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Fossil discovery in Rio Grande do Sul shows diverse ecosystem that survived during drought in the Permian period
A significant scientific discovery was recorded in southern Brazil, bringing new evidence about the environmental dynamics of the planet in the distant past.
An extremely diverse swamp forest developed between 273 million and 260 million years, during the Permian period, in the region that today corresponds to the southwest of Rio Grande do Sul, near the border with Uruguay.
This ecosystem included trees, ferns, lakes, and primitive aquatic organisms, forming a humid environment in contrast to the increasing aridity of the region at that time.
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Larger than Belgium and nestled at the mouth of the Amazon, Marajó Island is a giant that Brazil has forgotten, surrounded by water and energy on all sides, yet still isolated, poor, and dependent on diesel brought by barge.
Discovery surprises scientists in arid landscape
The identification of this forest surprised researchers, especially because it occurred in an area that already showed signs of desertification.
According to paleobotanist Joseane Salau Ferraz, from the Federal University of Pampa (Unipampa), the lead author of the study published in June in the journal Journal of South American Earth Sciences, the diversity found was not expected in a dry environment.
During the analyses, about 200 fossils were collected, with 103 well-preserved specimens revealing species adapted to humid conditions.
In addition, traces of fish scales and mollusks confirmed the existence of lakes surrounded by abundant vegetation.
Natural oasis protected species before the great extinction
This environment functioned as a true ecological refuge, preserving forms of life that existed before the largest extinction in Earth’s history.
About 252 million years ago, at the end of the Permian, around 90% of species were eliminated, in an event associated with intense climate changes and volcanic activity.
According to studies published in December 2024 in the same scientific journal, large isolated lakes in the interior of continents may have played a crucial role in the survival of some species.
However, in the marine environment, the scenario was different, as the increase in temperature, the presence of volcanic ash, and the drop in sea level caused mass extinctions.
Excavations reveal fossils with a high level of preservation
The excavations began in 2020, at the paleontological site Cerro Chato, located in Dom Pedrito (RS).
According to Joseline Manfroi, a researcher associated with the University of São Paulo (USP), the fossils were visible from the start, indicating the richness of the site.
The analyses showed impressive details, such as preserved veins in the leaves and visible vascular tissues in the stems, in addition to complete specimens with roots, stems, and leaves connected.
Diverse vegetation with a predominance of lycophytes
The forest had a varied composition, although about 73% of the fossils belong to lycophytes, a group of primitive plants.
Among them, the species Lycopodiopsis derbyi stands out, which could reach up to 30 meters in height, with a slender stem and rounded crown.
Additionally, the environment included large conifers, Glossopteris, and sphenophytes, small plants similar to the current horsetail.
At the same time, regions like São Paulo and Tocantins housed tree ferns up to 15 meters, similar to current species in the Atlantic Forest.
Formation of Pangea intensified aridity
The climatic transformation is directly linked to the formation of the supercontinent Pangea, completed about 252 million years ago.
According to paleontologist Felipe Pinheiro, from Unipampa, the areas furthest from the sea became progressively drier, reducing the extent of forests.
As a result, vegetation began to exist only in isolated regions, such as the oasis identified in southern Brazil.
Older records reinforce environmental changes
Studies conducted by Júlia Siqueira Carniere, from Univates, identified even older fossils, about 296 million years old, in the municipality of Pântano Grande (RS).
These records indicate the existence of swampy environments with a more humid climate before the intensification of aridity.
In addition, the species Franscinella riograndensis was identified, expanding knowledge about the flora of the period.
Connection between continents and global impact
The presence of fossils of Glossopteris in both South America and Africa reinforces that the continents were united in the past.
At the same time, an even more diverse forest developed in the south of present-day South Africa, but eventually disappeared under similar conditions.
This set of evidence shows that wet environments could exist even in predominantly arid scenarios, challenging traditional interpretations of paleontology.
In light of these discoveries, an inevitable reflection arises: how many other ancient ecosystems remain hidden and could transform what we know about the history of the Earth?
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