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Paleontologists Paul Sereno and Dan Vidal take notes on a massive hind limb of a new long-necked dinosaur, its femur measuring nearly 2m in length, at the Jenguebi dig site in Niger in November 2022.
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Matthew Irving/Fossil Lab/University of Chicago
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Matthew Irving/Fossil Lab/University of Chicago
A newly discovered species of large dinosaur lived in marshy areas, hunted for fish and had an impressive horn protruding from its skull. It is the first time in over 100 years that scientists have discovered a new species of Spinosaurus dinosaurs, which are large fish-eating predators that first emerged during the Jurassic period more than 140 million years ago. The new species, called Spinosaurus mirabilis, was the length of a school bus and was unearthed in Niger by an international team of scientists led by paleontologists from the University of Chicago. Details of the discovery were published in the journal Science last week.
The authors estimate that Spinosaurus mirabilis lived about 95 million years ago during the Cretaceous period, in a marshy inland area in what is now the central Sahara.
Lead author Paul Sereno compared them to herons, which also hunt for fish in shallow water and have bodies that are well-suited to semi-aquatic living. “I suspect that this animal was fishing largely in about 3 feet of water,” he explained in an email to NPR, although it was large enough to stand in about 6 feet of water without floating. “There were many large fish in the rivers of its day,” Sereno said, including some that measured 9 feet or more in length — good eating for a large predator.
Skull casts of the newly discovered Spinosaurus mirabilis from Niger (top) and its previously discovered cousin Spinosaurus aegyptiacus (bottom) show how the new species has a pronounced horn.
Keith Ladzinski/University of Chicago
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Keith Ladzinski/University of Chicago
The most obvious physical difference between the newly discovered species and its previously discovered cousins is a foot-long curved horn that protrudes from its skull. The authors speculate that the horn, or crest, may have been brightly colored, based on the texture of the fossils, and that the crest may have been used to attract or communicate with other members of the species. The team first discovered one of the crucial crest fossils during a scientific expedition in 2019. They returned in 2022 and discovered more specimens at the same site, which is in a remote stretch of sandy desert in the Sahara.
But the area wasn’t a desert when Spinosaurus was alive. During the mid-Cretaceous period, the site had rivers running through it, although it was hundreds of miles from the nearest ocean. Scientists who study Spinosaurus are particularly interested in how aquatic the massive animals really were. In 2020, paleontologist Nizar Ibrahim told NPR’s daily science podcast Short Wave that bones his team collected in Morocco suggested that a previously identified species of Spinosaurus was a powerful swimmer. “The tail of Spinosaurus is comparable to fully aquatic or largely aquatic animals alive today,” Ibrahim explained. But the new findings complicate that picture, presenting evidence of an animal that may have thrived in relatively shallow waters. “Like blue herons, we imagine it to be a poor swimmer that never dives for its meals,” said Sereno.
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