The Silurian, Ordovician and the Cambrian

When: 543 to 417 million years ago.

Animals: Invertebrates like trilobites, graptolites, molluscs, brachiopods, echinoderms, corals, and sponges. Vertebrates (animals with back bones) also appear in the Cambrian, fish-like creatures swim in the oceans for the first time. All these animals live in water: there was no animal life on land at this time.

Plants: Seaweed, and other algae grow in the oceans; primitive plants move onto land in the Ordovician.

Firsts: The first complex animals with hard body parts appeared in the Cambrian period. Before this all animal life was soft-bodied!

Lasts: The strange and fearsome predators Anomalocaris and Opabinia, which swam with fleshy lobes along their bodies, became extinct by the end of the Cambrian.

Notes: Most plants and animals lived in the sea, but some moved onto land and into freshwater in the Ordovician.

It is a type of mollusc called a nautiloid. Nautiloids are related to ammonites and other animals like squid. This one was found near Ludlow in Shropshire and is from the Silurian period. It is just over 420 million years old.
This type of nautiloid has a long straight shell. Most fossil, and all modern, nautiloids have coiled shells, and look more like ammonites..

Do you know what these fossils are?

These are trilobites. Trilobites are an extinct group of arthropod - animals with jointed exoskeletons. These ones were found near Malvern in Worcestershire and are from the Silurian period. They are about 425 million years old.

Trilobites come in a variety of shapes and sizes.

These are fossil gastropods (snails) that lived in the sea. These ones were found near the Welsh borders and are from the Silurian period. They are about 425 million years old.

This is a fossil bivalve mollusc and looks just like a shell you may find on the beach today. This one was found near Malvern in Worcestershire and is from the Silurian period. It is about 425 million years old.

These are fossil crinoids or sea lilies. They were found near Dudley in the West Midlands. They are from the Silurian period, and are about 425 million years old.

Sea lilies are echinoderms - they are related to starfish and sea urchins.

These are fossil brachiopods. Although they look like the shells of bivalve molluscs like cockles and mussels, they are actually from very different animals. These ones were found near Malvern in Worcestershire. They are from the Silurian period, and are about 425 million years old.

This specimen is a model of a eurypterid or sea scorpion. It was made by studying well preserved fossils found in Estonia, and gives us a better idea of what these animals looked like. This type of sea scorpion is from the Silurian period.

This is a trilobite. Trilobites are an extinct group of arthropod - animals with jointed exoskeletons. This one was found near Powys in Wales. It is from the Ordovician period, and is about 450 million years old.

Trilobites come in a variety of shapes and sizes - so have a look and see if you can find any others on the previous page.

These are trilobites. Trilobites are an extinct group of arthropod - animals with jointed exoskeletons. These ones were found in Shropshire. They are from the Ordovician period, and are about 450 million years old.

Trilobites come in a variety of shapes and sizes - so have a look and see if you can find any others on the previous page.

These are graptolites. Graptolites are an extinct group of animal that lived in the sea, floating near the surface and feeding on tiny plants, animals and food particles. These ones were found near Dyfed in Wales. They are from the Ordovician period, and are about 470 million years old.

This is a mass of fossil brachiopods. These specimens were found in Gwynedd in Wales. They are from the end of the Cambrian period, and are about 495 million years old.

Brachiopods are shelled animals, and although they may look like bivalve molluscs (cockles and mussels), they are not related to them.

These are trace fossils. They are the burrows of ancient soft-bodied animals. Just like the dinosaur footprints that you can see on the front lawn of the museum, these fossils show the trace of animals, and give us an idea of the way they lived.

This specimen was found in Norway. It is from the beginning of the Cambrian period, and is about 545 million years old.

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The Silurian, Ordovician and the Cambrian

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