Matching sets of dinosaur footprints found on opposite sides of the Atlantic Ocean

Matching sets of footprints discovered in Africa and South America reveal that dinosaurs once traveled along a type of highway 120 million years ago before the two continents split apart, according to new research. Paleontologists have found more than 260 dinosaur footprints from the Early Cretaceous Period in Brazil and Cameroon, now more than 3,700 miles (6,000 kilometers) apart on opposite sides of the Atlantic Ocean. The footprints are similar in age, shape and geologic context. Most of the fossilized prints were created by three-toed theropod dinosaurs, while a few likely belonged to lumbering four-legged sauropods with long necks and tails or ornithischians. The trackways tell a story of how the movements of massive landmasses created ideal conditions for dinosaurs before supercontinents broke apart into the seven continents we know today. The footprints were preserved in mud and silt along ancient rivers and lakes that once existed on the supercontinent Gondwana, which broke away from the larger landmass of Pangea. Africa and South America began to pull apart from each other about 140 million years ago. The separation created rifts in Earth’s crust, and as the tectonic plates beneath South America and Africa drifted away, magma in Earth’s mantle created new oceanic crust. Over time, the South Atlantic Ocean filled the space between the two continents. But before this gradual change took place, different types of basins formed as Earth’s surface pulled apart. Rivers fed into the basins, forming lakes. Within both basins, the researchers found dinosaur tracks, ancient river and lake sediments, and fossilized pollen. While dinosaur fossils can yield unique insights about the types of animals that roamed the planet millions of years ago, their footprints provide other windows into the past. It’s difficult to tell the specific species of dinosaurs that traveled along the basins, but they represent a larger portrait of the ancient climate and how different types of animals thrived in the environment that the continental rifting created. At the time, rainfall levels helped create a tropical rainforest-type environment with abundant vegetation. Animals came to the basins from both present-day Africa and South America, causing their populations to mix. Later, once the continents drifted apart, this disruption likely caused a break in genetic continuity, a key driver of evolution. The dinosaur tracks in Cameroon were first discovered in the late 1980s. As research into the basins in Africa and South America has continued in the following decades, scientists have reviewed existing and new fieldwork and research to analyze the matching aspects. “We wanted to put new and evolving evidence together to tell a story more specifically of where and why and when dispersals between the continents happened,” said one of the researchers.