For the first time since the early 20th century, indisputable evidence of a new species of Spinosaurus has been found.
This latest discovery, made by a 20-person team led by the University of Chicago’s Paul Sereno, includes jaw fragments, several teeth and three scimitar-shaped head crests.
The first of these crests was unearthed in 2019; three years later, in 2022, a larger team returned to the site and found two more, revealing they belonged to a previously unknown species.
It’s thought, based on the crests’ surface texture, they were sheathed in keratin and brightly coloured, serving as display structures that would have attracted others of the same species. They may have also grown to a height of 50 cm, making them the tallest cranial crest of any non-avian dinosaur.
“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. That’s when the significance of the discovery really registered.”
Named for its astonishing head crest, Spinosaurus mirabilis was found at a newly discovered site known as Jenguebi. This fossiliferous area lies in Niger’s central Sahara and, based on its geology, it reflects an environment that was forested, dissected by rivers, and hundreds of kilometres away from shore.
Since Spinosaurus was first described by German palaeontologist Ernst Stromer in 1915, there has been a lot of debate surrounding its way of life. This debate has largely been fuelled by the fact the original fossils Spinosaurus was described from were destroyed in a British bombing campaign in Munich during World War II, shrouding it in mystery.
Previously, fossils belonging to Spinosaurus and its closest kin - known as spinosaurids - had only really been found in coastal deposits not far from shore. This, on top of the long list of aquatic adaptations inferred from their skeletons, led some researchers to suggest they may have been semi to fully aquatic, pursuing large prey, such as coelacanths (a group of ancient fish), underwater.
However, S.mirabilis may have just put a pin in this particular theory, based on the fact it lived inland and, according to Sereno and his team, some 500-1000 km from the nearest coastline.
Instead, Sereno "envisions this dinosaur as a kind of 'hell heron’ that had no problem wading on its sturdy legs into two metres of water but probably spent most of its time stalking shallower traps for the many large fish of the day.”
Another striking feature of S.mirabilis’ skull is its jaws. The tooth rows are arranged in an interdigitating manner, meaning teeth on the lower jaw protrude outward and between those on the upper jaw. This is an adaptation seen in a lot of fish-eating predators, including ichthyosaurs, crocodiles and pterosaurs, and it suggests S.mirabilis was adept at catching slippery fish.
Sereno and his team have been digging in the Sahara for decades. While it may be barren today, this area was once home to an incredible diversity of dinosaurs during the Cenomanian age of the Late Cretaceous, 95 million years ago.
“If you can brave the elements and are willing to go after the unknown, you might just uncover a lost world,” said Sereno of digging in the desert.
On top of this latest study, Sereno plans to show off replicas of S.mirabilis’ skull and its scimitar-shaped head crest at the Chicago Children’s Museum on 1 March.
“Letting kids feel the excitement of new discoveries - that’s key to ensuring the next generation of scientists who will discover many more things about our precious planet worth preserving,” he concluded.
The study, titled 'New scimitar-crested Spinosaurus species from the Sahara caps stepwise spinosaurid radiation', was published today in Science - find out more here.
Top image: Palaeontologist Paul Sereno marvels at the skull cast of the first dinosaur to be named from the Jenguebi fossil area, the spinosaurid Spinosaurus mirabilis. Credit: Keith Ladzinski
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