the Langlieria group. The new species Langlieria smalingi, named in honor of its discoverer, was described and published in the Proceedings of the Academy of Natural Sciences of Philadelphia in 2022.

The new species aligns more closely to humans and other limbed vertebrates than to fish as we view them today, says Jason Downs, a research associate at the Academy and a co-author of the paper.

FISH_OUT_OF_WATER

York resident James J. Smaling found large, well-preserved fossil bones in a roadcut exposure in North Central Pennsylvania. The bones belonged to the group called tristichopterids, a lobe-finned fish. The new species aligns more closely to humans and other limbed vertebrates than to modern fish.

“While tristichopterids have a fish-like look — meaning they have fins, swim and breathe with gills — they’re actually disconnected from the modern concept of a fish and are more closely related to vertebrates with limbs, fingers, and toes,” Downs explains.

ROADSIDE_ATTRACTION

Tristichopterid fossils have been collected in Tioga, Lycoming, Clinton and Centre counties in Pennsylvania. “To understand the present, we have to first understand the past, so the mind needs to reconstruct Pennsylvania with muddy streams washing from east to west in a subtropical environment — really a very different place than we are familiar with,” Daeschler says. “Pennsylvania has really good rocks formed in the stream systems from that time period, and that’s what we are after.”

The tristichopterids fit into the tree of life among a great diversity of lobe-finned fish that lived in streams and along coastlines in the middle and late part of the Devonian Period. They were large, predatory fish, a meter or more in length.

Downs and Daeschler are examining the Devonian age to build a more complete understanding of advances in the transition from aquatic to terrestrial environments that occurred in that era.