From the dusty ridge tops of Morocco, paleontologists have found a really cool ankylosaur. Spicomellus afer lived in the Middle Jurassic, about 165 million years ago, making it the oldest known ankylosaur. A heavily spiked skeleton is its standout feature, including a bizarre, meter-long spiked collar fused directly to its ribs.
Detective Work led to the fossils
This dinosaur’s story began in 2019 when a fossil dealer in Cambridge offered a dinosaur rib to Dr. Susannah Maidment at the London Natural History Museum. When she and her team studied it, they found that spines were embedded into the rib itself, fused bone to bone. This was a remarkable discovery.
© The Trustees of the Natural History Museum, London
Her team wanted to learn more. This X Thread from the London Natural History Museum describes in detail the detective work that Dr. Maidment undertook to find more fossils of this ankylosaur.
They knew that the original rib had come from Morocoo, but where exactly, they didn’t know. Dr. Maidment’s team used geology and interviews to zero in on a more exact location. Eventually, in 2023, a team of British, American and Moroccan palaeontologists were able to mount an expedition to the region to search for more of Spicomellus’s remains.
Fortunately for us, and obviously for them too, they found much more of the skeleton than they initially hoped for. The find revealed that the dinosaur’s entire body was covered in spikes.
By 2025, researchers were able to publish a paper describing a much more complete specimen. It confirmed that this amazing dinosaur had rib spikes, but also a (relatively) long neck, hip, sideblade armour, and even a tail weapon. That tail structure alone predates all known ankylosaur tail clubs by over 30 million years.
Dr. Maidment called it “bizarre”
The spikes on the dinosaur were long, almost impractical. The longest spikes were almost a metre long (87cm), and were likely made longer by the presence of keratin sheaths. In fact, at this size, the armour raised serious questions about its use. Especially because the spikes were fused to the ribs, and this would have caused issues in regular movement.
“This collar of spikes would have been one of several around Spicomellus’ neck,” said Dr. Maidment. “While other ankylosaurs have cervical collars made out of a ring of bony plates, there’s nothing quite like this.”
“It’s particularly strange, because this is the oldest known ankylosaur. We might expect that some later species might have inherited similar features, but they haven’t.”
Its tail wasn’t completely found, but the preserved vertebrae show a fusion forming a “handle”. This was enough information to identify a hallmark of tail clubs found only in later Cretaceous ankylosaurs. “The presence of ‘handle’ vertebrae in the tail of Spicomellus indicates that it possessed a tail weapon, overturning current understanding of tail club evolution in ankylosaurs” the team wrote in their paper. “These structures were previously thought to have evolved only in the Early Cretaceous”
Spicomellus also featured a sacral shield (armour over the hips) and small spikes embedded in armour plating. That is compact and comprehensive defense.
The blade-like bones are believed to have lined the dinosaur’s sides. © The Trustees of the Natural History Museum, London
No consensus yet on what the armour was for
Researchers speculate that the armour first evolved first for defence. Over time it may have pivoted its purpose for attracting mates and showing off to rivals.
Dr. Maidment explains, “It would have been very energetically expensive to produce and carry around such extraordinary armour”. Additionally, it would have made movement difficult.
Such massive spikes do eventually get left behind in ankylosaur evolution. Later ankylosaurs have mostly functional armour, mainly for defence.
Perhaps, this came down to the simultaneous evolution of larger predators. This could forced ankylosaurs to simplify their armour and more defensive. Elaborate displays would cost an amount of energy that they simply would not have any more.
Smaller spikes were embedded in Spicomellus’s armour plating. © The Trustees of the Natural History Museum, London
Ankylosaur Evolution Reimagined
Before Spicomellus, ankylosaurs were known from the Cretaceous and mostly from the Northern half of Pangea, Laurasia. Suddenly, scientists have found one from the Middle Jurassic of Gondwana, pushing back tail-weapon evolution by millions of years.
“Morocco has a strong background in classical geology, but discoveries like this show the importance of palaeontology as well,” said Prof. Ouarhache, Université Sidi Mohamed Ben Abdellah. “We’ve never seen dinosaurs like this before, and there’s still a lot more this region has to offer.”In fact, Spicomellus is the only ankylosaur we know of from Africa.These findings show that tail clubs and elaborate armour were already part of ankylosaur evolution long before scientists expected.