Seas, Lakes and Rivers

Devonian 360-410 million years ago

The Devonian Period is sometimes called the ‘Age of the Fish’ and in this part of the museum you can see fossils of some of the different types that lived at the time. There are examples of jawless fish, fish with armour-plated heads and lungfish - fish which can breathe air. The Devonian Period also marks a time when both plants and backboned animals first began to colonise land as well as the water. You will find early land plant fossils, as well a cast of Acanthostega, an animal from Greenland which had developed some of the key features that made land life possible.

Cephalaspid fish

The first fish to evolve were strange jawless creatures without teeth, called agnathans, which fed on tiny particles of organic material. Some of these early fish were free swimming animals with thin scales and fed on tiny organisms in the sea water. Others, such as the Cephalaspid illustrated here, were more bizare and had horse-shoe-shaped bony head shields and grubbed around on the sea bed. By Devonian times, some agnathans moved from the sea into freshwater.

By Devonian times, the first vertebrate animals with two pairs of legs, known as tetrapods, had evolved from fish, which had two pairs of muscular fins. The first tetrapods, such as the metre-long Acanthostega illustrated here, were still essentially aquatic animals, which spent much of their lives as active predators in lakes and fast flowing streams. However, it is also likely that they were able to use their limbs to drag themselves short distances across wet sediment.

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