In January 1912, German geophysicist Alfred Wegener proposed an concept the scientific world thought was wack.
After scrutinizing similar-looking fossils of vegetation and animals on completely different land plenty, he puzzled if maybe the continents had as soon as been joined collectively earlier than in some way separating into a brand new configuration.
His work was roundly scorned, and dismissed as “delirious ravings”. Now, after all, the concept of continental drift is accepted as established science, with many various strains of proof all pointing within the path of Wegener’s supercontinent, now generally known as Pangea.
Paleontologists have simply recognized one other instance that will 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 areas outline one of many final locations dinosaurs might cross between the land plenty freely earlier than the continent of Gondwana – a fraction of Pangea – broke away utterly, 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 decided that when it comes to age, these footprints have been comparable,” says paleontologist Louis Jacobs of Southern Methodist College. “Of their geological and plate tectonic contexts, they have been additionally comparable. When it comes to their shapes, they’re nearly similar.”
The metamorphosis of Earth’s continental configuration was not a one-and-done occasion, however a protracted, ongoing course of that continues to today, with the continents persevering with to slowly transfer across the globe.
We will piece collectively previous preparations by options such because the shapes of and alignments of shorelines, matching mountain ranges and rock sorts which are comparable throughout continents, and even fossils which are comparable to one another as Jacobs and his crew have performed right here.
From strains of proof similar to 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 beneath, hardening into a brand new crust that will type the ground of the Atlantic Ocean. As the 2 new continents continued to separate, the factors at which animals might transfer between them grew to become smaller and fewer.
“One of many youngest and narrowest geological connections between Africa and South America was the elbow of northeastern Brazil nestled towards what’s now the coast of Cameroon alongside the Gulf of Guinea,” Jacobs explains. “The 2 continents have been steady alongside that slender stretch, in order that animals on both facet of that connection might probably transfer throughout 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 are able to extrapolate that different, maybe much less heavy-footed animals might observe comparable paths.
This, the crew says, implies that the 2 locations fashioned what they’ve named the Borborema-Cameroon dinosaur dispersal hall – one of many final locations animals might transfer between the continents earlier than they break up aside utterly.
“This examine locations dinosaur tracks in a context to elucidate an applicable path of biogeographical change between what would quickly (geologically) turn out to be separate continents,” the researchers write of their paper.
“Now we have tracked dinosaur footprints from the time they have been impressed in mud alongside rivers and lakes over 120 million years in the past, in localities initially contiguous and on a single landmass however some 1000 kilometers aside. Right now, these websites of fossil preservation are on two continents separated by 6000 kilometers and an ocean.”
The paper, titled “The Early Cretaceous Borborema-Cameroon Dinosaur Dispersal Hall”, 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 won’t be made accessible on-line.
