Matching sets of 120-million-year-old dinosaur tracks found on two continents provide new insights into Earth’s ancient geography. Researchers discovered over 260 footprints in Brazil and Cameroon, shedding light on the last period when land-dwelling dinosaurs could freely roam between South America and Africa.
A team of international scientists, led by Southern Methodist University (SMU) paleontologist Louis L. Jacobs, uncovered these remarkable fossils. The footprints were found more than 3,700 miles apart, yet they tell a unified story of life on the ancient supercontinent Gondwana.
Uncovering Ancient Connections Through Fossil Evidence
The dinosaur tracks were impressed into mud and silt along prehistoric rivers and lakes. They date back to the Early Cretaceous period, about 120 million years ago. At that time, South America and Africa were still joined as part of Gondwana, which had separated from the larger landmass of Pangea.
“One of the youngest and narrowest geological connections between Africa and South America was the elbow of northeastern Brazil nestled against what is now the coast of Cameroon along the Gulf of Guinea,” Jacobs explained. “The two continents were continuous along that narrow stretch, so that animals on either side of that connection could potentially move across it.”
Most of the tracks were made by three-toed theropod dinosaurs, with a few likely created by sauropods or ornithischians, according to Diana P. Vineyard, a research associate at SMU and co-author of the study.
The similarity between the footprints found on both continents is striking. “We determined that in terms of age, these footprints were similar,” Jacobs said. “In their geological and plate tectonic contexts, they were also similar. In terms of their shapes, they are almost identical.”
Tracing the Split of Ancient Continents
The research provides valuable insights into the process of continental drift and the formation of the South Atlantic Ocean. Africa and South America began to separate around 140 million years ago, with rifts opening along pre-existing weaknesses in Earth’s crust.
As tectonic plates moved apart, magma rose from the Earth’s mantle, creating new oceanic crust. Over time, the South Atlantic Ocean filled the widening gap between the two continents.
Evidence of these dramatic geological events was found at both footprint locations – the Borborema region in northeastern Brazil and the Koum Basin in northern Cameroon. Both areas contain half-graben basins, geological structures formed as Earth’s crust pulled apart during rifting.
“Rivers flowed and lakes formed in the basins,” Jacobs explained. “Plants fed the herbivores and supported a food chain. Muddy sediments left by the rivers and lakes contain dinosaur footprints, including those of meat-eaters, documenting that these river valleys could provide specific avenues for life to travel across the continents 120 million years ago.”
Why it matters: This research provides a unique window into Earth’s ancient past, helping us understand how continental drift shaped not only our planet’s geography but also the evolution and distribution of life. By studying these dinosaur footprints, scientists can better reconstruct ancient ecosystems and migration patterns, offering valuable insights into the interconnectedness of life on Earth millions of years ago.
The study, published by the New Mexico Museum of Natural History & Science, is part of a tribute to the late paleontologist Martin Lockley, who dedicated much of his career to studying dinosaur tracks and footprints. It represents a significant contribution to our understanding of Earth’s geological and biological history, demonstrating the power of fossil evidence in unraveling the mysteries of our planet’s past.
