Construction Crew Uncovers New 20-Meter Dinosaur Species in Brazil

A newly identified dinosaur species, Dasosaurus tocantinensis, has been described from fossils uncovered during construction of a road-rail terminal in Davinópolis, Maranhão state, in northeastern Brazil. The 20-meter-long dinosaur lived about 120 million years ago, and its closest known relative lived in what is now Spain, according to a study published in the Journal of Systematic Paleontology.

The fossils were found by archaeologists monitoring the construction site as part of the environmental licensing process. "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," said Elver Luiz Mayer, a professor at the Federal University of the São Francisco Valley (UNIVASF), who led the study.

Researchers say the ancestors of the Maranhão species likely reached South America through North Africa sometime between 140 and 120 million years ago, when the two continents were still joined within the supercontinent Gondwana. The specimen includes tail vertebrae, a 1.5-meter femur, ribs, foot bones, and arm and leg bones, making it a relatively complete find; researchers believe more fossils from the same specimen remain to be excavated at the site.

Bone microstructure analysis led by researchers Tito Aureliano and Aline Ghilardi of the Federal University of Rio Grande do Norte (UFRN) showed a growth pattern that blends features seen in older sauropods with traits associated with titanosaurs, a group closely related to the new species. Max Langer, a professor at the University of São Paulo who took part in the study, said the finding indicates that some patterns of growth and bone remodeling appeared earlier in dinosaur evolution than previously recognized.

The species name refers to the region: "Daso" means forest, referencing the woodlands that early Portuguese colonizers described as a large tangle, or "maranhão," while "tocantinensis" refers to the nearby Tocantins River.