Emsian Stage

What happened during this time?

Many vascular and non-vascular plants on the landscape, but terrestrial landscapes are still considered primitive (Hotton et al. 2001)

• Nematophytes such as Spongiophyton and Prototaxites

• Bryophytes such as Sporogonites

• Rhyniophytes, Cooksonia, and early Tracheophytes such as Aarabia, Amplectosporangium, Aphyllopteris, Bitelaria, Changwuia, Chakassiophyton, Dawsonites, Eogaspesia, Hostinella, Hsüa, Huia, Huvenia, Margophyton, Minusia, Pectinophyton, Psilophytites, Renalia, Stockmansella, Rhabdophyton, Taeniocrada, Sciadocillus, Sciadophyton, Thursophyton, Uskiella, and Yarravia 

  • Plants like Huvenia and Sciadophyton occupy are farther away from the channel margins 

• Zosterophyllophytes such as Crenaticaulis, Danziella, Distichophytum, Estinnophyton?, Forgesia, Guangnania, Hicklingia, Oricilla, Sawdonia, Zosterophyllum

  • These plants occupy low-energy, water-saturated habitats such as marshes and back swamps (Hotton et al. 2001), which are stressful and low in dissolved oxygen

  • Plants had adaptations to this stressful environment, such as resistant cuticle, growth after producing spores, and numerous buds for regrowth

• Lycopods such as Baragwanathia, Cyclostigma, Drepanophycus, Kaulangiophyton, and Leclercqia

• Barinophytes such as Bracteophyton, Krithodeophyton, and Omniastrobus

• Early euphyllophytes such as Chaleuria, Oocampsa, Psilophyton, Trimerophyton and Wilhowia were all present

  • Most of these plants occupy higher-energy, ephemeral habitats such as cross-bar channels in rivers (Hotton et al. 2001), although Psilophyton forbesii  existed in back swamp conditions

  • These plants lived in high-disturbance environments with high reproductive output and short life spans

  • Psilophyton diakanthon is an Emsian species that possess fibers in the inner cortex and enations / prickles which are the earliest possible evidence of anti-herbivore defense

  • Foozia, a possible early Cladoxylopsid is also found at this time

  • In addition, Pertica was probably the tallest plant around at this time, although woody growth in Franheuberia may have allowed for tall growth

  • Franhueberia (Hoffman and Tomescu 2013), Gmujij tetraxylopteroides (Pfeiler & Tomescu 2020)  and Armoricaphyton (Strullu-Derrien et al. 2014) axes exhibiting secondary xylem are found in the mid-late Emsian 

    • These are the oldest evidence of wood production in the fossil record

• Heterospory originates by approximately 407 Ma (Traverse 1988)

  • Isolated mega- and micro-spores are the oldest evidence in the fossil record 

  • Omniastrobus dawsonii, a lycophyte from the Early Emsian, shows a gradation of small to large spores, with median-sized spores, as well.

  • Chaleuria, a euphyllophyte found in the Emsian, also shows heterospory with sporangia that exhibit small, large, or mixed spores.