Old Red Sandstone, sea

The Old Red Sandstone is known for its diverse assemblage of early Devonian fish, with many fossils discovered in Scotland, Wales, and England.

Here’s a description of some key fauna found in the Old Red Sandstone during the Early Devonian

  • Acanthodians: These were among the most common fish in the Early Devonian ORS. They were relatively small, with spines supporting their fins, and a covering of bony scales that gave them a somewhat shark-like appearance.
  • Osteostracans: These jawless fish with bony head shields are characteristic of the Devonian period. Cephalaspis, with its horseshoe-shaped head, is a well known example found in UK ORS deposits.
  • Placoderms: These heavily armored fish had jaws and bony plates covering their heads and bodies. Some species, like the giant predator Dunkleosteus, could reach enormous sizes, but smaller placoderms were also common in the ORS environments.
  • Early Lobe-Finned Fish: Found less frequently, these fish represent an important lineage, as some developed limb-like fins and became ancestral to the first terrestrial tetrapods (four-legged animals).
  • Eurypterids: These aquatic “sea scorpions” were significant predators in some ORS environments. Some grew to substantial sizes.