Keywords: Psaronius petiole scars.png en Psaronius stem surface petiole base confi gurations A Caulopteris B Megaphyton C Hagiophyton D Artisophyton 2014-06-26 12 11 33 Pfefferkorn H W 1976 Pennsylvanian tree fern compressions Caulopteris Megaphyton and Artisophyton Pfefferkorn H W U S Geological Survey PD-USGov Uploaded with UploadWizard Psaronius |