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A newly identified dinosaur species discovered during construction work in northeastern Brazil is providing fresh clues about how giant dinosaurs spread across ancient continents.
Named Dasosaurus tocantinensis, the species is described in a study published in the Journal of Systematic Palaeontology. The dinosaur was about 20 metres long and lived roughly 120 million years ago during the Cretaceous period.
Its fossils were discovered at the site of a rail-road terminal under construction in Davinópolis, a city in Brazil’s Maranhão state.
One of the most significant aspects of the discovery is the dinosaur’s evolutionary link to Europe. Its closest known relative lived in what is now Spain, suggesting that the lineage once inhabited areas that are now separated by the Atlantic Ocean.
Researchers believe the ancestors of Dasosaurus tocantinensis reached South America through North Africa sometime between 140 million and 120 million years ago, when the landmasses were still connected as part of the supercontinent Gondwana.
Maranhão’s largest known dinosaur
At around 20 metres long, Dasosaurus tocantinensis is the largest dinosaur known to have been found in Maranhão.
“It’s the largest known dinosaur for Maranhão, which has other species, but not sauropods like this one,” said Elver Luiz Mayer, a professor at the Federal University of the São Francisco Valley (UNIVASF).
Maranhão is also home to fossils of the smaller diplodocid Amazonsaurus maranhensis, which measured about 10 metres in length.
Mayer, who normally studies Quaternary-period mammals, became involved in the discovery in 2021 while working in São Félix do Xingu in Pará state. Archaeologists monitoring the Davinópolis construction project as part of environmental licensing requirements had uncovered the fossils.
The remains were initially believed to belong to large prehistoric mammals that may have lived alongside early humans. However, Mayer suspected they were much older.
“Given its depth of about eight metres, I realized that it was much older,” he said. The age of the geological formation indicated that the fossils dated to the transition from the Lower to Upper Cretaceous, around 120 million years ago.
Mayer then contacted specialists and assembled a multidisciplinary team to study the specimen.
Remarkably complete fossil
The fossils underwent extensive preparation before being examined by researchers in Pará. The specimen was later returned to Maranhão and is now preserved in São Luís, the state capital.
It is housed at the State Center for Natural History and Archaeology Research, which also participated in the study.
The discovery adds to scientists’ understanding of the distribution and evolution of giant sauropod dinosaurs at a time when South America, Africa and Europe were undergoing major geological changes that would eventually reshape the continents.