In the rugged badlands of Morocco’s Middle Atlas Mountains, a dinosaur bristling with spikes once lumbered across the Jurassic floodplains. It was not the squat, club-tailed Ankylosaurus of textbooks, but something far stranger.
A new partial skeleton of Spicomellus afer has confirmed what palaeontologists long suspected: the world’s oldest ankylosaur looked like no other animal, living or extinct.
A Dinosaur Dressed to Impress
“Our study reveals a new specimen of the ankylosaur Spicomellus afer, which is the oldest known ankylosaur in the fossil record and the first from Africa,” lead author Susannah Maidment of London’s Natural History Museum told ZME Science.
The initial description of the species was published in 2021 and was based on one rib bone. The newly excavated remains near the Moroccan town of Boulemane reveal one of the most elaborate armor structures seen among dinosaurs: meter-long spikes projecting from a bony neck collar, smaller spikes erupting from its ribs, a shield of spikes across its hips, and evidence of a tail weapon whose exact form remains a mystery.
Based on the preserved elements, palaeontologists think Spicomellus was a medium-sized ankylosaur, probably in the range of 4 to 5 meters long (13–16 feet). That’s much smaller than Cretaceous giants like Ankylosaurus (6–8 m), but still hefty, about the size of a car.
This armour was as much for show as it was for protection against attacks. The neck spikes alone, nearly a meter in length, would have been cumbersome to carry. “They’re also very visually striking, especially from the front. So we think they could have been used for some sort of display: either to scare off predators, or in courtship displays perhaps,” Maidment explains.
In other words, Spicomellus may have been part warrior, part show-off.
Why So Spiky?
Ankylosaurs are best known from the Cretaceous, when they swung massive tail clubs against predators like T. rex. But Spicomellus lived around 165 million years ago, in the Middle Jurassic, making it roughly 30 million years older than any ankylosaur previously known.
The new fossil includes two special “handle” vertebrae in the tail. These bones are a smoking gun: in later ankylosaurs they formed the stiffened base needed to wield a heavy club. Their presence in Spicomellus suggests that tail weapons evolved far earlier than scientists thought. “This suggests that tail weapons might have been a feature possessed by many ankylosaurs, and these were lost through their evolution in some forms and elaborated into clubs in others,” says Maidment.
This pushes back the timeline of dinosaur weaponry and hints that the arsenal of ankylosaurs was more diverse than once imagined.
If later ankylosaurs pared down their armour, why did their ancestors start so extravagantly? Scientists think sexual selection might hold the key. In living animals, flamboyant structures — stag antlers, peacock tails — often evolve as mating displays. The costly, oversized spikes of Spicomellus could have served the same role.
“No other vertebrate possesses the exceptionally elaborate dermal armour of Spicomellus,” the study authors write. Early ankylosaurs may have flaunted their spikes to impress mates or intimidate rivals, only later co-opting simpler armour for pure defence when predators grew larger and more dangerous.
Maidment notes that the shift may also reflect changing social behaviour. “Perhaps, through their evolution, social structures and behaviour changed so that such display structures were no longer required.”
Rethinking Armored Dinosaurs
This more detailed description of Spicomellus is important for ankylosaur evolution. Instead of starting modestly and bulking up over time, ankylosaurs may have begun with armour at its most flamboyant before simplifying into the more practical forms seen in the Cretaceous. It’s a clear example that evolution is never about becoming ‘stronger’ or ‘more complex’ but rather simply selects the most fit individuals in a population for a given environment.
For Maidment, that makes Spicomellus extremely interesting: “This incredibly elaborate armour might have been used for display as well as defence, and it changes our understanding of the development of ankylosaur armour, suggesting it actually got simpler and less elaborate through the evolution of the group.”
The dinosaur’s very name — Spicomellus, “collar of spikes” — now feels almost understated.
The fossil was found in 2023 in the El Mers III Formation, a Middle Jurassic deposit near Boulemane. Excavating in Morocco posed challenges, Maidment recalls. “When we started our collaborative work together, there were no vertebrate palaeontologists working in Moroccan universities, no natural history museums in which we could place the fossils we were finding, and no labs to clean and prepare the fossils for study.”
The project has since helped change that. Her team established a lab and fossil collection at Sidi Mohamed Ben Abdellah University in Fes, and has been training Moroccan researchers in excavation and preparation. The Spicomellus skeleton is now housed there.
The findings appeared in the journal Nature.
