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Biotic interactions in an exceptionally well preserved osmundaceous fern rhizome from the Early Jurassic of Sweden

McLoughlin, Stephen, Bomfleur, Benjamin
Palaeogeography, palaeoclimatology, palaeoecology 2016 v.464 pp. 86-96
Sarcoptiformes, adventitious roots, biocenosis, calcite, detritivores, detritus, ecosystems, epiphytes, evolution, ferns and fern allies, fungal spores, fungi, fungivores, herbivores, host plants, parasites, parasitism, petioles, rhizomes, understory, Sweden
A remarkably well permineralized osmundaceous rhizome from the Early Jurassic of southern Sweden yields evidence of an array of interactions with other organisms in its immediate environment. These include epiphytism by a herbaceous heterosporous lycopsid; putative oribatid mite herbivory and detritivory (petiole and detritus borings and coprolites); potential pathogenic, saprotrophic or mycorrhizal interactions between fungi and the host plant and its epiphytes; parasitism or saprotrophy by putative peronosporomycetes; and opportunistic or passive mycophagy by oribatid mites evidenced by fungal spores in coprolites. A combination of abrupt burial by lahar deposits and exceedingly rapid permineralization by precipitation of calcite from hydrothermal brines facilitated the exquisite preservation of the rhizome and its component community of epiphytes, herbivores, saprotrophs and parasites. Ancient ferns with a rhizome cloaked by a thick mantle of persistent leaf bases and adventitious roots have a high potential for preserving macro-epiphytes and associated micro-organisms, and are especially promising targets for understanding the evolution of biotic interactions in forest understorey ecosystems.