In the 1970s, paleontologists in Brazil discovered the fossilized one-toed tracks of a mysterious dinosaur. Now, they’ve finally identified the animal that left the prints behind as it moved across the prehistoric desert 90 million years ago. They’ve uncovered 40 percent of the bones from a 5-foot-long, 2.5-foot-tall, 33-pound therapod dinosaur from the same group as Tyrannosaurus Rex and velociraptor.
The discovery was made in the Cruzeiro do Oeste municipality of Parana state in southern Brazil, reports Agence-France Presse. Researchers first uncovered a small, quarter-inch-long tooth. When they excavated further, they discovered the unusual foot of the dino as well. The foot itself wasn’t one-toed, but in fact three-toed; however, the dino seems to have rested all its weight on its middle toe when it walked, making it monodactyl—the first time that adaptation has been found in Brazilian dinosaurs.
“It’s incredible that, nearly 50 years later, it seems that we have discovered what type of dinosaur would have produced those enigmatic footprints,” says Paulo Manzig of the Paleontology Museum of Cruzeiro do Oest and co-author of the new findings published in the journal Nature Scientific Reports.
Dubbed Vespersaurus paranaensis, the dino would have been similar to other meat eating Noasaurinae theropods of the time, chasing after prey on two feet and attacking them with three claws on each six-inch foot.
Other monodactyl animals, like horses and ancient kangaroos, lost their extra digits in order to run and jump more efficiently. It’s likely the new dino also developed its one-toed gait for similar reasons, as Luiz Eduardo Anelli, a paleontologist and Brazilian dino expert not involved in the study, tells Jill Langlois at National Geographic.
“The monodactyl reveals so much, including the anatomical diversity of these animals, which reflects their different ways of life,” he says. “Dinosaurs had adaptations to dig burrows, glide, climb, swim, fish, open furrows in the ground for their eggs, run, fly. They were extraordinary animals.”
It’s hard to say at this point how being monodactyl helped Vespersaurus. But other monodactyl dinosaurs are kind of weird. In particular, the alvarezsaurian dinosaurs found in China had short forelimbs that were monodactyl, developing into a single large claws, which may have allowed them to rip their way into ant and termite nests similar to the techniques used by modern anteaters or aardvarks.
Researchers will continue to study why Vespersaurus was monodactyl, and the hope that means more attention will be paid to fossil beds in Parana. While about 40 dinosaur species have been found in Brazil, none had previously been recovered from Parana. Now, researchers believe there may be more unique discoveries to be made in the layers of ancient desert.
“It is a rich but little explored area that would surely bring great news to the world of paleontology,” co-author Neurides Martins of the Paleontology Museum of Cruzeiro do Oeste tells AFP.