Scientists discover similar dinosaur footprints on opposite sides of the Atlantic

In an undated photo provided by Ismar de Souza Carvalho, ornithopod tracks are preserved in floodplain deposits at Passagem das Pedra, in Picos, Brazil. Researchers discovered more than 260 footprints more than 3,700 miles apart in Brazil and Cameroon that were preserved in mud and silt. (Ismar de Souza Carvalho via The New York Times)

By Alexandra E. Petri

They may be an ocean apart, but dinosaur footprints found in South America and Africa are so similar that their discovery suggests dinosaurs may have roamed a narrow corridor that connected the two continents before they split.

Researchers found more than 260 footprints more than 3,700 miles apart in Brazil and Cameroon that were preserved in mud and silt where ancient rivers and lakes once stood, according to a study published last Monday by the New Mexico Museum of Natural History and Science. The tracks were made 120 million years ago, when Africa and South America were still connected as part of a supercontinent called Gondwana, the researchers found.

According to the study, the Borborema Plateau in northeastern Brazil and the Koum Basin in northern Cameroon both contain similar geological structures that preserved dinosaur prints.

The footprints discovered in those areas were similar in age, shape and geological context, said Dr. Louis L. Jacobs, a paleontologist at Southern Methodist University in Texas and the study’s lead author.

It is not surprising to make similar discoveries in regions that were once connected, Jacobs said, but the dinosaur tracks help us understand the geologic history of a region that broke apart millions of years ago.

The paper shows a “specific place at a specific time with specific climatic conditions and environmental conditions” that can help demonstrate how animals may have moved across the stretch of land between Cameroon and Brazil before Gondwana broke apart, Jacobs said.

Jacobs said his research began in Cameroon in the late 1980s, when he and a team of French and Cameroonian researchers discovered dinosaur bones, fossilized mammal bones and dinosaur footprints. He revisited the findings recently when the New Mexico Museum of Natural History and Science wanted to publish a volume dedicated to Martin Lockley, a paleontologist who died in November after a career studying dinosaur tracks and footprints.

Jacobs worked with an international team to determine the age of footprints he’d previously found in Cameroon by studying the rocks they were preserved in. They then looked at records of dinosaur tracks in Brazil, where the continents were once joined and where Jacobs knew there were tracks.

Most of the footprints were created by three-toed theropod carnivores, which tended to be bipedal. Some were also made by long-neck sauropods or ornithischians, a diverse superfamily of herbivores, according to Diana P. Vineyard, a research associate at Southern Methodist University and co-author of the study.

“The geology started looking very similar,” Jacobs said. “Even the structures that showed how the continents broke apart were continuous right across from Brazil into Cameroon.”

The team also looked at a paleogeographic model of Earth, which included topography and river valleys present at the time, and a climate model for 120 million years ago. The sediments also contained fossil pollen that was about 120 million years old or older, according to the paper.

The dinosaur tracks help tell the story of our present-day world, Jacobs said.

“Dinosaur tracks tell you things bones won’t,” he said. “It shows how they moved, where they moved, whether they moved alone or with others. It’s a different way of looking at the past because there is different information contained in the footprints.”

Emese Bordy, a sedimentologist at the University of Cape Town who specializes in southern Gondwana’s paleoenvironments and who was not involved in the research, said in an email it was not “unexpected to find” the footprints left behind by theropods dating to this time period.

“While the presence of these types of fossils in this location is not surprising, the fact that they have been preserved at all remains extraordinary,” said Bordy, who in 2020 published a study about dozens of footprints left by dinosaurs and other creatures in what is now South Africa before Gondwana broke up.

“All geological work is interconnected, and by refining the geological background of this remote area in Africa, the authors help solve a puzzle piece of African Earth history, which contributes to our understanding of Gondwana’s and ultimately the Earth’s history,” Bordy wrote.