Scientists Discover First New Spinosaurus Species in a Century — a 'Hell Heron' from the Inland Sahara
A team led by the University of Chicago has named Spinosaurus mirabilis, a scimitar-crested, fish-eating theropod found 500–1,000 km from the nearest ancient sea, reshaping what scientists know about where spinosaurs lived.
Overview
Paleontologists have named a new species of spinosaurid dinosaur — Spinosaurus mirabilis — discovered in the remote inland deserts of Niger. The find, published in Science this week, is the first new spinosaurid species formally described in more than a century. The discovery is also challenging a long-held assumption that these large, fish-eating theropods were confined to coastal environments: S. mirabilis lived roughly 500 to 1,000 kilometers from the nearest ancient sea.
The Discovery
An international team led by Paul Sereno, a professor of organismal biology and anatomy at the University of Chicago, first unearthed a distinctive fossilized crest fragment in Niger’s central Sahara in 2019. The feature was so unusual that researchers initially did not recognize it as part of a spinosaur skull, according to the University of Chicago. The team returned to the same site in 2022 and recovered additional specimens, assembling enough material to formally describe a new species.
The fossils came from inland river deposits dated to approximately 95 million years ago during the Cretaceous period. The specimens were CT-scanned and digitally reconstructed at Sereno’s Fossil Lab in Chicago, with replicas now slated to debut at the Chicago Children’s Museum.
What Makes It Unusual
Spinosaurs are known from Africa, Europe, and South America, and have historically been associated with coastal or near-coastal environments — riversides and deltas near ancient seas where they could pursue large fish. S. mirabilis breaks that pattern, according to phys.org. The fossils were recovered alongside long-necked sauropod skeletons in what was once a forested, river-dissected interior landscape, not a coastal margin.
The species’ most striking feature is its enormous scimitar-shaped head crest — a blade arching skyward from the skull. Based on the crest’s surface texture and internal vascular channels, researchers believe it was sheathed in keratin and brightly colored in life, functioning as a visual display structure for species recognition. The skull also bears interlocking teeth in which the lower jaw teeth protrude outward between those of the upper jaw, forming what researchers describe as a trap for catching slippery fish.
At roughly school-bus length and several tonnes in weight, S. mirabilis is large even by spinosaurid standards.
The ‘Hell Heron’ Model
Sereno describes S. mirabilis as a kind of “hell heron” — a wading predator that could venture into roughly two meters of water but likely spent most of its time hunting in shallower riverbank environments, as reported by NPR. The comparison to modern herons reflects the animal’s probable hunting strategy: stalking shallow water on sturdy legs rather than swimming or diving.
The characterization runs counter to influential interpretations, proposed over the past decade, that Spinosaurus aegyptiacus — the type species of the group — was a dedicated aquatic predator akin to a giant crocodilian. ScienceDaily notes that the paper argues S. mirabilis “caps stepwise spinosaurid radiation,” representing one of the last-surviving members of a lineage that diversified over roughly 50 million years. The inland habitat and wading behavior suggest that spinosaurid ecology was more varied than the aquatic-specialist model implies.
Scientific Significance
The last formally described spinosaurid species was named in the early twentieth century, making S. mirabilis a rare addition to a group that has been the subject of sustained scientific debate. The spinosaur body plan — elongated skull, conical teeth, and adaptations for fish predation — is well-established, but questions about exactly how aquatic these animals were, and where they lived, have remained contested.
The University of Chicago describes the find as contributing to understanding the final chapter of spinosaurid evolution. The inland fossil locality expands the known geographic range of the group and adds new data to ongoing arguments about whether spinosaurs were obligate water-dwellers or a more ecologically flexible lineage capable of exploiting inland river systems far from the coast.
What Remains Unknown
The scientific debate over spinosaur aquatic behavior is not settled by a single specimen. The extent to which S. mirabilis represents a distinct ecological strategy versus regional variation within a broadly similar lineage remains an open question. Researchers will need to assess whether the inland location reflects a population that permanently occupied interior river systems or whether the fossil represents an animal that had wandered from a broader coastal range.
The function of the scimitar crest — whether purely for display, thermoregulation, or some combination — also remains uncertain, as preserved soft tissue evidence is absent. Future expeditions to the Niger site may recover additional specimens that clarify the species’ anatomy and ecology.