What did Earth look like in the Devonian? (419.62–358.86 Ma)

Key events of this period

• The puzzle of early insects

  410 Ma

  Rhyniognatha from the roughly 410–407-million-year-old Rhynie chert was once presented as the oldest insect. Re-examination of its mouthparts suggested it may instead be a centipede, and its identity remains debated. This fossil cannot securely date either insect origins or the start of insect flight.

  References: Haug and Haug: The presumed oldest flying insect: more likely a myriapod? · Schachat et al.: Illusion of flight? Absence, evidence and the age of winged insects

• Early forests reshape rivers

  390 Ma

  Around 390 million years ago, Calamophyton trees just 2–4 metres tall grew beside river channels in today’s southwest England. Roots held sediment and shed branches littered the ground, helping reshape riverbanks. This is among the oldest known forest records, not a pinpointed birthplace of all forests.

  References: Cardiff University: Earth’s earliest forest revealed in Somerset fossils

• Late Devonian Extinction

  375 Ma

  Late Devonian crises repeatedly struck marine life, devastating tropical shallow-water ecosystems built by corals and sponges. The 375-million-year marker represents this longer crisis; the relative roles of climate and changing ocean chemistry remain debated.

  References: Late Devonian Extinctions — Sam Noble Oklahoma Museum of Natural History · The expansion of land plants during the Late Devonian contributed to the marine mass extinction

• From fins toward limbs

  375 Ma

  Tiktaalik, about 375 million years old, was still a fish with fins. A 2024 CT study suggests its ribs connected to the pelvis to help support its body. The transition toward limbed vertebrates assembled features gradually; this fossil does not mark a single first step onto land.

  References: University of Chicago: How a change in the hips led to evolution of walking