New dinosaur species discovered after thorough examination of Brazil fossils find

Further research into fossils discovered during construction of a road-rail terminal in Brazil in 2021 has confirmed that the remains belonged to a previously unknown species of dinosaur.

A new study published in the Journal of Systematic Palaeontology identifies the remains as Dasosaurus tocantinensis, a dinosaur that lived around 120 million years ago during the Cretaceous period, as highlighted in the SciTechDaily outlet.

The discovery was made in Davinópolis, Brazil, by archaeologists monitoring the construction site as part of the environmental licensing process. The fossils were initially believed to belong to megafauna mammals that may have lived alongside early humans.

"Given its depth of about eight meters, I realized that it was much older. The age of the geological formation was already known from previous research and indicated that it was material from the transition from the Lower to the Upper Cretaceous, about 120 million years ago," said Elver Luiz Mayer, a professor at the Federal University of the São Francisco Valley (UNIVASF) in Bahia.

Mayer subsequently contacted specialists and helped establish a multidisciplinary team to study the specimen.

Dasosaurus tocantinensis is estimated to have reached around 20 metres in length, making it the largest known dinosaur discovered in the Brazilian state of Maranhão.

Its closest known evolutionary relative lived in what is now Spain, a finding that provides more than evidence of a previously unknown dinosaur group in this part of Brazil. It also points to an ancient biological connection between Europe and South America.

Researchers believe the ancestors of the Maranhão species may have reached South America through North Africa between 140 million and 120 million years ago, when the continents were still connected as part of the supercontinent Gondwana.

"It’s the largest known dinosaur for Maranhão, which has other species, but not sauropods like this one; rather, it has smaller ones, such as the diplodocid Amazonsaurus maranhensis, which was about 10 meters long," Mayer said.

The fossil underwent an extensive preparation process before being analysed in Pará. It was subsequently returned to Maranhão and is now housed in São Luís, the state capital, at the State Center for Natural History and Archaeology Research, which also participated in the research.

The remains are considered relatively complete, with researchers recovering parts of the tail, a 1.5-metre femur, ribs, foot bones and bones from the animal’s limbs.

"Because it includes tail vertebrae, a 1.5-meter femur, ribs, foot bones, and arm and leg bones, this is considered a relatively complete specimen. We believe there are more fossils from this same specimen yet to be excavated at the site," said Max Langer, a professor at the Ribeirão Preto School of Philosophy, Sciences, and Letters at the University of São Paulo (FFCLRP-USP), who participated in the study.

The species’ name also reflects its geographical origins.

"Daso" means "forest", referring to the regional woodlands that early Portuguese colonisers described as a large tangle, or "maranhão". "Tocantinensis" refers to the Tocantins River, as the fossil site is located near its eastern bank.

Fossil growth offers clues to dinosaur evolution

Analyses of the fossil’s bone microstructure, led by researchers Tito Aureliano and Aline Ghilardi of the Federal University of Rio Grande do Norte (UFRN), revealed a growth pattern combining characteristics found in older sauropods with traits associated with titanosaurs, a closely related group.

The findings suggest that some patterns of growth and bone remodelling emerged earlier in dinosaur evolution than previously understood.

The discovery could therefore provide new insight into how certain dinosaurs evolved the ability to reach enormous sizes.

The discovery of Dasosaurus highlights a broader tension in palaeontology. Large construction projects can damage or destroy fossil records, but excavation work can also expose geological layers that would otherwise be difficult for researchers to reach using traditional methods.

"Brazil is a tropical country with dense vegetation. Geologists and paleontologists rely heavily on human activity to excavate, expose the rocks, and reveal the fossils. If we map Brazil’s fossil sites, we’ll see highways and quarries. These projects are important for understanding our heritage. But it’s obvious that specialized monitoring and artifact recovery are necessary, which doesn’t always happen," Langer said.

The researchers believe additional fossils from the newly identified dinosaur may still be buried at the original construction site, potentially providing further information about the species and its place in dinosaur evolution.

By Nazrin Sadigova