Around 95 million years ago, a Spinosaurus dinosaur, distinguished by a tall, blade-like crest and a large sail on its back, roamed what is now Niger, according to a new study. Researchers have identified this as a new species, tentatively named Spinosaurus mirabilis (“astonishing Spinosaurus” in Latin).
The discovery, published , in the journal Science, suggests this dinosaur lived far inland, in a riverine environment. This finding may contribute to resolving a long-standing debate about whether Spinosaurus and its relatives were primarily aquatic animals.
“There’s just no way that you’re going to find… essentially an aquatic animal hundreds of miles from the shoreline, buried… right in a river deposit,” explained study first author Paul Sereno, a paleontologist at the University of Chicago.
The discovery was facilitated by a Tuareg guide, a member of the nomadic population inhabiting the Sahara Desert, who led the research team to the remote site in 2019. The fossils presented an unusual characteristic: their black coloration, attributed to an increased concentration of phosphate in the bone. Sereno noted that in his 25 years of fieldwork, he had never encountered fossils of this color in the Sahara Desert.
The Crest Points to a New Species
Initially, the team struggled to understand how certain bones fit within the overall skeletal structure. “We didn’t recognize the crest,” Sereno said. “It was just so weird [and] asymmetrical.”
The puzzle was solved in 2022 when a larger team uncovered a skull with a partial crest attached. Subsequent CT scans of the fossil revealed numerous fossilized blood vessels within the crest, and surface textures suggesting it was covered in a keratin sheath, potentially reaching a height of 20 inches (0.5 meters). Researchers believe this crest served a decorative purpose, possibly aiding in species recognition during mating or establishing dominance along riverbanks.
The researchers describe the crest as the tallest known in any meat-eating dinosaur.
So… Was Spinosaurus a Swimmer?
Recent research has proposed that Spinosaurus – encompassing S. Mirabilis and related species like S. Aegyptiacus – actively hunted prey underwater, exhibiting characteristics of a marine hunter. The team noted the dinosaur’s teeth, with protruding lower jaw teeth fitting between the sharp teeth of the upper jaw, are consistent with a fish-eating diet.
However, the location of the fossil – found alongside two long-necked sauropods in a riverbed – and the dinosaur’s overall body shape lead Sereno to propose a different lifestyle. He envisions Spinosaurus as a “hell heron,” capable of wading in water up to two meters (6.5 feet) deep, but primarily stalking prey in shallower environments.
Sereno also pointed out that the large sail on Spinosaurus’ back would have added significant weight, potentially hindering its ability to swim effectively. “It’s sacrificing… aspects of its agility for this, but it’s an important feature,” he said.
The researchers compared the body shape of S. Mirabilis to those of modern and extinct predators, placing it between semiaquatic waders like herons and aquatic divers like penguins.
“It shows the process of science evaluating evidence and new evidence appearing,” Sereno added.
C. Sereno, P. C. S., Vidal, D., P. Myhrvold, N., Johnson-Ransom, E., Ciudad Real, M., Baumgart, S. L., Sánchez Fontela, N., L. Green, T., T. Saitta, E., Adamou, B., Bop, L., Keillor, T. M., Fitzgerald, E. C., Dutheil, D. B., Laroche, R. A. S., Demers-Potvin, A. V., Simarro, Á., Gascó-Lluna, F., . . . Ramezani, J. (2026). Scimitar-crested Spinosaurus species from the Sahara caps stepwise spinosaurid radiation. Science, 391(1), eadx5486. https://doi.org/10.1126/science.adx5486
