summary The fossil record is a long‐neglected source of valuable information concerning the diversity, structure, evolution and activities of ancient fungi. However, interest in these organisms has increased in recent years as their importance in a wide variety of interactions with plants, animals and the geological environment has been recognized. Evidence from the fossil record now implicates fungi in such processes as the establishment of terrestrial plants, degradation of lignin in Devonian forests, parasitic relationships with plants and animals, and the development of ancient soils. Although fossil fungi remain difficult to study, their geological record is rich and rewarding. Recent advances in the study of fungi from the Palaeozoic and early Mesozoic (exclusive of palynological research) are presented in this review.

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An extensive fungal infection is present in silicified specimens of Callixylon newberryi (Dawson) Elkins and Wieland from the Upper Devonian of Indiana. Fungi are represented by branched, septate filaments with both terminal and intercalary chlamydospores. Clamp connections were not observed. Tracheids of the secondary xylem, decayed in varying degrees, show erosion troughs, cavities, and extensive lysis of tracheid walls. The pattern of decay is most similar to modem-day white rots, which are typically caused by basidiomycetes, while hyphal features are characteristic of either ascomycetes or basidiomycetes. The presence of wood decay coupled with a septate mycelium suggests the presence of higher fungi in the Devonian and indicates a more diverse Devonian mycoflora than has previously been recognized.

An extensive fungal infection is present in silicified specimens of Callixylon newberryi (Dawson) Elkins and Wieland from the Upper Devonian of Indiana. Fungi are represented by branched, septate filaments with both terminal and intercalary chlamydospores. Clamp connections were not observed. Tracheids of the secondary xylem, decayed in varying degrees, show erosion troughs, cavities, and extensive lysis of tracheid walls. The pattern of decay is most similar to modem-day white rots, which are typically caused by basidiomycetes, while hyphal features are characteristic of either ascomycetes or basidiomycetes. The presence of wood decay coupled with a septate mycelium suggests the presence of higher fungi in the Devonian and indicates a more diverse Devonian mycoflora than has previously been recognized.

Permineralized lycopsid megagametophytes and embryos from Upper Carboniferous strata (Westphalian A) at Burnley, England have been found within isolated megaspores assignable to Setosisporites. The specimens illustrate for the first time the reproductive biology and embryogeny of a free-sporing, bisporangiate, Paleozoic lycopod, and permit reinterpretation of the megagametophyte of Bothrodendrostrobus. Megagametophyte development is entirely endosporal. Embryogeny is comparable to that of the extant genus Isoetes, and is fundamentally different from that of the fossil lycopsid, Lepidocarpon-Lepidophloios. This further illustrates the diversity among Paleozoic lycopods and helps to clarify relationships among both fossil and extant lycopsid taxa.