Here is a geological time-line illustrating key events during fungal evolution, including structural and period data. Just click on an Era to find out more information.
Proterozoic. (670 - 2500 millions of years ago)
During this Eon, prokaryotes were abundant (Oldest prokaryote fossils are from around 3500 mya - millions of years ago). Fossil evidence for eukaryotic organisms (presumably protists) dates back to about 2000mya. Atmospheric oxygen levels were around 0.2%. Only marine life at this time. Here, the last common ancestor of plants, animals and fungi existed around 1000 mya, plants then diverge first. Animals and fungi lineages shared a more recent common ancestor than plants, a colonial flagellate, where animals and fungi diverged around 965 mya. Green algae, red algae, diverse single-celled organisms and wormlike fossils mark the end of the Proterozoic.
This period marks the start of the Phanerozoic Eon and the Paleozoic Era. The oldest known metazoans date back to this time, including annelids and arthropods. Marine life included various faunas. Some fossils understood to be of lichen origin. It is within this era (600 mya) that estimates of certain phylogenetic splits have been made from studies based on ribosomal DNA sequences. The origin of land plants has been conservatively placed here, as has the most derived fungal (Ascomycota-Basidiomycota) lineage divergence. The existence of a linage of Glomales has also been estimated in this period (Diverging from the Ascomycota and Basidiomycota around 600 mya).
The fossil record from the Cambrian period indicates nearly all major groups of invertebrate animals and the first vertebrates, the jawless fish named ostracoderms, were present. Atmospheric oxygen levels reach near 2%. The end of the Cambrian period is marked by several extinction events, with the loss of previously abundant trilobites, brachiopods, molluscs and echinoderms to name but a few. Terrestrial fungi diverge from chytrids around 550 mya.
Major extinction of many surviving invertebrates and planktonic protists from the Cambrian period occurred in the Ordovician seas. Evidence of early terrestrial life comes from fossil microarthropods, spore tetrads and plant cuticle, indicating terrestrial plants. Mycorrhizas evident in plant fossils 460 mya, the fungus being a member of the Glomales (Phylum Zygomycota), a group in which all extant taxa are arbuscular mycorrhizal (AM) fungi. Adds weight to the hypothesis of a early symbiotic origin of terrestrial plants. Possible millipede trace fossils have been found dating from the latter part of this period.
Possible terrestrial filamentous fungal fossils, providing evidence for Ascomycota, found in Sweden from this period. Definitive evidence that animals and plants invade land. A general increase in plant fossils from terrestrial environments of this period including charophytes and tracheophytes. Millipedes, centipedes and first insects common as well as ostracoderms (the first jawed fish). Extensive barrier reefs were formed and the atmospheric oxygen levels were leveling out to around 20%.
Definitive evidence of mycorrhiza fungi from their association with the Rhynie Chert flora in Scotland, 400 mya. Diversity of Chytridiomycota also revealed from this flora. Ascomycetes separate from Basidiomycetes. Diversification of land plants increase resulting in evolution of potential fungus associates, including the lycophytes and rhyniophytes. The presence of the first amphibians and all major groups of fish. Many groups of wingless insects were present in this period, as well as mites, scorpions and spiders. The continents all move towards each other, and major extinction of reef-building animals.
Evidence of high fungal diversity in this period due to the reports of clamp connections (thus showing that Basidiomycetes had maybe evolved by this period), zygospores, enclosed fruiting structures and variation of dispersed spores. Widespread forests of primitive plants form coal deposits (coal-forming swamps common). New insects such as cockroaches, May flies and dragonflies are on the scene. Towards the end of this period, the first reptiles appear and amphibians become more diverse.
Definitive evidence of Basidiomycete clamp connections. Seed plants including conifers become more common. During this period the land masses form a single continent. A great extinction event occurred at the end of the Permian bringing a massive decrease in the number of organisms in both marine and terrestrial domains. Around 80% of marine life became extinct and out of the 21 insect forms known to be living in the Permian, only 13 orders survived. The effect of the extinction effect on fungi is presently not known.
This period marks the end of the Paleozoic Era, and the beginning of the Mesozoic Era. This is the period where the first dinosaurs could be seen. Gymnosperms (cycads) and ferns were common plants. The repopulation of the seas was beginning by the extinction survivors. The continents began to move apart. Few plant fossil regions exist from this time in which the plants are fossilised in such a way to provide fungal fossils. The few that do indicate a wide diversity of fungi.
Giant dinosaurs are plentiful, the first birds and mammals are seen. Seedless vascular plants are common. Most modern insects including moths, beetles, grasshoppers and termites are abundant. Fungal spores found in amber (225 mya). Basidiomycete radiation occurs, poroid and agaricoid forms evident.
Further fragmentation of various land masses, including South America, Africa and Australia parting. Massive extinction of large animals, including dinosaurs and marine reptiles, maybe due to meteor and subsequent climate change. Divergence of placental and marsupial mammals. Gilled mushrooms found (90 mya) strongly resembling current species. Rust fungi make their first appearances.
The Mesozoic Era ends and the Cenozoic Era begins. Throughout this era, fossil fungi are remarkably like those of present day species, indicating fungi have had a long, stable history. Fruiting bodies of shelf fungi, mushrooms and puffballs all make their first appearance in the fossil records. Diversification of birds, mammals and flowering plants was still continuing and the genus Homo appears roughly around 1.6 million years ago.
