Matching dinosaur footprints discovered in Africa and South America indicate that dinosaurs roamed freely 120 million years ago, prior to the separation of these two continents.
Paleontologists have found over 260 early Cretaceous dinosaur footprints in Brazil and Cameroon, located over 3,700 miles (6,000 km) apart on opposite shores of the Atlantic Ocean.
Louis L. Jacobs, a paleontologist at Southern Methodist University in Texas and the lead author of a study on these footprints published by the New Mexico Museum of Natural History and Science on Monday, noted that the footprints share similar ages, shapes, and geological contexts.
“Most of the fossilized footprints belong to three-toed theropod dinosaurs, with a few possibly belonging to four-legged lizard-hipped dinosaurs with long necks and tails or ornithischians, which have pelvic structures similar to birds,” said co-author Diana P. Vineyard, a research associate at SMU.
The trails tell us about the movement of massive landmasses, creating ideal conditions for dinosaurs to thrive before the supercontinent split into the seven continents we know today.
Typical theropod footprints from the Koum Basin in northern Cameroon. (Photo: SMU).
Life-Sustaining Basins
The footprints were preserved in mud and silt along ancient rivers and lakes that once existed on the supercontinent Gondwana, which was once part of a larger landmass known as Pangaea, Jacobs explained.
“One of the earliest and narrowest connections between Africa and South America is the ‘elbow’ of northeastern Brazil, located close to the coast of Cameroon along the Gulf of Guinea,” Jacobs noted. “These two continents were along that narrow strip, allowing animal species to move between them.”
Africa and South America began to separate around 140 million years ago, causing cracks in the Earth’s crust. As tectonic plates beneath South America and Africa drifted apart, magma in the Earth’s mantle created new oceanic crust. Over time, the South Atlantic Ocean filled the gap between the two continents.
Red stars in this image mark the routes dinosaurs once traveled when South America and Africa were not yet separated. (Photo: SMU).
Jacobs mentioned that different types of basins formed as the Earth’s surface split apart, with rivers feeding into these basins and creating lakes.
Researchers found evidence of a half-graben basin in the Borborema region of northeastern Brazil and a similar basin in Koum, northern Cameroon.
In both basins, researchers discovered dinosaur traces, ancient river and lake sediments, as well as fossilized pollen.
“The mud sediments left by rivers and lakes contain dinosaur footprints, including those of carnivorous animals, proving that these river valleys could have provided specific pathways for movement across continents 120 million years ago,” Jacobs explained.
The Story from the Footprints
While dinosaur fossils can provide unique insights into the species that existed on our planet millions of years ago, their footprints offer another perspective on the past.
Jacobs stated: “Dinosaur footprints are not rare, but unlike the often-seen bone fragments, footprints are evidence of dinosaur behavior, how they walked, ran, or interacted with others, the environments they traversed, the directions they moved in, and where they were during their activities.”
At that time, rainfall created a tropical rainforest environment with rich vegetation. Animals migrated to the basins from both present-day Africa and South America, leading to a blending of their populations.
The dinosaur footprints in Cameroon were first discovered in the late 1980s, and Jacobs reported on them at the first international symposium on dinosaur tracks and traces, organized by paleontologist Martin Lockley in 1986.
