In 2019, paleontologist Paul Sereno and a 20-person team were prospecting ancient river deposits in the central Sahara when they spotted bone fragments weathering out of rust-colored sandstone. The site sat hundreds of kilometers from the nearest paved road and roughly 1,000 kilometers from any modern coastline. What emerged over the following years of excavation, CT scanning, and digital reconstruction was a predatory dinosaur no one had seen before: a spinosaur with a curved, blade-like crest rising from its skull like the sweep of a scimitar.
In June 2026, the team’s formal description of the animal was published in Science. They named it Spinosaurus mirabilis, the species epithet drawn from the Latin for “wonderful,” a reflection of the crest that sets it apart from every known relative.
A skull from deep inside a continent
The partial skull was recovered from the Farak Formation in Niger, a geological unit built from inland river and riverbank sediments laid down between 100 and 95 million years ago, during the mid-Cretaceous. According to the University of Chicago expedition summary, the team used solar-powered equipment to build 3D digital models of the fossil on-site before transporting it for laboratory analysis, a logistical achievement given the extreme remoteness of the dig.
The inland setting is the detail that carries the most scientific weight. Paleogeographic reconstructions in the paper place the Farak Formation as far as 1,000 kilometers from the margin of the ancient Tethys Sea. Previous spinosaur discoveries, including the Spinosaurus aegyptiacus tail material described in a 2022 Nature study, came from coastal or near-shore environments. S. mirabilis is the first spinosaur recovered from deposits that are unambiguously deep-continental, meaning the animal hunted fish in freshwater rivers far from any ocean.
The scimitar crest and a new evolutionary framework
The crest itself is a laterally compressed, curved blade of bone visible in CT scans and digital reconstructions hosted by Sereno’s lab. Nothing quite like it has been documented in other spinosaurids, which tend toward elongated snouts and, in some species, tall dorsal sails.
In the University of Chicago press release, Sereno described the moment the crest’s shape became clear during CT scanning: “When we saw that curved blade of bone resolve on screen, we knew this was a spinosaur unlike any in the record.” He added that the animal’s deep-inland provenance was equally striking: “Finding a spinosaur 1,000 kilometers from the nearest ancient shoreline tells us these predators were far more versatile than anyone assumed.”
Drawing on the new skull and comparisons with other spinosaurid fossils, the research team proposes that spinosaur evolution unfolded in three broad phases: an initial radiation along coastlines, a transitional period in estuarine and deltaic habitats, and a final push into fully inland river systems. The model is laid out in Figure 4 and the accompanying supplementary materials (sections S7 through S9) of the Science paper. S. mirabilis, with its novel cranial anatomy and deep-continental provenance, represents that third phase. The AAAS summary of the research frames this as evidence that spinosaurs were far more geographically versatile than the coastal-predator image that has dominated popular reconstructions for decades.
Open questions
The crest’s function remains unresolved. Display for species recognition or mate selection is one possibility, analogous to the crests of hadrosaurs and pterosaurs. A hydrodynamic role during rapid movement through shallow water has also been floated, but no fluid dynamics simulations or finite element analyses have been published to test the idea. Until quantitative biomechanical work is done, any claim about what the crest did during the animal’s life stays speculative.
Size is another gap. The paper is based on a partial skull, and no public estimate of total body length has appeared in press materials. Readers familiar with S. aegyptiacus, often cited as one of the largest known theropods at roughly 14 meters, will want to know how S. mirabilis compares. That answer likely depends on finding more postcranial material in future field seasons.
The three-phase evolutionary model, while well-argued, is an interpretation built on a still-sparse fossil record. If future spinosaur discoveries cluster closer to ancient shorelines, paleontologists may favor a more coastal-centered narrative with only occasional inland forays. Conversely, additional deep-continental finds would strengthen the case that river-dwelling spinosaurs were common, not exceptional.
The broader ecology of the Farak Formation also awaits fuller documentation. Press materials mention large river systems and abundant fish, but detailed faunal lists and paleoenvironmental reconstructions have not been widely circulated. Without knowing what other predators, herbivores, and aquatic reptiles shared the habitat, placing S. mirabilis precisely within its food web is premature.
Published commentary on the find has so far come almost entirely from Sereno’s team. Independent assessments from other spinosaur specialists will sharpen the picture, particularly around the evolutionary model and the taxonomic placement of the new species within the genus Spinosaurus versus a potentially distinct genus.
What the geology settles and what it does not
For readers trying to weigh the discovery, the clearest takeaway is geological. The Farak Formation’s inland fluvial character is a physical fact about rock layers, not an inference about behavior. Sedimentary deposits record where they formed, and if the formation genuinely sat 1,000 kilometers from the Tethys margin, then the animal preserved within it lived far from any ocean. That single data point reshapes the spinosaur story more than the crest does, because it establishes habitat range through hard stratigraphy rather than anatomical guesswork.
The species name, its geological provenance, and the 100-to-95-million-year age bracket are peer-reviewed facts tied to physical specimens. These are unlikely to change barring dramatic new evidence. The riparian habitat interpretation and the stepwise evolutionary model are well-supported analytical conclusions, but they remain open to revision as new fossils surface. And any specific behavioral claims, whether about hunting style, swimming ability, or crest function, are working hypotheses that await independent testing.
What is no longer debatable is that spinosaurs ranged far deeper into continental interiors than the field assumed even a few years ago. Spinosaurus mirabilis, scimitar crest and all, is the fossil that forces that update. The next chapters will be written in the same rust-colored sandstone of the central Sahara, whenever the next expedition can get there.
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*This article was researched with the help of AI, with human editors creating the final content.
