The presence of dinosaurs in different regions of Brazil has been known by researchers for a long time. Important fossils have already been discovered, but there was no evidence that they inhabited the Amazon region. 
Now, researchers from the Federal University of Roraima (UFRR) have managed to identify, for the first time, evidence that animals lived in the Amazon more than 103 million years ago.
The main evidence was more than ten footprints from the Jurassic-Cretaceous era identified in the region known as the Tacutu Basin. The records were located in the city of Bonfim, in the north of Roraima.
However, it is not possible to identify with certainty which types of dinosaurs these footprints belonged to, but it is possible to know, from them, which groups lived in the region. Among them are raptors, ornithopods (bipeds and herbivores), as well as xireophores, which have a type of bone armor in the upper part of their bodies.
Difficulty
The Amazon region has always presented few archaeological discoveries because the rocks there were exposed and went through the weathering process. This phenomenon causes wear and decomposition of the rock, which makes it difficult to preserve fossils.
According to researcher Lucas Barros, who found the footprint, the preservation of bone material only happens when the rocks are buried.
“Tacutu would be a valley with several river channels that flowed together. It was a place with a lot of water and a lot of vegetation”, explains the researcher, who recently completed a master’s degree on the subject at Unipampa.
“If you have a valley with a lot of humidity, the river bars will also be wet. After the animal makes this footprint, it loses moisture over time and becomes hard. This allows it to resist the burial process.”
Over thousands of years, the buried footprint solidifies and becomes a rock that can, even when exposed, resist the erosive and weathering action of the soil.
A small savannah vegetation in the Tacutu Basin also allowed the preservation of the footprints.
“This patch of savannah allows us to find outcrops in the rocks and check if there is anything with fossil content there. [Isso possibilita] that we also discover fossils of invertebrates and plants, fossilized trunks and impressions of leaves,” explains Barros.
11 years of research
The dinosaur footprints were identified in 2014, in a field activity by UFRR geology students, led by professor Vladimir Souza. At the time, the university did not have any specialists in paleoecology (which studies the relationship between fossil organisms and their past environments), nor the necessary equipment to carry out the analysis of the footprints.
Thus, the project ended up being shelved and the discovery ended up not being publicized.
“If we publicized this at the time, other people would come and take the research for themselves,” says Souza.
In 2021, the study was reactivated by Barros, who transformed it, with professor Felipe Pinheiro, from Unipampa, into a master’s thesis. Barros began mapping places that had trace fossils, which are traces of the presence of organisms that lived in the past.
Identification of footprints begins with the photogrammetry technique, in which a high-fidelity 3D model is created.
“This allows us to digitize the model on a very faithful scale. That’s how we describe these footprints. That’s what I did during my master’s degree, I described these footprints and discovered new outcrops”, he explains.
Next steps
Barros estimates that there are hundreds of footprints in the Tacutu Basin. At this time, the researcher is investigating footprints located in the Jabuti indigenous land, where four areas with scientific value have already been found.
Many footprints are found in private areas, which prevents them from being fully studied. Some farmers fear that new research will lead to the demarcation of their land, the government’s seizure of their properties, or a lack of adequate compensation.
*Intern under the supervision of Odair Braz Junior
