Tens of millions of years ago, South America and Africa were part of the same landmass, an ancient supercontinent called Gondwana. At some point, the two continents began to drift apart until only a thin strip of land remained above, holding them together. A team of scientists in a new study argues that matching dinosaur tracks found in what are now Brazil and Cameroon were left along this narrow passage 120 million years ago, before the continents split apart.
“They were connected only by a land bridge, and that land bridge is the corridor we’re talking about,” said Louis Jacobs, professor emeritus of earth sciences at Southern Methodist University.
Jacobs led an international team of scientists who analyzed more than 260 tracks left by early Cretaceous dinosaurs, mostly carnivorous three-toed theropods, but also possibly some sauropods or ornithischian dinosaurs.
They found that prehistoric footprints in both countries were strikingly similar, despite being 3,700 miles (5,954,573 km) apart.
The dinosaur tracks imprinted in sedimentary rocks along ancient rivers and lakes were all of the same age and shape and had distinct geological features. Scientists have found evidence of major geological events in Brazil’s Borborema region and Cameroon’s Qom Basin that led to the separation of the two continents.
Researchers analyzed theropod tracks in Brazil (left) and Cameroon (right). Southern Methodist University
The researchers say the evidence suggests that the ancient area that connected the two continents had rivers and lakes that could have supported an ecosystem that included plants, herbivores and carnivores.
It’s not surprising, Jacobs says, that South America and Africa once looked like puzzle pieces, and that animals have likely crossed that invisible boundary throughout history.
“But what’s amazing is that you can actually narrow down the time and place to the end of the connection between the two continents and say that’s how dinosaurs could have moved,” he said.
The study was published by the New Mexico Museum of Natural History and Science.
The dinosaur tracks in Cameroon were first identified in the 1980s. But Jacobs and other researchers recently took a fresh look at them after the death of a colleague, the late paleontologist Martin Lockley, using scientific methods that were not available at the time.
“I hadn’t thought about the dinosaur tracks in Cameroon for decades, and then when I went back to them and started looking at them and asking what they were trying to tell us, I was so surprised to see how much we’ve learned over the decades and how much the story has improved,” Jacobs said.