A brand new old fish – discovering a fossil salmon from the Messinian of Italy

Davide Olivero (Italy), Giorgio Olivero (Italy) and Rob Hope (France)

In the Manosque Region of south-eastern France, Rob discovered a remarkable little fish fossil in an out-of-the-way abandoned quarry. He cut and tidied the small stone, and took it away. He wanted it not as a collection piece, but to understand it, to read it and decipher it. And this, in a nutshell, is what palaeontology really is.

He needed to know which species the small fish belonged to; from which geological stage had it derived … and, dammit, was this ‘species-discovery’ a first? If it indeed was, it would close gaps of biological time and maybe enhance our knowledge concerning the ever-meandering fish evolution through (a truly astonishing) Deep Time.

He later took the fossil (Fig. 1) to his palaeontologist colleague Davide Olivero, of the University of Lyon’s Geology Department, for a potential identification of it. They chatted for an hour in Davide’s small, cramped and messy (yet orderly) office, before moving on to the Manosque discovery.

Davide said after about … well … three seconds.

“Ah, that’s a Prolebias (goreti?) from the Oligocene of about 25 million years ago. They’re actually quite common.

Davide, who’s also a geologist, has a particular preference for trace fossils due, in great part, to his dad Giorgio, who was an avid collector of fossils, when Davide was just a child. At first, Davide and his dad used to search for rocks and fossils near their town of Turin, in the Piedmont region of north-western Italy. All around the Piedmont hills are several, good quality palaeontological sites (which these days are now protected), containing various kinds of Cenozoic fossils, especially bivalves and gastropods. In other localities, they recovered sea urchins, plant and fish fossils. They also investigated more distant places in France, looking for Jurassic and Cretaceous ammonites.

Over time, they had established a large and diverse collection of fossils, and began to barter and exchange selected specimens with various groups and clubs, mostly in France. In this way, Davide was hooked on palaeontology from a very young age, spending most Sundays cleaning and listing newly found/exchanged fossils in their collection. From this, he slowly built up his own ‘collection’, finally to become a university palaeontologist, using his very own fossils as lecture pieces.

One of those pieces has great scientific importance and is to be found neither in his collection, nor that of his father’s, for it is safely stored in the collections of the Natural History Museum of Turin. This fossil is a fish and not only is it of a great pristine preservation, but is the only one of its kind ever to have been recovered; the holotype is known as Salvelinus olivero (Fig. 2) – a salmonid (often today referred to as a ‘char’ or ‘trout’). The remarkable fossil dates to the last stage of the Miocene, known as the Messinian (about 7 to 5 million years ago). Typifying the Messinian stage is an event known as the ‘salinity crisis’, which is linked to the closing of the Straits of Gibraltar and the desiccation of the Mediterranean Sea – just imagine the Mediterranean being around 4km further out than it is today.

In some areas, huge dry and sandy basins dominated the landscape. At this time, the Piedmont Basin had been transformed into a wide lagoon flooded with brackish waters. Interpretations of various fossils from this area indicate the palaeoenvironment as having a mix of marls and evaporites. And near the city of Alba, south of Turin, several palaeontological sites are simply rife with fossils holding this context.

In 1975, Giorgio Olivero first began investigating these localities. He recovered common fossil fish from both marine and freshwater environments, but also dragonfly larvae. Towards the end of that year, he was searching for fossils in the ‘Rocca del Campione’ site, near the town of Cherasco, on the right bank of the river Tanaro. He was digging a marl layer about 6m above the river, finding small fossil fish like Pachylebius sp. and Aphanius sp., as well as plant remains, but above all, he found … The Fish Fossil.

That was the morning of the 24 November 1965 and Davide remembers it well. The specimen was extracted in two pieces. First was a slab of about 50cm. Part of the fish could clearly be seen. However, the caudal fin was lacking, but was later to be found showing on a second slab. Back home, father and son reconstructed the pieces. The large fish was over 24cm in length and much longer than the usual find from this vicinity. Together, they attempted to identify – through catalogues and listings – the fish they had discovered. Was this really a ‘new’ and unknown old fossils fish?

Fully aware of the potential importance of this remarkable find, Giorgio decided to contact the university of Turin palaeontologist, Carlo Sturani (who was later killed in a field accident that very same year). Sturani had previously studied the entire (preserved) Messinian fauna of the area. Davide clearly remembers that meeting in 1975 between his dad and Sturani, with both men pondering, questioning and speculating over the fossil.

The specimen was taken to the university, where Sturani contacted French specialist, Jean Gaudant, who was also at that time studying an array of fossil Messinian ichthyofauna. He set off for Turin to see the fish and, as expected, the find proved to be exceptional. Other, somewhat similar Salvelinus salmon-type specimens had actually been recovered from other European sites from this period. However, this fossil was of an unknown species.

The salmonids are a fresh water fish, yet spend most of their time in the open sea, only returning to fresh water environments to reproduce and spawn – a life cycle known as ‘anadromous’ – and common knowledge to all those living today in Scotland, Ireland, Norway or Alaska. The discovery of the fossil proved essential for palaeoenvironmental interpretation, hinting at a marine/freshwater river link within the area of the Piedmont basin; perhaps even a major estuary system. Today, these fish live in relatively cold waters. Therefore, we can also deduce, after recovering this fossil, that way back during the Messinian, the climates were cooling; or at least, colder waters were arriving at site, perhaps due to the opening of the Straits of Gibraltar, marking the end of Messinian salinity crisis.

Jean Gaudant was to name the fish Salvelinus oliveroi (Fig. 3), so honouring Davide’s father. The astonishing fossil artefact remains to this day within the confines of the Natural History Museum of Turin. The locality of Rocca del Campione is now classified as Palaeontological Geo-Site N° 147 and is one of the 219 protected geological areas of the Piedmont region.

Giorgio is proud to have found such a rare fossil; a fossil which brought greater understanding and detail toward our distant past.

This being the ultimate prize for a ‘good-collector’.