In January 1912, German geophysicist Alfred Wegener proposed an concept the scientific world thought was wack.
After scrutinizing similar-looking fossils of crops and animals on totally different land plenty, he puzzled if maybe the continents had as soon as been joined collectively earlier than one way or the other separating into a brand new configuration.
His work was roundly scorned, and dismissed as “delirious ravings”. Now, in fact, the thought of continental drift is accepted as established science, with many alternative strains of proof all pointing within the route of Wegener’s supercontinent, now often called Pangea.
Paleontologists have simply recognized one other instance that might have delighted the geophysicist; nearly similar units of dinosaur footprints have been present in Cameroon in Central Africa and in Brazil in South America, separated by a distance of greater than 6,000 kilometers (about 3,700 miles).
These two places outline one of many final locations dinosaurs may cross between the land plenty freely earlier than the continent of Gondwana – a fraction of Pangea – broke away fully, some 120 million years in the past.
Collectively, there are greater than 260 footprints, stamped into the mud of riverbanks by ornithopod, sauropod, and theropod dinosaurs throughout what may need been the final land bridge connecting Africa to South America.
“We determined that in terms of age, these footprints were similar,” says paleontologist Louis Jacobs of Southern Methodist College. “In their geological and plate tectonic contexts, they were also similar. In terms of their shapes, they are almost identical.”
The metamorphosis of Earth’s continental configuration was not a one-and-done occasion, however an extended, ongoing course of that continues to at the present time, with the continents persevering with to slowly transfer across the globe.
We will piece collectively previous preparations by taking a look at options such because the shapes of and alignments of shorelines, matching mountain ranges and rock varieties which might be comparable throughout continents, and even fossils which might be comparable to one another as Jacobs and his group have performed right here.
From strains of proof reminiscent of these, scientists have decided that Africa and South America began to separate other than one another round 140 million years in the past. Rifts fashioned within the crust, and a spot between the 2 items of Gondwana began to widen. In these cracks, magma flowed up from under, hardening into a brand new crust that might kind the ground of the Atlantic Ocean. As the 2 new continents continued to separate, the factors at which animals may transfer between them grew to become smaller and fewer.
“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 explains. “The two continents were continuous along that narrow stretch, so that animals on either side of that connection could potentially move across it.”
To seek out these factors of passage, he and his colleagues made a cautious examine of the printed literature. They reconstructed the sundering of the continents, making the case for a connection level between Borborema in Brazil and Cameroon. Then, they studied the dinosaur tracks in each areas, evaluating them, and discovering that they matched.
Due to this connection, we will extrapolate that different, maybe much less heavy-footed animals may comply with comparable paths.
This, the group says, signifies that the 2 locations fashioned what they’ve named the Borborema-Cameroon dinosaur dispersal hall – one of many final locations animals may transfer between the continents earlier than they cut up aside fully.
“This study places dinosaur tracks in a context to elucidate an appropriate path of biogeographical exchange between what would soon (geologically) become separate continents,” the researchers write of their paper.
“We have tracked dinosaur footprints from the time they were impressed in mud along rivers and lakes over 120 million years ago, in localities originally contiguous and on a single landmass but some 1000 kilometers apart. Today, these sites of fossil preservation are on two continents separated by 6000 kilometers and an ocean.”
The paper, titled “The Early Cretaceous Borborema-Cameroon Dinosaur Dispersal Corridor”, has been printed within the New Mexico Museum of Pure Historical past and Science Bulletin, as a tribute to late paleontologist Martin Lockley, who was an avid scholar of dinosaur tracks. This paper is not going to be made out there on-line.
