An article in the journal Palaeontology sheds light on the Tridentinosaurus antiquus, one of Italy’s best known reptile fossils, dating back 280 million years: the results of tests conducted by a research team involving the Museum of Natural Sciences, Alto Adige, MUSE – the Museum of Sciences in Trento, the Geosciences Department and the Museum of Nature and Humankind of the University of Padua, and University College Cork (Ireland), reveal that the carbonaceous trace on the surface is not skin, but a thin film of colouring applied to the specimen around 100 years ago.

Discovered in 1931 near Stramaiolo, on the Pinè Plateau in the Trentino region, the diminutive reptile Tridentinosaurus, now preserved in the Museum of Nature and Humankind of the University of Padua, is of importance not only for its undeniable value as a fossil dating from the Permian period (300 to 250 million years ago), but also for its unusual appearance, attributable to the fact, it was thought, that the soft tissues — the skin, in particular — had benefited from a rare process of preservation. It is precisely a lack of such fossils that caused the team to have doubts concerning the methods used in preserving the fossilized state of the specimen, and to investigate further.

Under the surface: detailed analyses and unexpected discoveries

Accordingly, an international team sponsored by the research project “Living with the supervolcano”, with funding from the Autonomous Province of Bolzano, undertook a multidisciplinary study aimed at examining the minutest details of the specimen that might reveal the secrets of this small reptile.

“Exceptionally well preserved fossils are rare, but they can show secrets of the colouring, the internal anatomy and the physiology of extinct animals, giving us a clear view of organisms from the past”, says Valentina Rossi, researcher at the University of Cork, and leader of the project. “The real surprises come along when modern techniques enable us to unpick the hidden secrets of fossils”. 

Tridentinosaurus: at last, a detailed study

With the aid of powerful microscopes, and the very latest chemical and diffraction analysis methods — including single crystal x-ray microdiffraction and infra-red spectroscopy — the fossil gave up its secrets: it seems that shortly after its discovery, the entire specimen was treated with a coating material similar to a lacquer. “Coating fossils with varnishes and/or lacquers was an ancient method of preservation, in an age when there were no other more suitable methods of protecting specimens from natural deterioration”, explains Mariagabriella Fornasiero, curator at the Museum of Nature and Humankind in Padua, and co-author of the study.

The true nature of the carbonaceous coating

The analysis of various microscopic samples taken from the fossil also revealed another truth: there is no trace of any biological structure preserved by the carbonaceous coating. In effect, the chemical composition of the dark surface layer corresponds to that of commercial pigment known as “bone black”, which is produced to this day by charring animal bones. Says Valentina Rossi: “The puzzle was solved analysis after analysis. What had once been described as carbonized skin was in point of fact only a coloured paint”.

“The singular preservation of the Tridentinosaurus was a source of puzzlement to palaeontologists for decades”, confirms Evelyn Kustatscher, researcher at the Museum of Natural Sciences of Alto Adige and co-ordinator of the research project. “Now we know why! What we had thought to be skin is in reality not skin, and consequently this is not the oldest fossil mummy in the world”. 

In search of the true identity

The analyses conducted did however confirm the value of the fossil in helping to reconstruct the ecosystems of the Permian period (approx 280 million years ago); the bones of the rear limbs are in fact authentic, as are certain osteoderms — structures similar to crocodile scales — which are still being explored and examined by researchers in a bid to reveal the true identity of TridentinosaurusMassimo Bernardi, director of the Office of research and museum collections at MUSE, and co-author of the study, makes the point: “Far from being mere exhibitors of the heritage they have in their care, museums are dynamic places dedicated to the research and constant redefinition of specimens and practices. Thanks to the rigour and effectiveness of the scientific approach, the ceaseless practice of gathering evidence, formulating hypotheses and putting them to test in pursuit of the most reliable theory possible, the Tridentinosaurus now has a new story to tell, in which geology and human events are interwoven unexpectedly and intriguingly”.

A final word from Fabrizio Nestola, professor at the Geosciences department of the University of Padua and scientific director of the Museum of Nature and Humankind, which houses the specimen: “It is essential for a team of researchers always to ask questions, even to the point of challenging received wisdom. The Tridentinosaurus is proof of this: it urges us to keep investigating, in search of its true origins, to formulate new hypotheses and provide answers to the questions that surround it. The job of our museum is to inform the public as to the findings of knowledge newly acquired, fuelling a debate that is scientific, certainly, but cultural first and foremost”.

The full article can be found at this link