New Spinosaurus Species Found 1,000 Kilometers From the Nearest Shore - With a Scimitar Crest

The discovery began with a single sentence buried in a French geological monograph from the 1950s: a geologist had mentioned finding a sabre-shaped fossilized tooth in the central Sahara, resembling those of the giant predator Carcharodontosaurus. No one had returned to that site in over 70 years.

Paul Sereno, a professor of Organismal Biology and Anatomy at the University of Chicago, went back. In November 2019, led deep into the Sahara by a local Tuareg man on a motorbike, his team found teeth and jaw bones from what would turn out to be an entirely new species of Spinosaurus. A return expedition in 2022 recovered two additional crests, confirming what they had found. The discovery is reported in Science, with Sereno as senior author of a 30-person multinational team.

The new species is named Spinosaurus mirabilis - "remarkable Spinosaurus" - and it possesses a bony crest so large and unexpected that the team initially did not recognize it when they first picked the fragments up from the desert surface.

The Scimitar Crest

The crest of S. mirabilis curves skyward in a blade-like arc, quite different from the taller, straighter sail of the better-known Spinosaurus aegyptiacus. Based on the surface texture and interior vascular canals of the crest, the researchers believe it was sheathed in keratin and likely brightly colored in life. They interpret it as a visual display structure - useful for species recognition or competition - rather than a functional adaptation for swimming or thermoregulation.

"This find was so sudden and amazing, it was really emotional for our team," Sereno said. "I'll forever cherish the moment in camp when we crowded around a laptop to look at the new species for the first time, after one member of our team generated 3D digital models of the bones we found to assemble the skull - on solar power in the middle of the Sahara."

Another anatomical feature distinguishes S. mirabilis: interdigitating tooth rows, where lower teeth protrude between upper teeth, creating a trap well-suited for catching slippery fish. This dental arrangement appears independently in several fish-eating lineages - aquatic ichthyosaurs, semi-aquatic crocodilians, flying pterosaurs - and in spinosaurids it is considered a defining trait.

Far From the Shore

Until this discovery, spinosaurid bones and teeth had been found primarily in coastal deposits, close to the shoreline of the ancient Tethys Sea. That geographic pattern had led some researchers to propose that spinosaurids were fully aquatic - pursuing prey underwater like giant crocodilians. The hypothesis had been controversial.

S. mirabilis complicates that picture significantly. The Niger site, named Sirig Taghat - meaning "no water, no goat" in Tamasheq, the local Berber language - lies as much as 1,000 kilometers from the nearest marine shoreline that existed when the dinosaur was alive, between 100 and 95 million years ago. The animal was buried alongside the remains of long-necked sauropod dinosaurs, in river sediments consistent with a forested inland habitat cut through by rivers.

Sereno describes S. mirabilis as a "hell heron" - a predator comfortable wading into two meters of water on sturdy legs while also stalking shallow fish traps along riverbanks. The comparison suggests a more flexible ecological role than fully aquatic pursuit would allow.

A Third Phase of Spinosaurid Evolution

The discovery supports a model in which spinosaurids went through three evolutionary phases. The first began in the Jurassic Period when the lineage developed its elongated skull for fish-catching. The second, in the Early Cretaceous, saw spinosaurids spread as predators along the Tethys Sea coast. The third phase - represented by S. mirabilis and relatives in South America - produced specialists adapted for shallow-water predation in inland river systems of northern Africa and South America, as the Tethys coastline began to retreat.

The find adds to Niger's already substantial contribution to paleontology. Sereno has worked in the country for 30 years, excavating more than 100 tons of fossil material. He is also leading an effort to build the Museum of the River in Niamey, a zero-energy institution designed to showcase Niger's paleontological and archaeological heritage.