Fossils point to a giant fish hunter that likely waded, not swam, in ancient rivers.
CHICAGO, IL — Fossils pulled from a hard-to-reach corner of Niger’s Sahara Desert have been identified as a new species of Spinosaurus, a sail-backed predator made famous in movies and museum halls. Scientists said the dinosaur lived about 95 million years ago and carried a tall, curved head crest like a sword.
The find matters because Spinosaurus sits at the center of a long argument about how some dinosaurs lived around water. For years, some researchers have suggested Spinosaurus could have been a powerful swimmer, diving after prey. The newly described species, found far inland in rocks tied to ancient rivers, adds weight to a different picture: a giant hunter built to stalk the shallows and snap up fish. The study also expands a genus that has been hard to pin down, in part because key early fossils were lost long ago, leaving gaps that new material can finally help fill.
The new species has been named Spinosaurus mirabilis, meaning “astonishing,” and was described in a study published this week in the journal Science. Its most striking feature is a tall, blade-shaped bony crest that rose from the top of its skull and likely extended farther in life with a covering of keratin, the same material found in horns and beaks. University of Chicago paleontologist Paul Sereno, the study’s lead author, said the animal would have prowled the edges of rivers and wetlands, more like a wading bird than a sleek swimmer. “It’s about love and life,” Sereno said, describing the crest as a likely display structure used to attract mates and compete with rivals.
The path to the discovery stretched across decades and started with a thin clue in an old scientific record. Sereno has described noticing a brief entry about a dinosaur tooth reported from Niger many years ago, then realizing that no one had returned to the site for generations. After earlier attempts fell short, his team went back into the region and searched again, using modern tools like GPS and drones to relocate places that had slipped out of the scientific map. The turning point came when a local Tuareg man approached the camp and said he knew where large bones could be found, directing the team toward an even more remote area called Jenguebi. In 2022, the expedition set out from the city of Agadez in a convoy and drove off-road for days through dunes and exposed rock, often getting stuck in the sand before reaching fossil-rich outcrops surrounded by a sea of dunes.
At Jenguebi, the team uncovered parts of three skulls along with additional bones that matched a spinosaurid, a group known for crocodile-like snouts and a taste for fish. The crest bones were so unusual that, at first, the scientists did not know what they were looking at. Back in the lab, the researchers used scans and detailed comparisons to piece together what the skull would have looked like. They concluded the bones belonged to a previously unknown Spinosaurus species rather than a variation of a known one. Sereno called the trip that produced the key material an unmatched undertaking in the desert, and he has described it as the kind of expedition that few teams can mount because of the distance, the terrain and the need to move large amounts of equipment and fossil material safely across a vast, sparsely populated region.
The new dinosaur would have cut a dramatic shape along the waterways of ancient Africa. Researchers said it had an elongated snout, a set of large, conical teeth designed for gripping slippery prey, and nostrils positioned farther back than in many other dinosaurs, a placement that could allow most of the snout to be submerged while still breathing. Its mouth also shows a tight fit between upper and lower teeth, like interlocking fingers, which helps prevent fish from wriggling free. Daniel Vidal, a study co-author, described the teeth as forming a kind of “fish trap,” a specialization that points strongly toward a diet heavy in fish rather than other dinosaurs. The animal also carried the signature Spinosaurus sail along its back, formed by long spines, and had long hind limbs that fit with the idea of a sturdy wader.
Scientists offered estimates of its size based on the available bones and comparisons with close relatives. They said the species could have reached about 40 feet long and weighed roughly 5 to 7 tons, placing it among the largest meat-eating dinosaurs known. At the same time, some researchers cautioned that many of the newly described specimens may not represent fully grown adults, which adds uncertainty to final measurements. Even so, the team said the animal was clearly massive, and its skull structure shows it was built for powerful bites aimed at fish. The crest itself, about 20 inches tall in bone, appears too delicate to have served as a weapon, making display and recognition the leading explanations. Sereno suggested the crest and sail could have signaled dominance in feeding areas, especially in shallow spots where fish gathered.
The location of the fossils is one of the biggest reasons the discovery is reshaping the story of Spinosaurus. Earlier Spinosaurus finds have often been tied to North African sites closer to ancient coastlines and marine-influenced deposits, which helped fuel the idea of an animal adapted to open-water swimming. Spinosaurus mirabilis was found far inland, hundreds of miles from what would have been the nearest shoreline at the time, in rocks linked to an ancient river system. Researchers said that setting, combined with the anatomy they reconstructed, points toward a predator that hunted by stalking and wading rather than chasing prey underwater. Sereno said the new fossil evidence undercuts the strongest version of the “fully aquatic” argument, calling it a decisive blow to the view that Spinosaurus was built to be a marine pursuit hunter.
The new paper also adds to a long and sometimes frustrating history of Spinosaurus research. The first named species, Spinosaurus aegyptiacus, was described in 1915 from fossils found in Egypt. Those early fossils later became unavailable for study after they were destroyed during World War II, leaving scientists to rely on descriptions, drawings and later discoveries to reconstruct what the animal looked like. Over time, new spinosaurid fossils from Morocco and other parts of North Africa helped rebuild the picture, but debates remained about how the dinosaur moved, where it hunted, and how much of its life it spent in water. The Sahara itself adds another layer of confusion because it was not always a vast desert. During the Cretaceous, the region included networks of rivers and wetlands that supported forests and a wide range of animals, meaning fossils found in today’s dunes can represent a very different world.
The Niger sites connected to the new species have drawn scientific interest before. Western researchers have known of fossil-rich areas in the region since the 1950s, when geologists searching for uranium found large bones emerging from the sand at a place called Gadoufaoua. Expeditions there and nearby areas have turned up a mix of ancient life, including large plant-eating dinosaurs and giant crocodile-like reptiles. The Jenguebi area, where Spinosaurus mirabilis was identified, also includes fossils from other large dinosaurs and fish, painting a picture of a busy river ecosystem where big predators could thrive. That context helps explain why a specialized fish hunter might grow so large: the waterways likely held sizable prey, and the wetlands offered many places to hunt, hide and compete.
Outside experts said the new species is important but also highlights how much remains unknown. Paleontologist David Hone of Queen Mary University of London, who was not part of the research team, said the fossils confirm ideas that Spinosaurus lived around water and had a crest, while showing that this newly named species had a much bigger one and lived in a different setting than where Spinosaurus fossils are often found. Hone said many basic questions about Spinosaurus and its relatives remain open because the group is still known from incomplete material. Researchers involved in the new study said more fieldwork and more preparation of existing fossils will be needed to answer those questions, including how the animals grew, how they moved, and how their bodies balanced the heavy sail and long skull.
For now, the team’s conclusions rest on what the bones show and where they were found. The researchers said the crest likely played a key role in the dinosaur’s social life, while the teeth and snout point to a hunter that fed mainly on fish. The inland river setting, they said, supports a picture of a giant wader that worked the shallows, lunging with its long jaws to seize prey. Sereno has compared the animal to a “hell heron,” a nickname meant to capture both its birdlike hunting style and its huge size. He also said the discovery is part of a broader effort to map Africa’s dinosaur record more clearly, a record that has often been harder to study than those of North America and parts of Asia because of distance, logistics and the challenge of working in remote deserts.
Scientists said additional fossils collected during the Niger expeditions are still being prepared and studied, and more research papers are expected as that work continues. For Spinosaurus mirabilis, the next step is deeper comparison with other spinosaurid fossils from across North Africa and continued analysis of how its skull, sail and limbs functioned together. The discovery’s first formal description is now published, but many details about the animal’s full body and behavior will depend on what future digs and ongoing lab work can confirm.
Author note: Last updated 2026-02-22.