Early Devonian

What happened during this time?

• The Early Devonian flora shows a mix of early forms and more derived architectures: Rhyniophytes, Cooksonioids, Zosterophyllophytes, Trimerophytes, Lycopods, as well as the first appearance of the Cladoxylopsids.

• The exquisitely preserved Rhynie Chert from the Pragian Epoch provides insights on the ecosystem of the Early Devonian

• Earliest evidence of rooted paleosols (fossil soils) in Asia from Early Devonian deposits of Yunnan, China (Xue et al. 2016)

• Land plants getting larger, but most are thought to be restricted to the water's edge and moist, lowland habitats

  • Although a fossilized dryland river system from Yunnan, South China, shows evidence of K- or H-shaped branching structures that are morphometrically comparable to the rhizomes of zosterophylls and early lycopsids (Xue et al. 2023) 

  • These plant-bearing paleosols provide direct evidence for the development of primitive vegetation on drylands. and could have been a significant component of the Early Devonian landscapes, controlling the retention of both mobile elements (Ca and Mg) and fine-grained sediment on land, and mantling and protecting buried soil carbon against erosion.

• Drepanophycalean lycopsids

  • Long-lived, below-ground rhizomes producing large clones that helped the plants survive frequent sediment burial in well-drained soils within a seasonal wet-dry climate zone

  • Rhizome networks contributed to the accumulation and soil formation (pedogenesis) of floodplain sediments and increased the soil stabilizing effects of early plants

  • Sengelia radicans (Wyoming) provides a whole plant reconstruction due to preservation (Matsunaga and Tomescu 2017)

• Heterospory originates by approximately 407 Ma (Traverse 1988)

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

  • Omniastrobus dawsonii from the Early Emsian shows a gradation of small to large spores.

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

  • Franhueberia, an axis exhibiting secondary xylem, is found in the mid-late Emsian (Hoffman and Tomescu 2013)

  • This is the oldest evidence of wood production in the fossil record

• Full list of Early Devonian plants