Ammonites can amaze us with their bizarrely shaped shells, which often came about close to the many great crises they suffered during the long 300-million-year life. Macroscaphites starts off as a normal ammonite rolled up in planispiral shape, then straightening out and ending with a hooklike bend. The planispiral, gas-filled part kept the shell stable in the water, while the organism itself lived in the hooklike section.

Bellerophon, a planispiral snail, is one of the best-known fossils of the Dolomites: it lends the Bellerophon Formation its name and bears witness to the definitive arrival of the sea at the end of the Permian period. This exhibit shows the snail together with a large Tainoceras malsineri, ancestor of today's Nautilus cephalopod. The large number of microfossils (calcareous algae and foraminifers) testifies to the wide variety of life forms in existence shortly before the mass extinction.

Ammonites sometimes look very similar to each other thanks to their history spanning over 300 million years. They have a planispiral shell more or less marked with ridges and tubercles. Yet they can be classified also on the basis of inner characters, so that there is never a perfect repetition. As a result, this ammonite from the Cretaceous period may always be distinguished from its ancestors.

This large bivalve mollusc ruled the mud flats of the largest Triassic carbonate platform, for good reason called Dolomia Principale (Main Dolomite), stretched throughout the Dolomites and over a good part of the western Tethys. The dolomitization process almost always dissolved its thick shell, leaving only the sediment that filled the shell itself.

The recovery of coral reefs reached a first peak 235 million years ago, and the specimens found around Cortina are an excellent example of this. The extraordinarily well-preserved ecosystem of corals, sponges and molluscs is a unique paleontological feature of the Dolomites, testifying to an apex in marine biodiversity across the whole Mesozoic era.

These large gastropods were ornamented with spines or tubercles, partly to reinforce their shells and partly to be able to hide in amongst the gravel right at the contact with the rough waters, where this association used to live. The organisms were then transported into deeper waters forming the deposits we now call 'Pachycardia Tuff'.

These spherical snails could grow to a considerable size and were able to remain stable on powerful waves thanks to their smooth surface. We can imagine these molluscs were brightly coloured, as a few specimens reveal traces of colour, even if we do not know yet which colour they were.

This bivalve mollusc makes up 90 percent of the fossils in the Pachycardia Tuff layers, which explains where they got their name from! These layers of coarse sediments (sandstone and conglomerates with rounded gravel of volcanic origin) are only found on Alpe di Siusi and represent deposits containing organisms that lived on the beaches of the volcanic islands, where the waves were very strong. Pachycardia has a very thick shell that made it resistant to the force of water.

Nowadays, coral reefs are one of the most spectacular environments thanks to the beauty, shape and colour of its organisms. This ecosystem finally managed to recover during the Late Ladinian period, after a big crisis following the mass extinction. The large coral colonies found in abundance on the Alpe di Siusi plateau bear witness to this significant biological event.

Daonella are typical bivalve molluscs from the Middle Triassic period (247-237 million years). Their thin, flat shells were reinforced with radiating ribs that, beside their circular to sub-triangular shell outline, characterize the species. D. lommeli is one of the largest and most widespread species. As it is often found in rocks deposited in the open sea, it is presumed that it lived afloat the water thanks to its thin, wide shell.