Continental drift theory was unveiled in 1912 and was met with hilarity. Alfred Wegener (1880-1930), who deduced why the continents look like pieces of a puzzle that fit together (because they were), died without the gratification of acceptance. It would only be in the 1960s that multiple lines of evidence were put together and the grand theory of plate tectonics, now accepted as dogma, would emerge.
Now an international team of scientists led by paleontologist Louis Jacobs of the Southern Methodist University is reporting on matching sets of Early Cretaceous dinosaur footprints in Brazil and Cameroon. More than 260 footprints show that 120 million years ago, dinosaurs were strolling around both continents – when they were one, or the supercontinent called Gondwana, which split off from the earlier supercontinent Pangaea. The track sites, made in wetlands lakeshores 120 million years ago, are now separated by more than 6,000 kilometers (3,700 miles).
Most of the dinosaur fossils were created by three-toed theropod terrestrial dinosaurs, the group that would bring us tiny little predators and the great T-rex types and that would produce the birds we know and love to eat. Other prints the team studied were likely made by ornithischians, the "bird-hipped" dinosaurs that did not produce the birds, and some were probably made by sauropods, the giants with long necks, according to coauthor Diana Vineyard. These sets of tracks the team studied in Brazil and Cameroon are far from the first concrete evidence that the continents were once a concentrated land mass, but it's a stunning example.
Other fossil discoveries in both the Americas and Africa, also supporting the plate tectonics theory, include the freshwater lizard Mesosaurus, which has been found in South Africa, Uruguay and Brazil. Duckbill dinosaurs dwelled in the Rocky Mountains, Appalachia, Chile, Europe and Morocco among other places. "We determined that in terms of age, these footprints were similar," Jacobs said in a statement.
"In their geological and plate tectonic contexts, they were also similar. In terms of their shapes, they are almost identical." When these trackways were laid down, approximately 120 million years ago, in fact Gondwana was already breaking up.
Jacobs surmises that the animals lived where "the elbow" of northeastern Brazil was still attached to Africa at the Cameroonian coast. In Brazil the footprints were found at the Borborema region in the northeast and in Cameroon, in the Koum Basin. Dating the age of dinosaur bones is tricky enough, let alone footprints.
They're too old for radiocarbon dating to apply. The estimated date of the prints is based on fossil pollen , the team claims. Flowering plants, once thought to be a recent wrinkle of only about the last 90 million years, are now thought to be at least a quarter-billion years old.
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