Sagenopteris trapialensis are leaves of extinct species of seed fern from Chubut, Patagonia Argentina.

[1] At the moment, S. trapialensis is based on impression fossils found in the Early Jurassic Lonco Trapial Formation near Paso del Sapo, Chubut Province.

Sagenopteris trapialensis comprises palmately arranged leaves with 4 ovate to obovate leaflets with anastomosing venation.

The central leaflets are almost symmetrical, whereas the lateral ones are markedly asymmetrical.

Leaves of various sizes and forms were found, ranging from less than 5 mm.