Pragian Epoch

What happened during this time?

Rhynie Chert

• The exquisitely preserved Rhynie Chert dating to 407 Ma

  • Environment fossilized amazing details from Early Devonian geyser-adjacent environment

  • The chert was formed when silica-rich water from volcanic springs rose rapidly and petrified the early terrestrial ecosystem, in situ and almost instantaneously

Plants

• Sporophytes of horneophytes, aglaophytes, rhyniophytes, zosterophylls, Asteroxylon

• Gametophytes of horneophytes, aglaophytes, rhyniophytes, zosterophylls

Cyanobacteria & Green algae

•  A charophyte Palaeonitella † is found in association with Lyonophyton, indicating that these gametophytes may have lived in semi-submerged environments

Lichens

• Winfrenatia is the oldest known terrestrial lichen

  • It comprises a thallus, made of layered, aseptate hyphae, with a number of depressions on its top surface. 

  • Each depression contains a net of hyphae holding a sheathed cyanobacterium. 

  • The fungus appears to be related to the Zygomycetes, and the photosynthetic partner of photobiont resembles the coccoid cyanobacteria Gloeocapsa and Chroococcidiopsis. 

  • There may be two separate algae, making the lichen a symbiosis of three organisms.

Fungi

• Some of the earliest evidence of mycorrhizae fungi in Earth's history.

• Vescicular Arbuscular Mycorrhizae (VAM) found in the rhizome of Aglaophyton major

• Glomerocyetes and possible ascomycetes found at locality

• Rhizophydites matryoshkae, a chytrid, was found on the in situ spores on Horneophyton lignieri (Krings et al 2021)

• Potteromyces asteroxylicola appears to be an ascomycete that colonized the aerial axes and leaf-like appendages of Asteroxylon mackiei 

  • The fungus is represented by a stroma-like structure and by conidiophores originating in tufts from beneath the cuticle, which caused a reaction in the plant that gave rise to dome-shaped surface projections

  • This suite of features in the fungus together with the plant reaction tissues provides the earliest unequivocal fossil evidence of a plant pathogenic fungus

Nematophytes

• organisms of unknown plant or fungal origin

Invertebrates

• Tydeid mites, trigonotarbid "spiders", harvestmen, myriapods, springtails, water fleas, fairy shrimp

• Freshwater crustacean Lepidocaris † is also found in association with Lyonophyton.

• Coprolites indicate that invertebrates were feeding on spores