Glossopteris
Glossopteris is probably the most familiar fossil leaf to non-paleobotanists. The name Glossopteris is Latinized from two Greek words meaning “tongue-fern”, referring to the elongated shape of individual leaves. Glossopteris was not a true fern - it was a seed fern (a group of primitive gymnosperms) (Plantae, Pteridospermophyta, Glossopteridopsida, Glossopteridales, Glossopteridaceae). Glossopteris is reconstructed as a large deciduous tree.
The Australian rock shown below is a commercial fossil specimen with several hematite-stained leaf impressions of Glossopteris browniana Brongniart, 1831 (or Glossopteris indica Schimper, 1874 - I’m not sure which one this is). Glossopteris species taxonomy is notoriously convoluted, with >200 nominal species described worldwide. During the Permian, Glossopteris-dominated forests covered much of the ancient continent of Gondwana (= South America + Africa + Arabia + Antarctica + Madagascar + India + Australia).
Glossopteris has tremendous significance in the history of geology. The modern-day geographic distribution pattern of Glossopteris fossils was a key piece of paleontological evidence that Alfred Wegener used in formulating his Continental Drift Hypothesis in 1915.
Stratigraphy: Illawarra Coal Measures, mid-Kazanian or Midian/Tatarian or Dzhulfian Stage, Upper Permian.
Locality: Dunedoo, Sydney Basin, eastern New South Wales, southeastern Australia.
Glossopteris leaves in hard deltaic claystone (field of view 12.4 cm across) from the Upper Permian of Dunedoo, New South Wales, Australia.
Wegener, A. 1915. Die Entstehung der Kontinente und Ozeane. Braunschweig. F. Vieweg. 94 pp. [English translation of 4th edition, 1966: The Origin of Continents and Oceans. 246 pp.]