The open ocean has a rich fauna that includes fish, arthropods and echinoderms.

Bothriolepis maximus

Bothriolepis maximus was the largest Bothriolepis species. One fossil shows the joint of the left pectoral fin. The other clearly shows the structures of the belly shield’s left front section. The area around the joint is smooth where a protective capsule was attached.

Bothriolepis maximus

Bothriolepis maximus was the largest Bothriolepis species. One fossil shows the joint of the left pectoral fin. The other clearly shows the structures of the belly shield’s left front section. The area around the joint is smooth where a protective capsule was attached.

Bothriolepis canadensis

Parts of a Bothriolepis skeleton lie in a jumble. Openings for the eyes and nose can be seen in the skull. Behind the skull is the inside of the belly shield which consists of four large parts and a small plate in the centre. The back shield has been partially damaged and broken apart. The long, armoured pectoral fin still remains attached to the belly shield.

Methacantina

This trilobite was a predator that fed mainly on worms and other small animals. Its shell was thick and formed a dense, spiny defence when it curled into a ball to protect itself against larger predators.

Crotalocephalina & Phacops

These two trilobite species had very well-developed eyes with unusually large lenses that can be seen with the naked human eye. The lenses gave them sharper vision than that of most arthropods, an advantage both when they searched for food and when they were threatened by larger predators. They belonged to a large group of trilobites, most of which were predators

Cornuproteus

Cornuproteus was a trilobite that fed mainly on edible particles it found by munching through the mud on the ocean floor.

It belonged to a group of trilobites which had evolved a new type of larvae that lived like plankton and were thus able to spread over large distances. That was also of great advantage when the environment changed drastically toward the end of the Devonian Period and all other trilobites became extinct.

Cephalaspis

Fossil of a deformed head shield from a jawless fish. Such fish were armoured, somewhat like shrimp, but the armour was made of bone tissue. Seen here is the inside of the shield. It is probable that the head shield could not change size, but instead formed when the fish was fully grown.

Cephalaspis was among the most advanced of the jawless fish, most of which had evolved pectoral fins, dorsal fins and a powerful tail fin.

Osteolepis

All the fish displayed here were of the same species. They probably lived together in a ”school” and died at the same time, possibly due to a bloom of toxic algae.

The approximate meaning of osteolepis is ”scales of bone tissue” and, like all other palaeozoic sarcopterygian fish, its armoured head and thick scales were covered with a shiny layer called cosmin.

Dicranurus monstrosus

Despite its strange appearance, Dicranurus was a trilobite. The many and long spines on every part of its body probably served to defend it against such predators as fish with sharp jaws.

When Dicranurus curled into a ball, the spines stuck out in every direction and the predator had trouble getting at its prey. 

Codiacrinus & Imitatocrinus

These two species lived side-by-side, capturing plankton and tiny animals with their branching arms.

The sea lilies could not attach their stems directly to the soft bottom mud, but needed a hard anchoring base. That could be the shell of a dead mollusc or another sea lily. Several sea lilies are often found bunched together, competing for space on the same foothold.

Calycanthocrinus

This sea lily had a thin, narrow crown and a very long stem.

Calycanthocrinus lived like other sea lilies, by filtering plankton and tiny animals from the water with its flexible long arms. In order to do that efficiently, it needed to rise above the ocean floor and therefore had a long stem that was attached to some hard object on the bottom.

Drepanaspis gemuendenensis

What look like pectoral fins on either side of the head are not fins at all, but large plates which covered the gills. The tail fin was covered with thick, hard scales and sharp spikes. It is the presence of the mineral pyrite, also known as fool’s gold, which causes the fossil to shine golden.

Loriolaster

Loriolaster was a brittle star with broad skin flaps between the arms. It fed on microorganisms on the ocean floor, and may also have eaten carrion. 

Urasterella

Urasterella was a starfish with thin arms that fed on small animals on the ocean floor. Fossils of starfish are rare, partly because starfish rapidly fall apart after dying, but perhaps also because they were not so common then as they are today.

Nahearis

Nahecaris was a fairly large crustacean that looked like a shrimp. It had a large protective shell around its head and midsection.

Nahecaris lived on the ocean floor, with its shell spread out like a sort of tent. In the space under the shell, the animal stirred up the sediment with its many limbs and sorted out everything that was edible.

Helmerosteus laticeps

The placoderm Helmerosteus is a ”little brother” of Harrytoombsia, a model of which you can see in the display case. Visible on the skull are the borders, or ”sutures”, between the plates. These are growth zones which enable the skull to become larger as the placoderm grows.

Like all placoderms, Helmerosteus had jaws but no teeth. The eyes were protected by bony plates, just as in extinct ichthyosaurs and in modern birds.

Eusthenopteron foordi

This fossil of Eusthenopteron shows the inside of its skull. Rows of small teeth can be seen in the outer parts of the jaw; fewer but much larger teeth can be seen on the inside.

The fossil indicates that Eusthenopteron foordi was related to early tetrapods such as Ichthyostega and the amphibian Eryops since their teeth were similar. Models of those species are displayed elsewhere in the exhibition.