Scientists working in the remote Sahara Desert of Niger have uncovered fossils of a previously unknown species of Spinosaurus, one of the largest meat-eating dinosaurs ever to walk the Earth, according to research published Thursday.
The newly identified species, named Spinosaurus mirabilis, lived around 95 million years ago during the Cretaceous Period and stood out for a towering, scimitar-shaped bony crest rising from its skull. Researchers say the dinosaur measured roughly 40 feet (12 metres) in length and weighed between five and seven tonnes, making it comparable in size to the largest known predatory dinosaurs.
Unlike land-based hunters such as Tyrannosaurus rex, Spinosaurus mirabilis was adapted for a semi-aquatic lifestyle. Its elongated, crocodile-like snout and interlocking conical teeth were designed to trap slippery prey, while the placement of its nostrils allowed it to keep breathing as most of its head remained submerged. Scientists believe it waded into rivers and shallow waterways to hunt large fish, much like a modern heron.
The fossil remains, including parts of three skulls and other bones, were found far inland, hundreds of kilometres from any ancient coastline. This discovery challenges long-standing theories that Spinosaurus was a fully aquatic, open-ocean predator, instead supporting the view that it was a shallow-water hunter inhabiting river systems within a forested interior landscape.
Researchers say the dinosaur’s prominent cranial crest was likely used for display rather than combat, possibly playing a role in attracting mates or asserting dominance over feeding territories. The crest, thought to have been covered in keratin, may have been brightly coloured in life.
Spinosaurus mirabilis is only the second confirmed species within the Spinosaurus genus, which first entered the scientific record in 1915 with the discovery of Spinosaurus aegyptiacus in Egypt. While both species shared the distinctive sail-like structure on their backs and fish-eating adaptations, the newly discovered species had a larger head crest, a more elongated snout and longer hind limbs.
The fossils were uncovered during a challenging expedition launched from the city of Agadez in 2022, with researchers travelling for days across difficult desert terrain. Alongside the Spinosaurus remains, the team also found fossils of other ancient animals preserved in sandstone outcrops.
Palaeontologists say the discovery reshapes understanding of Spinosaurus ecology and cements its status as one of the most unusual and specialised predators of the dinosaur era, marking a major step forward in reconstructing Africa’s prehistoric past.