A large, morphologically heterogeneous population of acanthomorphic acritarchs from the early Neoproterozoic Wynniatt Formation, Victoria Island, northwestern Canada, is ascribed to two form-genera, Tappania and Germinosphaera, but just a single natural taxon, Tappania. Analysis of Tappania morphology shows it to have been an actively growing, benthic, multicellular organism capable of substantial differentiation. Most notably, its septate, branching, filamentous processes were capable of secondary fusion, a synapomorphy of the “higher fungi.” Combined with phylogenetic, taphonomic and functional morphologic evidence, such “hyphal fusion” identifies Tappania reliably, if not conclusively, as a fungus, probably a sister group to the “higher fungi,” but more derived than the zygomycetes.

The presence of Tappania in the Mesoproterozoic Roper Group of Australia extends the record of putative fungi to 1430 Ma. Along with other Proterozoic acritarchs exhibiting fungus-like characteristics (e.g., Trachyhystrichosphaera, Shuiyousphaeridium, Dictyosphaera, Foliomorpha), there is a case to be made for an extended and relatively diverse record of Proterozoic fungi.

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