Pragian Age

What happened during this time? 

Rhynie Chert

• The exquisitely preserved Rhynie Chert from Scotland, dating to 407 Ma

  • The environment at this locality fossilized exquisite details from the 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

Flora

Sporophytes of the following taxa:

• Aglaophyton major †: a paravascular plant with a rhizome and isotomous aerial branching; Lyonophyton rhyniensis † is the gametophyte of this taxon.

• Asteroxylon mackiei †: an early drepanophyte lycopod with leaf-like enations and root-bearing axes with quasi-roots.

• Horneophyton lignieri †: a paravascular plant with a corm and isotomous aerial branching; Langiophyton mackiei † is the gametophyte of this taxon.

• Nothia aphylla †: a vascular plant with rhizomes and leafless upright axes bearing lateral and terminal sporangia; Kidstonophyton discoides † is the gametophyte of this taxon.

• Rhynia gwynne-vaughanii †: a vascular plant with rhizomes and leafless upright axes bearing lateral and terminal sporangia; Remyophyton delicatum † is the gametophyte of this taxon.

• Trichopherophyton teuchansii †: a zosterophyll with rhizomes and leafless upright isotomous & pseudomonopodial axes with circinnate growth.

• Ventarura lyonii †: a zosterophyll with rhizomes and smooth upright isotomous axes with lateral sporangia

Gametophytes of the following taxa:

• Kidstonophyton discoides †: male plants with a rosette of aerial shoots with archegonia in cups; Nothia aphylla † is the sporophyte of this taxon 

• Lyonophyton rhyniensis †: female plants with an upright istomomous form; male plants with a rosette of aerial shoots with archegonia in cups; Aglaophyton major † is the sporophyte of this taxon 

• Langiophyton mackiei †: rosette of aerial shoots with archegonia in cups; Horneophyton lignieri † is the sporophyte of this taxon

• Remyophyton delicatum †:  Upright aerial unbranched axes that bear either archegonia or antheridia; Rhynia gwynne-vaughanii † is the sporophyte of this taxon 

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 reticulata † 

  • Taylor, Hass & Kerp, 1997

  • This taxon is the oldest known terrestrial lichen

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

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

  • The fungus appears to be related to the mucoromycetes, and the photosynthetic partner of the 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 mycorrhizal fungi in Earth's history.

• Vescicular arbuscular mycorrhizae (VAM) found in the rhizome of Aglaophyton major †

• Glomerocyetes and possible ascomycetes found at the locality

• Rhizophydites matryoshkae †

  • Krings et al., 2021

  • A chytrid, that was found on the in situ spores of Horneophyton lignieri †

• Potteromyces asteroxylicola † 

  • A potential 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 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

Non-Rhynie Localities

• Bryophyta: Sporogonites †; Riccardiothallus †

• Others: Amplectosporangium †, Catenalis †, Chakassiophyton †, Changwuia †, Dawsonites †, Hostinella †, Margophyton †, Minusia †, Pilophytites †, Sciadocillus †, Stachyophyton †, Wahnbachella †

• Rhyniophytes and Cooksonioids such as Celatheca †, Cooksonia †, Eogaspesia †, Hedeia †, Hsüa †, Rhynia †, Salopella †, Sartilmania †, Sciadophyton †, Sennicaulis †, Stockmansella †, Uskiella †, Yarravia †

• Zosterophylls such as Bathurstia †, Deheubarthia †, Demersatheca †, Discalis †, Distichophytum †, Gosslingia †, Guangnania †, Gumuia †, Hicklingia †, Huia †, Nothia †, Oricilla †, Ramoferis †, Sawdonia †, Taeniocrada †, Tarella †, Trichopherophyton †, Thrinkophyton †, Ventarura †, Wenshania †, Yunia †, Zosterophyllum †

• Lycopods such as Asteroxylon †, Baragwanathia †, Cervicornus †, Drepanophycus †, Estinnophyton †, Halleophyton †, Hueberia †, and Zhenglia †

• Barinophytes, including Adoketophyton †, ?Bracteophyton †, ?Dibracophyton †, Krithodeophyton †, Pectinophyton †, and Protobarinophyton †

• Basal euphyllophytes are also found in other (non-Rhynie) localities such as Psilophyton † and Polythecophyton †

  • Pauthecophyton † from Yunnan, China (Xue et al., 2012)

  • Armoricaphyton † from Montjean-sur-Loire, France (Gerrienne and Gensel, 2016)

  • Eophyllophyton †, from China, is one of the first euphyllophytes with flattened appendages that appear to be small leaves (Hao, 1988; Hao & Beck, 1993)