A novel spinosaur species boasting a spectacular head crest is detailed, and its discovery location provides compelling evidence in the closely watched dinosaur debate: were these giants creatures of the sea or semi-aquatic? To secure such a valuable find, paleontologists had to search within a war-torn region of the world’s largest desert, and they found ways to express gratitude to the local populace. This fresh research was published in the journal Science.
For a long time, spinosaurs didn’t enjoy the same public recognition as North American dinosaur species, gaining only modest attention through one of the less memorable Jurassic Park films. Nevertheless, they have commanded significant scientific interest during the contention over whether they were nearly fully aquatic animals, occupying a niche already held by mosasaurs and ichthyosaurs, or if they more closely resembled extant crocodiles or even massive marsh birds.
Until recently, all spinosaur fossils had been unearthed on the Gondwanan edges of the Tethys Sea of that epoch, which offered no help in resolving this matter. Perhaps they inhabited river deltas and estuaries, or perished after venturing near the coast while foraging. The recovery of spinosaur remains in northern Niger, a location at least 500 kilometers from the nearest Tethys shoreline at the time of their demise, shifts the dynamics of this discussion.
Along with bones clearly belonging to a spinosaur species and those attributable to other types, a research contingent spearheaded by University of Chicago Professor Paul Sereno uncovered a large, curved bone they could not immediately identify. Eventually, they determined it was a massive crest, likely utilized for sexual signaling, situated on the skull of a spinosaur.
Since none of the previously discovered fossil spinosaurs possessed a crest, this had to represent a new species, which the team dubbed Spinosaurus mirabilis in honor of this magnificent adornment.
The texture and interior composition of the bone suggest to Sereno and his co-authors that it was sheathed in keratin—a material known from hair, nails, and rhinoceros horns. It was likely vibrantly colored and employed exclusively by males to attract females and warn off rivals.
“The find was so sudden and astonishing; it was truly an emotional moment for our team,” Sereno stated. “I will forever recall that moment in camp when we gathered around a laptop to see the new species for the first time, after one of our members generated 3D digital models of the recovered bones to assemble the skull—powered by solar energy in the middle of the Sahara. That’s when the magnitude of the discovery truly registered with me.”
Any possibility that the discovery indicated an arm of the Tethys extending inland was negated by the presence of sauropod fossils recovered from the same strata. Instead, S. mirabilis dwelled in a wooded environment dissected by rivers and likely spent time both in water and on land. While this doesn’t prove other spinosaur species lived in analogous ecosystems, the differences among known spinosaur fossils, excluding the crest, are too slight to warrant assuming radically divergent lifestyles.
Further excavation at the site yielded additional spinosaur specimens, enabling the authors to confirm that the lower jaw teeth projected outward between the upper teeth, much like in modern crocodiles.
For Sereno, this solidifies long-held suspicions about the spinosaur’s diet, as such dental arrangement functioned as a trap for slippery fish and has evolved in other predominantly piscivorous species, including ichthyosaurs and pterosaurs. Of course, we are aware that crocodiles do not allow their tooth placement to impede them from consuming larger prey, and the spinosaur likely did not either. As these examples illustrate, the teeth do not settle the aquatic versus semi-aquatic lifestyle dispute, so fortunately, the habitat likely does.
“I envision this dinosaur as a kind of ‘hellish heron,’ wading without issue on its robust legs into water up to two meters deep, but probably spending most of its time stalking large fish in shallower territories,” Sereno remarked.
The story behind these discoveries is as striking as the story of the species themselves. Back in the 1950s, a geologist from what was then French North Africa found gigantic, saber-shaped teeth. He deemed it so insignificant that he devoted only a single sentence to it in a monograph, yet Sereno noted its similarity to the Carcharodontosaurus teeth found in Egypt.
“No one had returned to that precise location where the teeth were found for over 70 years,” Sereno explained. He reasoned: why let such a difficult-to-reach place, whose name translates to “No Water, No Goat,” and an Islamist insurgency prevent further investigation into such a find?
“It was a genuine adventure—traversing the sandy expanse to find that site, and then locating an even more remote area bearing the fossils of a new species,” he recalled. Fortunately for the team, they encountered a local Tuareg man who had spotted enormous bones deep within the desert, and he provided them with a full day’s transport on his motorcycle to the discovery spot. The team found spinosaur teeth and jawbones almost immediately upon arrival.
Niger, even prior to the recent surge in conflicts, was one of the world’s poorest nations with one of the lowest life expectancies. Rather than viewing this as a reason to avoid Niger, Sereno is determined to showcase its fossil wealth to the local people and the wider world. He is leading an international effort to establish the world’s first zero-energy museum in the capital, Niamey. The River Museum is set to be constructed on an island in the middle of the river that gave the country its name. In addition to Niger’s Cretaceous heritage, the museum will pay tribute to the people who inhabited the region when the Sahara was a verdant savanna.
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