The imprints were found in reddish- brown, fine-grained sandstone of the Mauch Chunk Formation in eastern Pennsylvania. The rocks were collected decades ago but had been sitting, unexamined, in the Reading Public Museum Collection in that state. They were rediscovered by college student David Fillmore as part of his senior thesis at Kutztown State University, also in Pennsylvania
[Another story about the same fossils but with more details.
Experts discover rare amphibian imprints]
Right here in PA folks. Of course today you can just go to the Susquehanna River and get yourself a live Hellbender.