Domenica Nov 19

Bergamo ... 220 million years ago

The Bergamo area was covered by a vast stretch of water about 220 million years ago, during a stage of the Triassic period termed Norian. The landscape was similar to today’s Bahamas, with a warm, shallow sea and small islands smothered in greenery. The shallow waters would give way to deeper stretches where, at times, the water settled and where oxygen became scarce, to the detriment of life forms. The remains of the organisms settled on the beds of these basins, did not decompose immediately, were then covered by sediments, and were finally fossilized. The extraordinary Norian fossil findings in the Alpine foothills of Bergamo, are world-famous and are of enormous scientific value. The specimens came to light during research campaigns conducted by the museum over the last 40 years at highland locations of the province of Bergamo. The Triassic rocks from the valleys of the Bergamo district have yielded thousands of fossils, collected, processed and studied by the museum’s staff. Some of the specimens are exhibited while others are kept in the Institute’s storerooms. Many of these findings are holotypes. Holotypes are the most markedly representative specimens on the basis of which new species are defined. Some of the specimens are totally unique, belonging to new species which have not been discovered elsewhere. The fossils exhibited in the room “Bergamo ... 220 million years ago” provide an important record of life all those years ago. The panels provide geological and ecological notes on environments of the past. The cabinets may be seen as an imaginary journey on from the depths of this ancient sea to its coastline, into the mainland and, lastly, into the sky.

The central cabinet is a diorama – a reconstructed environment illustrating a habitat complete with its most representative fauna. The areas which have yielded these magnificent fossils have been grouped together at the Sistema Territoriale, grouping this Museum with the Museo Brembano in San Pellegrino Terme, the Monumento Naturale of Val Brunone and the Parco Paleontologico at Cene. The first finding in the fossil deposit at Cene dates back to 1970. The fragment of a small fish with perfectly preserved scales led to a series of research campaigns.

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The cabinets hosting marine species feature large and medium-sized predators, small fish which formed shoals, fish of the shallower waters, invertebrates and large marine reptiles. Cabinet 4 hosts large predator fish, Saurichthys and Birgeria, which differ considerably both morphologically speaking and in terms of their habits. The Saurichthys had a tapering body, and was a rapid swimmer, while the Birgeria was a bulky, heavy fish. On the wall, we see the largest complete Saurichthys specimen found to date, 160 cm in length. The smaller predators include the Thoracopterus flying fish, whose enormous pectoral fins functioned as ‘wings’, enabling this fish to leap out of the sea and briefly glide over its surface. Cabinet 6 displays small fish which, like sardines today, formed shoals. They were hunted by other fish. The habitat of the Pycnodonte lay toward the reefs. The Pycnodonte resembles certain inhabitants of today’s barrier reefs, i.e. round or rhomboid and with flat sides, enabling them to move through the reef and feed. Their teeth were particularly suited to the task of crushing the tough exoskeletons of invertebrates. Cabinet 8 contains a large Paralepidotus, perfectly preserved with its bright scales, strengthened by an enamel-like substance called ganoin. Other marine creatures – invertebrates – account for a large portion of the fossil findings. Cabinet 9 features crustaceans: swimmers, others which have adapted to life on the seabed, echynoderms, gastropods and corals. Cabinet 10 contains immensely important insect findings – indicating that land had emerged nearby. Only rarely are insects preserved in the fossil state. Very little is known about Triassic insects, and there are very few findings like the Italophlebia dragonfly displayed here. Furthermore, the specimen has been perfectly preserved. The extremely delicate wing venations are still clearly visible and they allow us to make a distinction between males and females. In particular, this specimen is male. We also note the presence of marine reptiles such as the Endennasaurus. This species, with its tapered form, evolved as a good swimmer and had no teeth. It may have fed upon small crustaceans. Psephoderma alpinum fed on molluscs, crushing the shells with its large flattened teeth.

220 million years ago, the peaks of the Alps had not yet been raised to the skies. At that time, the area of Bergamo was a stretch of water with scattered islands. The reconstructed environment in a cabinet has been envisaged on the basis of the fossils gathered together in this exhibition. The painted background represents land which has emerged from the sea. Larger species, such as the Phytosaur, are presented alongside flying reptiles. Under the water we see, two Psephoderma and a large fish – the Paralepidotus. The three-dimensional reconstruction reproduces a marine environment. The water’s surface is rendered by a resin construction whose form imitates the forms of waves. Under it we find models of underwater species – schools of small Pholidophorus fish, molluscs, and an Endennasaurus, a long-bodied reptile which seems to be swimming off in search of its next meal. In the lower right-hand corner we see a small fish lying on the sandy seabed. It is in the early stages of the process of fossilization – a process thanks to which, captured in stone, so many species inhabiting this ancient sea have reached us today. Eudimorphodon is the most famous and oldest of all flying reptiles. You will see it as it feeds, to the left of the diorama, above the sea. The fish in its mouth indicates that this Pterosaur was a carnivorous predator.

The cabinets dedicated to land animals include important reptile findings. Some are unknown elsewhere around the world. A cabinet features an extraordinarily important finding – a gigantic Mystriosuchus. The Mystriosuchus is a crocodile-like Phytosaur of a length of about 4 metres. This is one of the few specimens worldwide with a full skeleton. Unlike other currently known Phytosaurs, this organism has adapted extremely well to an aquatic environment. Since its nostrils were positioned on the top of its skull, the Mystriosuchus, with its eyes and mouth under water, could breathe while hunting and feeding on fish. While today’s crocodiles have adapted to life, above all, in fresh water, Phytosaurs lived in the sea. Ttwo other rarities are featured s– the terrestrial reptiles Drepanosaurus and Vallesaurus. These animals, with their prensile tail and long claws, have adapted to arboreal life. Their presence signifies that land, with vegetation, had emerged nearby.

In two cabinets  we find the flying reptiles that, during the Triassic period, would have populated the skies of the Bergamo area. These are the most ancient of all known flying reptiles. Like all Pterosaurs, the Eudimorphodon, Peteinosaurus and Preondactylus were endowed with wings formed out of a sturdy membrane supported by an extremely long fourth digit of the forelimb. These excellent flyers were comparable in size to today’s seagull.  This Eudimorphodon was discovered at Berbenno in the valley, Valle Imagna. The wing tissue has been preserved in part. The last cabinet hosts the Eudimorphodon ranzii holotype. The first Pterosaur extracted from the Cene deposit , this scientifically important specimen, of striking appearance, may be considered the prime example of the Bergamo area’s Norian fauna population. This fossil also contains the remnants of its very last meal. The remnants consist in scales, telling us that the diet of this flying reptile was fish-based.

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