The excavation for the construction of a railway in the municipality of Davinópolis (metropolitan region of Imperatriz), in Maranhão, revealed a giant dinosaur fossil still unknown to the scientific community.
Among the materials found are a femur of more than 1.5 meters in length, other long bones, such as a possible tibia, feet and hands, several ribs and vertebrae.
The fossil is the first known dinosaur for the region and, possibly, an important record for the evolutionary history of the group of sauropods, who lived in what is now Brazil about 130 millions of years ago, in the period known as the Lower Cretaceous.
Although it is not yet possible to know the species of the new dino, due to the size of the bones and their type, it is likely that they belong to a Titanosaurus, a group of long-necked dinosaurs that appeared at the end of the Jurassic , about 163 million years ago. They lived until the end of the Cretaceous, when they became extinct with the other non-avian dinosaurs millions of years ago).
“It was already known by literature from some records further north of the state, but this is the first large vertebrate fossil for the locality, which generally has finds of fossil fish and plants”, explains Elver Luiz Mayer, paleontologist and professor at Unifesspa (Federal University from the South and Southeast of Pará), responsible for the preparation and study of the dino.
The estimated size of the dinosaur is up to 11 meters long, approximately twice as much as another neck also found in the state of Maranhão, the Amazonsaurus maranhensis, one of the smallest titanosaurs described to date.
But, different from Amazonsaurus, the new specimen is close to the region known as Tocantins of the Itapecuru Formation, while the first was found further north in the state.
The Titanosaur Records Brazilians were described mainly for the regions where the Sanfranciscana, Paraná and Bauru basins are located, in the states of Minas Gerais, São Paulo and Paraná. One of the specimens found with the best state of preservation, including a skull with complete jaws, is the Tapuiasaurus macedoi, found in rocks near the municipality of Coração de Jesus, in the north of MG . It was the first Brazilian sauropod dinosaur to also have a preserved head.
The fossil from Davinópolis does not have any skull material or isolated teeth, at least that it has been located until now. “Although the collection work has been exhausting, there are indications that there is more fossil material in the area because the slope is quite extensive, and has a rocky stratum of about ten meters upwards”, explains Mayer.
Initially, employees of the Brado company, responsible for the earthworks in the region and who found the fossil, believed that it was the bones of giant sloths, animals that lived about thousand years and they became extinct in the last glacial period.
Therefore, a team of archaeologists was called in to accompany the work. They got in touch with Mayer, whose specialty is Quaternary mammals (period known for the last Ice Age). “But when we arrived, we saw that it was something much bigger and that it lived longer due to the depth at which the bones were buried”, he says.
After obtaining authorizations from the National Mining Agency for removal of the material for didactic purposes, with no interest in exploration —fossils are assets of the Union and therefore cannot be explored or commercialized—, the material was taken to the laboratory of the Study Group in Paleontology (GePaleo) of Unifesspa, in São Félix do Xingu . There it is being prepared by Mayer and his team.
Due to the estimated age of the rocks from which the fossil was taken, the Itapecuru formation, it is possible that the new dino is close in age to the tapuia, as the neck of northern Minas is affectionately nicknamed, explains Bruno Navarro, a paleontologist at the USP Museum of Zoology, who defended his master’s thesis at the institution on the evolution of titanosaurus.
“It’s rare to find a large fossil in a good state of preservation. In general, in the group of titanosaurus, it is more common to find vertebrae articulated or not. It’s hard to find well-preserved long bones. The finding is extremely important because it opens a new frontier for understanding the fauna of the region, which until then was known for some fossils of plants, insects and fish”, explains Navarro.
Moreover, knowing that titanosaurus appeared at the end of the Jurassic, but there are records in South America mainly from the Lower Cretaceous onwards, with few older findings, the new dino may bring new information about the evolutionary history of the group.
“Whether he could be a relative of other Brazilian titanosaurs, like Tapuia himself, is unknown. It needs to be studied, but it can bring relevant information about the most primitive characteristics of this group in the region where Brazil is today”, he says.
The paleontological community may even wait anxiously for the description of the new species, but it should still take at least five years.
“To prepare all the material, also considering the impact of the pandemic on students’ access to laboratories, will still be needed around two years. And in parallel, we are going to study the material with the other known sauropods, in order to try to present this fossil to the community as soon as possible”, completes Mayer.