Alethopteris is a prehistoric plant genus of fossil pteridospermatophytes (seed ferns) that developed in the Pennsylvanian (around ). thumb|left|Alethopteris florentina De Stefani, 1901, Natural History Museum University of Pisa thumb|Alethopteris, at the State Museum of Pennsylvania in Harrisburg.|left thumb|Alethopteris sp.
Alethopteris is a prehistoric plant genus of fossil pteridospermatophytes (seed ferns) that developed in the Pennsylvanian (around ). thumb|left|Alethopteris florentina De Stefani, 1901, Natural History Museum University of Pisa thumb|Alethopteris, at the State Museum of Pennsylvania in Harrisburg.|left thumb|Alethopteris sp.
thumb|Alethopteris Serlii on mudstone|laminated mudstone from [[St. Clair, Pennsylvania.]]
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).