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Devonian · 419.2 – 358.9 Ma

Devonian fossil sites

The Devonian is called the 'Age of Fishes' for the explosive radiation of placoderm and lobe-finned fishes, including the lobe-fins that gave rise to the first tetrapods. Devonian sites span Morocco's Anti-Atlas, the Gogo Formation in Western Australia, and the Old Red Sandstone of Britain.

The armoured skull and shearing jaw plates of the placoderm fish Dunkleosteus terrelli
Photo: James St. John, CC BY 2.0, via Wikimedia Commons

The Devonian carries the name Age of Fishes for good reason. Armored placoderms, early sharks, and lobe-finned fish filled the seas. One lineage of those lobe-fins walked onto land before the period ended. Forests appeared at the same time, and the first trees changed weathering and soil chemistry across whole continents.

Marine Devonian rock is the practical target for collectors. Brachiopods are abundant and varied. Trilobites reach their most ornate forms here, with long spines and large compound eyes. Phacops and Eldredgeops carry globular eyes with individual lenses still preserved, which is why collectors prize them. Corals and crinoids fill out the rest of the fauna.

Thirty entries in this guide sit in Devonian rock. Thirteen sit in Morocco, where the Anti-Atlas exposes marine rock across open desert and supplies most of the world's commercial trilobites. Nine of the thirty allow free collecting. Nine others are viewing sites, so check the access note on each page before you plan a visit.

30 fossil sites

Updated 4 August 2026

Life of the period

Three to know from the Devonian

You will not find all of these yourself. They are the animals and plants that make the period worth reading about.

  • A museum model of Dunkleosteus seen from the front, with the bony shearing plates that served as its jaws.
    Armoured placodermDunkleosteus

    It had no teeth. Instead the jaw bones formed shearing plates that sharpened themselves each time they slid past one another. Only the armoured head and shoulders fossilise, so the rest of the body is reconstruction.

    Ryan Schwark, CC0

  • A model of Tiktaalik showing its flat head, eyes set on top, and stout front fins.
    Fish with a neckTiktaalik

    Found in 2004 on Ellesmere Island after a deliberate search for rocks of the right age and setting. It has a neck, which fish do not, and shoulders that could prop it up. The prediction and the find matched.

    Bloopityboop, CC BY-SA 4.0

  • Three fossil trilobites laid in a row beside a centimetre ruler.
    Devonian trilobiteEldredgeops

    Its compound eyes hold individual calcite lenses, each one a crystal aligned so light passes through cleanly. The lenses survive fossilisation, so you can look through the same optics the animal used.

    Smithsonian National Museum of Natural History, CC0

All Devonian sites

Frequently asked questions

Why are Moroccan trilobites so common in shops?
The Anti-Atlas exposes Devonian marine rock over a very large area with almost no vegetation. Local cooperatives collect and prepare specimens commercially. Preparation quality varies, and composite or partly carved specimens do reach the market.
What is the best Devonian fossil for a beginner?
Brachiopods. They are abundant, robust, and survive weathering well. Spirifer and Mucrospirifer have distinctive wing-shaped outlines that make them easy to recognize in the field.
Where can I find Devonian trilobites in the United States?
The Silica Formation near Sylvania in northwest Ohio is the best known locality. The Hamilton Group in New York and the Mahantango Formation in Pennsylvania also produce them. Eldredgeops rana, once called Phacops rana, is the species most collectors want.