New Scimitar-Crested Spinosaurus mirabilis Discovered in Niger's Sahara

A groundbreaking discovery in the central Sahara Desert of Niger has unveiled a new species of large carnivorous dinosaur, Spinosaurus mirabilis. This significant find, spearheaded by a University of Chicago team, includes unique skull fragments, jawbones, and distinctive scimitar-shaped head crests.

The discovery not only enriches our understanding of spinosaurid evolution but also offers fresh evidence in the ongoing scientific debate regarding the aquatic adaptations and habitat of Spinosaurus species, suggesting S. mirabilis primarily inhabited inland river systems as a wading predator.

Discovery Details

The expedition, led by Paul Sereno, Professor of Organismal Biology and Anatomy at the University of Chicago, unearthed the fossils at the Jenguebi site in Niger. The search was sparked by a 1950s monograph by a French geologist, which referenced a sabre-shaped fossilized tooth in a remote location. Initial findings of crest and jaw fragments occurred in November 2019, with additional crests and skull components discovered in 2022.

An international team of 20, aided by a local Tuareg guide, excavated over 100 tons of fossil finds. Among these, 55 tons were specimens directly related to Spinosaurus mirabilis. The new species is estimated to have lived approximately 95 million years ago during the Late Cretaceous period. These pivotal findings were published in Science in February 2026, with Paul C. Sereno and other young scholars credited as co-authors on the paper titled "New scimitar-crested Spinosaurus species from the Sahara caps stepwise spinosaurid radiation."

Anatomy and Characteristics of Spinosaurus mirabilis

Spinosaurus mirabilis, meaning 'astonishing Spinosaurus' or 'wonderful spine lizard,' is estimated to have been around 40 feet (12 meters) long and weighed 5-7 tons, comparable in size to a Tyrannosaurus Rex. Its distinct features include:

• Head Crest: A prominent scimitar-shaped, blade-like, or horn-like crest on its skull. This crest is estimated to have reached up to 0.5 meters (20 inches) tall, making it the tallest known cranial crest of any non-avian dinosaur. Analysis of the crest's surface texture and vascular canals suggests it was covered in keratin. Researchers hypothesize this crest served as a brightly colored display feature for communication, potentially in sexual or territorial competition.
• Dentition: Interdigitating upper and lower tooth rows, where lower jaw teeth protrude between upper jaw teeth. These cone-shaped teeth resemble those of modern crocodiles and ancient fish-eating reptiles, indicating an adaptation for catching slippery prey. The skull also featured retracted nostrils.
• Other Features: The species also possessed a large, sail-like structure on its back and an elongated, crocodile-like snout.

When compared to Spinosaurus aegyptiacus, identified in 1915 from Egyptian fossils, S. mirabilis distinguishes itself with a larger crest, a more elongated snout, more spaced-out teeth, and longer hind limbs.

Habitat and Aquatic Lifestyle Debate

The discovery site for Spinosaurus mirabilis is located deep inland in Niger's central Sahara, approximately 300-1000 kilometers from the nearest ancient marine shoreline. Geological analysis indicates that this area was a forested environment traversed by rivers during the Late Cretaceous period, with the fossils found buried in river sediments. Associated fossil finds include partial skeletons of long-necked dinosaurs, Carcharodontosaurus, crocodiles, turtles, and large freshwater fish species.

The inland location and skeletal features of S. mirabilis contribute significantly to an ongoing scientific debate regarding the aquatic adaptations of Spinosaurus species:

Wading Predator Hypothesis

Paul Sereno's research team proposes that Spinosaurus mirabilis was primarily a wading predator, hunting large fish in shallow waters up to 2 meters (6 feet) deep. Sereno has characterized the dinosaur as a "hell heron" or a "giant, heron-like animal." The team's analysis comparing the skull, neck, and back leg traits of Spinosaurus species to various living and extinct predators suggests they functionally align more closely with wading birds like herons and storks than with fully aquatic animals. This interpretation suggests the species was a poor swimmer that did not dive for its meals, with the weight of its back sail potentially hindering deep-water swimming.

Sereno's team presents this discovery as a significant challenge to the hypothesis that Spinosaurus was fully aquatic and an open-water marine predator.

Alternative/Previous Hypotheses (More Aquatic)

Some previous research, particularly following the 2014 discovery of Spinosaurus aegyptiacus fossils in Morocco, suggested that Spinosaurus spent a significant portion of its life in water, potentially as a strong swimmer. Paleontologist Nizar Ibrahim, who led the 2014 study, cited features such as heavy bones optimized for buoyancy and a tail structured for underwater propulsion.

Ibrahim has expressed skepticism regarding the "wading only" interpretation for Spinosaurus, noting that its estimated weight and dense bone tissue contrast with the typically long legs and light bodies of wading birds. He argues that the dinosaur's size would necessitate opportunistic hunting strategies, potentially including ambushing land animals crossing waterways.

Combined Strategies

Other paleontologists, such as Matt Lamanna, suggest that Spinosaurus might have employed multiple hunting strategies, including both wading and swimming, with ambush being a common method, rather than being analogous to fully aquatic animals like dolphins.

The debate is expected to continue as scientists await more complete Spinosaurus skeletons for further analysis.

Expedition and Paleontological Legacy

The expedition faced difficult desert conditions, necessitating the use of solar power for generating 3D digital models of bones for skull assembly. At the South Side Fossil Lab in Chicago, Sereno's team meticulously cleaned and CT scanned the fossils to create precise digital renderings. Paleoartists then used these models to produce detailed flesh reconstructions, including a 3D physical model and an animated depiction for the Science cover, showcasing advancements in paleontological visualization techniques.

The discovery contributes significantly to Niger's paleontological and archaeological record. Paul Sereno has also directed the development of the Museum of the River in Niamey, Niger's capital. This museum is intended to exhibit regional paleontological finds, including the new Spinosaurus species, and evidence of Stone Age cultures in the Green Sahara. Replicas of the skull and a touchable model of the scimitar crest will be displayed at the Chicago Children's Museum as part of Sereno's Dinosaur Expedition exhibit, aiming to engage children with these groundbreaking new discoveries.