A paleontological site over 251 million years old, lost and found in Brazil!

The history of science (and whatever it is) often reveals unexpected, indeed comical, aspects. In fact, if everyone knows the story of the bathtub byArchimedes and the theory that follows it (fails to demonstrate it using the theorem), or the apple of Newton, discoveries in the most basic sense, to use a fashionable expression, are sometimes the result of pure chance. That’s the way it is Lascaux hule, found by children who in the summer of 1940 had ventured into caves near the village Montignac in the middle of Périgord, or closer to us from Cosquer hulefrom the name of its “inventor” (that is the word), who dived into a bay close by Marseille. One of my friends from Aquitaine who wants to recognize himself in these lines likes to talk about a stroke of luck !

My recent media walks to my press release led me to become aware of a discovery, or more precisely, as we shall see, a rediscovery of a fabulous paleontological site in Brazil. In fact, a site for the less promising named Cerro Chato and which had been updated in 1951 by Emmanoel A. Martins and Mariano Sena – Sobrinhoand is close to the Uruguayan border, either inthe state of Rio Grande do Sul (which can never say enough about the beauty of our Latin language and the accents that carry them).

Yes but here it was 1951 and the geolocation instruments that are familiar to us, such as GPS today, did not exist (inability, I admit, to specify it!). What more was it at Brazil, in the infinity of the rainforest! So much so that for decades the scientists, the paleontologists, were never able to find the place that seemed to have been lost in a wet sleep of green eternity, and from time to time settled in a torn silence. .

But since 2019, eurekaaccording to new research conducted by a scientific team consisting of researchers from three universities inrio grande do sul stat, the site was finally found and especially new sedimentary layers were explored. So says spring off Cerro Chato corresponds exactly to deposits corresponding to Medium / Late Perm. It is located northwest of the city Dom Pedritogeographical coordinates 30 ° 53′16 ”S 54 ° 54 ′ 50” W, and sits on a plateau about 190 meters above sea level.

A rich (even very rich) place of fossils derived from Permian be a period (click) which extends from 299 million years to 251 million years. The first fossils found in 1951 came mainly from plants, some fish and molluscs. However, the stubbornness of the Brazilian researchers had remained intact over time, convinced that the updates were only the tip of the iceberg.

paleontology discovery fossils brazil
Late-perm mass extinction.
Credit: J; Penn and C. Deutsch, fossil drawings by E. Haeckel, Photos W Kaveney (Blue Crab), H. Fjeld (Atlantic cod), J. White (Chambered Nautilus)

In addition, what happened on this site millions of years ago telescopes in a strange way our current affairs and our present concerns. In fact, you should know that at the end of Permian, there has been a climate change on Earth that has caused almost 90% of living things to disappear. It is estimated that almost 90% of the marine species and more than 70% of the terrestrial species were extinct, ie. the largest mass extinction ever known on the entire planet. Some advanced hypotheses attribute this phenomenon to acid rain caused by volcanic eruptions in present-day Siberia.

The results of these excavations have just been published in newsletter from the Brazilian Society of Paleontology (Click), we present a summary.

Some data

What are we learning there?

paleontology discovery fossils brazil
Examples of fossils collected from the Cerro Chato protrusion

Historically, the fossil-bearing deposits are located inState of Rio Grande do Sul is characterized by the abundance and diversity of organisms that have inhabited the region through geological time, especially with regard to the fossil-containing deposits of Permo-Triassic. In the central region of the state where the municipality of Santa Maria is located, one of the largest concentrations of Triassic-vertebrate fossils in the world is recorded (Schultz et al., 2020). Some nearby municipalities, such as Mata and São Pedro do Sul, are known to reveal fossilized trees, often of large size, possibly found in growth position (Minello, 1995), and Mata is considered one of the most important paleobotanic sites. South America (Guerra-Sommer & Scherer, 2000).

Globally, the extinction that ended the Permian period (~ 298 Ma – 254 Ma) marks the disappearance of more than 90% of the living species (Benton & Harper, 1997) and is recognized as the largest extinction in mass in the geological record. . The events leading up to this extinction are still debated, but the best supported hypotheses include environmental, climatic and paleogeographic changes, episodes of oxygen deprivation in the oceans (decrease in the amount of oxygen), global warming of the planet, volcanism and possible extraterrestrial influences.

A likely combination of several of these factors has severely affected marine and terrestrial environments (Yin et al., 2007). Since the processes that triggered this great extinction, as well as the reaction from biota (ie animal and plant life) for this event, which is not yet fully understood, provides studies in areas where rocks from the Permian period originate a promising opportunity to recover data on this particular interval in the history of life on Earth. They also make it possible to understand the biology of organisms that have been eliminated or that have survived extinction. In this context, the fossil deposits that present a unique conservation and a large biotic representativeness are particularly interesting.

These layers turned out to exhibit the registration of new macrofossils from lycophytes (plants allegedly related to ferns), from pteridophytes (plants giving neither flowers nor seeds) and sphenophytes (plants including all horseradish), petrified wood as well as fish scales.

The Cerro Chato protrusion is an important fossil site for understanding the environmental changes that took place under Perm in Paraná-bassinet. The site retains a unique fossil-containing content that documents an abundant association of fossils that are representative of the flora alongside lake and lagoon systems during the continentalization of the deposition systems in Gondwana.

The investigations continue and will be the subject of new publications, we will of course not fail to mention them in the columns of VUKALI.

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