The Cerro Chato deposit is located near the Brazilian-Uruguayan border and was discovered 70 years ago . However, the scientists of the time did not have the modern tools they have today and were unable to return. The geological conditions that exist in the area mean that authentic paleontological treasures have been preserved that could help clarify what happened in the “Great Death” , one of the greatest extinction events that have taken place on our planet.
Cerro Chato is a very special place because the conditions that occurred in the area about 260 million years ago, towards the end of the Permian , were ideal for trapping and preserving the remains of organisms. This means that the rocks of the site are full of delicate fossils, especially plants, which usually do not fossilize well because they do not have hard parts.
The outcrop was discovered in 1951 and the paleontologists who found it were surprised by how exceptionally well preserved the Permian remains were. However, without modern technologies such as GPS, they were unable to record exact coordinates, much less retrace their steps . For a time they tried to find the site, but the attempts were unsuccessful, the team abandoned the search and the site was declared lost. Another team of scientists resumed the search and managed to find the place in 2019.
“For decades, the geographic location of this outcrop was unknown,” said Joseline Manfroi, a paleobotanist at the University of Vale do Taquari in Rio Grande do Sul, who has participated in the study describing the rediscovered site. This circumstance inspired the new team of scientists to undertake a massive “treasure hunt” to find it again. “Fortunately, after so long, we will have the opportunity to continue writing the history (of the site), through the fossil record,” Manfroi said in a statement.
At the moment, more than 100 fossils have been found in Cerro Chato, most of them of plants . There are also remains of fish and shellfish. The researchers suggest that some of the plant fossils could be the ancestors of today’s conifers and ferns. And this is only the beginning, they warn.
The researchers believe that much remains to be discovered in Cerro Chato, the area is enormous and they calculate that not even 30% of the deposit has been explored . The new team has been in the area for three years, but the original discoverers were only able to explore the surface of the outcrop before they lost track of it.
The fossilized plants of Cerro Chato could help to better understand the drastic climate change that occurred at the end of the Permian and that triggered what is known as the “Great Dying”, a mass extinction event that ended around 90% of life in our planet . “The fossils we are studying are of global importance, as they are direct testimonies of the environmental changes that took place during the Permian,” said study lead author Joseane Salau Ferraz. “These studies will help us retrieve information about the distribution of these plants around the world.
The study was published May 15 in the journal Paleodest .
Reference: Ferraz, J. et. al. 2022. Rediscovery of the Cerro Chato outcrop, an important fossiliferous site for the Permian Paraná basin. Paleodest. DOI: https://doi.org/10.4072/paleodest.2021.36.75.04
