A groundbreaking study has revealed a number of nearly identical early detection methods. chalk Dinosaur footprints on two different continents illustrate a prehistoric connection between South America and Africa.
These finds provide compelling evidence of a narrow land bridge that allowed dinosaurs to migrate between these continents before they drifted apart to form the South Atlantic.
Discovery of dinosaur footprints connects continents
An international team of researchers led by paleontologist Louis L. Jacobs of Southern Methodist University (SMU) has found matching footprints of Lower Cretaceous dinosaurs on two different continents.
More than 260 footprints have been discovered in Brazil and Cameroon, showing where land-dwelling dinosaurs were last able to migrate freely between South America and Africa millions of years ago, before the two continents broke apart.
Basin preserved in the floodplain deposits of the Lower Cretaceous. Photo credit: Ismar de Souza Carvalho
“We found that these footprints were similar in age,” Jacobs said. “They were also similar in their geological and plate tectonic context. In terms of their shapes, they are almost identical.”
The footprints, imprinted in mud and silt along ancient rivers and lakes, were found more than 6,000 kilometers apart. Dinosaurs left the tracks 120 million years ago on a single supercontinent called Gondwana, which split off from the larger landmass Pangaea, Jacobs said.
Narrow connection facilitated dinosaur migration
“One of the most recent and closest geological connections between Africa and South America was the arc in northeastern Brazil that hugged what is now the coast of Cameroon on the Gulf of Guinea,” Jacobs explained. “The two continents overlapped along this narrow stretch, so animals on either side of this connection could potentially cross it.”
Most dinosaur fossils were created by three-toed theropod dinosaurs, but some probably came from sauropods or ornithischians, says Diana P. Vineyard, a research associate at SMU and co-author of the study.
Northeast Brazil. Photo credit: Ismar de Souza Carvalho
Other co-authors of the study were Lawrence J. Flynn in the Department of Human Evolutionary Biology at Harvard University, Christopher R. Scotese in the Department of Earth and Planetary Sciences at Northwestern University and Ismar de Souza Carvalho at the Federal University of Rio de Janeiro and the Centro de Geociências.
The study was published by the New Mexico Museum of Natural History & Science as a tribute to the late paleontologist Martin Lockley, who devoted much of his career to studying dinosaur tracks and footprints.
Dinosaur footprints tell the whole story
Africa and South America began to separate about 140 million years ago, opening cracks in the Earth’s crust, called rifts, along pre-existing weak spots. As the tectonic plates beneath South America and Africa moved apart, magma from the Earth’s mantle rose to the surface, forming new oceanic crust as the continents moved apart. And eventually, the South Atlantic Ocean filled the void between these two newly formed continents.
Signs of some of these major events were clearly visible at both sites where the dinosaur tracks were found – the Borborema region in northeastern Brazil and the Koum Basin in northern Cameroon. Both areas contain half-graben basins – geological structures created during the splitting of the Earth’s crust as faults formed – that contain ancient river and lake sediments. In addition to dinosaur tracks, these sediments also contain fossil pollen that suggests they are 120 million years old.
Before the continental connection between Africa and South America was severed, “rivers flowed and lakes formed in the basins,” Jacobs said. “Plants fed the herbivores and supported a food chain. Muddy deposits left by the rivers and lakes contain footprints of dinosaurs, including carnivores. This shows that 120 million years ago these river valleys provided special pathways for life to move across the continents.”
