A “lost” fossil treasure has just been rediscovered 70 years later

EXCURSION OF THE FOSSILS

When they began documenting the fossils, researchers suspected that this was the location that had been described in the early 1950s, but it wasn’t until 2021 before it could finally be confounded. We owe this endorsement to Joseane Salau Ferraz, one of the students on the Masters in Biology led by Felipe Pinheiro.

She trawled through an online fund of old scientific journals to find references to fossils found on land owned by a family named Goulart, and she didn’t expect to find much but, buried in the scientific corpus of decades past, in a yearbook of the Brazilian Academy of Sciences, was a 1951 article by Emmanoel A. Martins and Mariano Sena Sobrinho.

In it, the two researchers describe a place that is located directly on the edge of Dom Pedrito: Cerro Chato, the “flat hill”. At this point we had “recently discovered fossiliferous outcrops […] offers very favorable conditions for stratigraphic observation and contains fossils in good condition. The article also mentions a large area full of petrified vegetation.

When she saw what was in front of her, she immediately called Felipe Pinheiro. “It was a huge surprise,” she recalls. This confirmed everything we thought we knew up to that point. »

With funding from the city of Dom Pedrito and area universities, the researchers began digging, using a chainsaw and an excavator to gradually remove rocky sediment from the mound. Each time a layer was removed, the team would come armed with hammers and brushes to do the hardest part of the job, extracting the fossils from the rocks.

To date, they have dug nearly two meters and uncovered deeper strata that contain even more fossils than on the surface; again fossils of fish and mollusks, but also isolated scales and a certain amount of old plants.

CONNECT THE PAST AND THE PRESENT

With government funding, the researchers plan to continue excavations at Cerro Chato over the next three years. In the meantime, Joseane Salau Ferraz has begun to analyze what has already been collected as part of her master’s thesis.

Much of the fossilized vegetation has been excavated in fragmentary form, but at least one complete plant exists. Their finds include roots and seed clusters from conifers that quickly recovered from the mass extinction and then multiplied. Several pteridophytes (vascular plants that disperse spores rather than produce flowers or seeds), including ferns, horsetails, and lycophytes, have also proven successful. In the subgroup of lycophytes, which today is dominated by species that do not grow taller than 30 centimeters, there are plants that could reach a height of over 30 meters in the Permian.

But it was the ferns that impressed Joseane Salau Ferraz the most. “They are so well preserved that you can even see the veins on their leaves, which is exceptional for this region,” she explains.

One fern in particular helps her learn more about how these plants conquered the landscape millions of years ago. She belongs to the genus Pecopteris and is the first of its kind to be discovered in Rio Grande do Sul. Possibly a new species in its own right.

“This is really important,” stresses Joseane Salau Ferraz, because now we will be better able to understand the distribution of these plants that lived in the Permian. »

While the Permian is well documented in regions such as North America, South Africa, China, and Russia, it has not been extensively studied in South America. With the newly discovered fossils, the research team hopes to better understand the factors that contributed to the largest extinction event on Earth.

The Permian ended when more than 90% of species were wiped out by a series of titanic volcanic eruptions in Siberia. This period of galloping warming is particularly important for scientists trying to assess the threat of the sixth mass extinction we are currently witnessing.

“If what we are currently witnessing is the result of human behavior, the extinction mechanisms are still similar to those that took place in the Permian,” says Felipe Pinheiro. We are intervening in the same biogeochemical cycles (carbon cycle, nitrogen cycle) that during the Permian, disturbed by natural factors, led to the death of 90% of species. So when we study this extinction, we study the present. »

Celestino Goulart hopes this wealth of fossils will also help those visiting Rio Grande do Sul understand the importance of this type of paleontological site. He is already studying the possibility of turning Cerro Chato into a place for cultural and educational tourism, in order to preserve what is still underground.

“When we were kids, like most kids, we had a few toys related to things like that,” recalls Celestino Goulart, who has six siblings. “But we didn’t imagine at the time that we’d have that right under our noses, in our own backyard, in real life. »

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