Silurian fungal remains: probable records of the Class Ascomycetes

Among the abundant plant microfossils obtained from the late Silurian Burgsvik Sandstone are spores and filaments whose morphology suggests a fungal origin. These include large multiseptate spores resembling conidia of present-day Fungi Imperfecti; ovate, reniform, rugulately ornamented unicellular spores; branched filaments with perforate septa; and filaments with flask-shaped appendages resembling phialides. We suggest that these microfossils represent the remains of the imperfect stages of terrestrial Ascomycetes, and provide evidence for an origin of this group at least contemporaneous with the earliest land plants. Larger, ovoid and cylindrical heterogeneous bodies composed of hyphal fragments resemble the fecal pellets of mycophagous microarthropods. The implications of these in terms of early terrestrial ecosystems are discussed.