A pair of dinosaur discoveries is shaking up scientific understanding of when South America and Africa split into separate continents.
The discovery of one African dinosaur fossil in particular indicates that a land bridge may have connected the continents 95 million years ago, 25 millions years after they were thought to have parted.
Found in the Sahara desert and dubbed Rugops (Roo-gops) primus, meaning ”first wrinkle face,” the 30-foot-long carnivore resembles similar fossils found in India and South America.
Earth’s continents regularly drift apart and pull together in roughly 600-million-year intervals, a phenomenon known as plate tectonics. The Asian and South American continents, once joined, were slowly drifting apart during the age of the dinosaurs, which ended 65 million years ago.
Scientists have long believed that the continents of Africa and South America split apart for good 120 million years ago. But Rugops’ existence in Africa years later indicates that the continent was still connected in some way to South America, says University of Chicago paleontologist Paul Sereno, a National Geographic explorer-in-residence who led the discovery team.
”One mystery had been how southern dinosaurs got across separated continents. There’s clear evidence of dispersal, which suggests a land bridge,” Sereno says.
Rugops had a short, round snout and small, delicate teeth, typical of carnivorous dinosaurs called abelisaurids. Sereno says the creature likely scavenged the kills of other carnivores or simply beat them to herbivore remains, given its skull’s shape. Other predators had thicker skulls and longer, slashing teeth, suggesting Rugops played a different role in the ancient world.
The team also uncovered fossils of a second dinosaur species, named Spinostropheus (Spine-o-stro-phee-us) gautieri, also an abelisaurid dinosaur. They emerged in Niger in 135-million-year-old rocks. Both finds are described in today’s Proceedings of the Royal Society of London, Biological Sciences journal.
Paleontologist Thomas Holtz Jr. of the University of Maryland in College Park says dinosaur scientists and geologists will be interested in what the fossils show about how the ancient continents split and how the abelisaurids related to one another across continents.
Fossil traces of Spinostropheus had been discovered over the last few decades, but Sereno’s team first recognized the new species.
An oddity of Rugops is that its skull was probably covered in a tough layer of keratin, the material in fingernails and bird beaks.
Sereno and other paleontologists have suggested that many dinosaurs — like triceratops, the wickedly horned herbivore found in every grade-schooler’s dinosaur diorama — may also have been armored in keratin, rather than the reptilian scales long considered standard for these oversized creatures. The shell, like a vulture’s beak, probably helped Rugops rip at carrion, Sereno says.
Visitors to Chicago’s Garfield Park Conservatory can see the fossils as part of an exhibition of African dinosaurs until Sept. 6.
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