A newly published study in Science announces the discovery of Spinosaurus mirabilis, a previously unknown species of spinosaurid dinosaur uncovered in Niger. The fossils were excavated in a remote region of the central Sahara by a 20 member research team led by Paul Sereno, PhD, Professor of Organismal Biology and Anatomy at the University of Chicago. The find adds significant new evidence to the final phase of spinosaurid evolution.
One of the most remarkable features of S. mirabilis is its enormous, scimitar shaped crest. When paleontologists first spotted the crest and several jaw fragments on the desert surface in November 2019, they did not immediately realize what they had found. It was only after returning in 2022 with a larger team and uncovering two more crests that the researchers understood they were dealing with a new species.
The texture of the crest and the network of blood vessel channels inside it indicate that it was covered in keratin, the same material found in human fingernails. Researchers believe the crest was brightly colored during the dinosaur’s lifetime and arched upward like a curved blade, likely serving as a dramatic display structure.
The skull also reveals tightly interlocking upper and lower teeth that formed an effective trap for slippery prey. In this arrangement, the lower teeth extend outward between the upper teeth when the jaws close. This adaptation appears repeatedly in the fossil record among fish eating animals, including aquatic ichthyosaurs, semi aquatic crocodile and flying pterosaurs. Among dinosaurs, however, this feature distinguishes Spinosaurus and its closest relatives.
“This find was so sudden and amazing, it was really emotional for our team,” Sereno said. “I’ll forever cherish the moment in camp when we crowded around a laptop to look at the new species for the first time, after one member of our team generated 3D digital models of the bones we found to assemble the skull — on solar power in the middle of the Sahara. That’s when the significance of the discovery really registered.”
Inland Habitat Challenges Aquatic Dinosaur Theory
Until now, most spinosaurid fossils had been recovered from coastal deposits close to ancient shorelines. That pattern led some researchers to suggest these fish eating theropods may have been fully aquatic predators that hunted underwater.
The newly identified fossil site in Niger tells a different story. The remains were found 500-1000 km from the nearest ancient marine shoreline. Nearby were partial skeletons of long necked dinosaurs preserved in river sediments, pointing to a forested inland environment crisscrossed by waterways.
“I envision this dinosaur as a kind of ‘hell heron’ that had no problem wading on its sturdy legs into two meters of water but probably spent most of its time stalking shallower traps for the many large fish of the day,” Sereno said.
A 70 Year Old Clue Leads to the Sahara
The expedition that led to this discovery began with a brief note in a 1950s monograph. In it, a French geologist mentioned a single sabre shaped fossil tooth resembling those of the massive predator Carcharodontosaurus, originally found in Egypt’s Western Desert in the early 1900s.
“No one had been back to that tooth site in over 70 years,” Sereno said. “It was an adventure and a half wandering into the sand seas to search for this locale and then find an even more remote fossil area with the new species. Now all of the young scholars who joined me are co-authors on the report gracing the cover of Science.”
During their search, the team encountered a Tuareg man who offered to guide them on his motorbike deep into the Sahara, where he had seen enormous fossil bones. After nearly a full day of travel and uncertainty, he led them to a fossil rich area. With limited time before heading back to camp, the researchers collected teeth and jaw fragments belonging to the new Spinosaurus species.
“I was attracted to the Sahara like a magnet once I set foot there 30 years ago,” Sereno said. “There’s nowhere else like it. It’s as beautiful as it is daunting.” After excavating more than 100 tons of fossils over the years, he added, “If you can brave the elements and are willing to go after the unknown, you might just uncover a lost world.”
Expanding Niger’s Paleontological Legacy
The discovery strengthens Niger’s reputation as a major site for paleontology and archaeology. Sereno has long worked in the country and has led the creation of the world’s first zero energy museum, the Museum of the River, located on an island in the center of Niamey, Niger’s capital. The museum will display the country’s remarkable fossil heritage, including this newly identified spinosaur, along with artifacts from stone age cultures that lived in a once lush Green Sahara.
“The local people we work with are my lifelong friends, now including the man who led us to Jenguebi and the astonishing spinosaur. They understand the importance of what we’re doing together — for science and for their country,” Sereno said.
Bringing Spinosaurus mirabilis Back to Life
At the University of Chicago’s South Side Fossil Lab in Washington Park, the team carefully prepared and CT scanned the fossils to create a digital reconstruction of the skull for the scientific report. Using that model, Sereno collaborated with paleoartist Dani Navarro in Madrid to produce a dramatic scene showing the new species competing over a coelacanth carcass. Navarro also built a detailed 3D physical model by layering muscle and skin over a skeletal framework.
Additional paleoartists in Chicago (Jonathan Metzger) and Italy (Davide la Torre) animated Navarro’s model, recreating the scene featured on the cover of Science. Advances in software, imaging tools, cameras, and drones have transformed how paleontologists document and visualize discoveries in both fieldwork and laboratory settings.
Inspiring the Next Generation
As part of the reconstruction process, the team produced a replica of the skull and a colorful, touchable version of the curved crest.
Beginning March 1, following publication of the Science paper, these replicas will join Sereno’s Dinosaur Expedition exhibit at the Chicago Children’s Museum. Young visitors will be among the first to see and handle representations of this newly discovered dinosaur.
“Letting kids feel the excitement of new discoveries — that’s key to ensuring the next generation of scientists who will discover many more things about our precious planet worth preserving,” Sereno said.
