Spicomellus afer was discovered back in 2019 and later described in 2021 based on a strange-looking rib bone palaeontologist Professor Susannah Maidment acquired from a fossil dealer in Cambridge.
While the fossil was known to come from Boulemane, Morocco, exactly where it was found was unknown. This prompted Maidment and a team of British, American and Moroccan palaeontologists to visit the area in an attempt to find more Spicomellus remains.
They found a lot more bones than they ever imagined they would, revealing Spicomellus was not only incredibly strange, but also covered in spikes - from its neck to the very tip of its tail.
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Spicomellus belongs to a family of armoured dinosaurs known as ankylosaurs. These herbivorous dinosaurs looked a lot like today’s armadillos, but they were roughly the size of rhinos.
As well as looking incredibly strange, Spicomellus is the oldest ankylosaur currently known to science, at 165 million years old. This makes it incredibly important from an evolutionary perspective as it highlights just how much ankylosaurs changed over the course of their roughly 100-million-year-long existence.
“When we originally named Spicomellus, there were doubts that it was an ankylosaur at all. Now, not only can we confirm beyond a doubt that this interpretation was correct, but Africa’s only known ankylosaur is far weirder than anyone imagined,” explained Maidment in a recent article published by the Natural History Museum.
“Spicomellus had a diversity of plates and spikes extending from all over its body, including metre-long neck spikes, huge upwards-projecting spikes over the hips, and a whole range of long, blade-like spikes, pieces of armour made up of two long spikes, and plates down the shoulder. We’ve never seen anything like this in any animal before.
“To find such elaborate armour in an early ankylosaur changes our understanding of how these dinosaurs evolved. It shows just how significant Africa’s dinosaurs are, and how important it is to improve our understanding of them.”
Ever since it was discovered in 2019, scientists have known Spicomellus wasn’t like other dinosaurs. The rib it was described from had spikes growing directly out of the bone - a feature not seen in other dinosaurs. While spines, spikes, and plates are well known amongst dinosaurs and other reptiles, they’re typically embedded in skin, not fused to bones.
The recent expedition in Morocco uncovered even more spiky bones, including a bone collar that had an 87cm-long spike projecting from it. This bone collar would have sat around Spicomellus’ neck and protected it from predators.
The end of Spicomellus’ tail hasn’t been found, but based on the fact that its tail vertebrae bear a lot of similarities to those of ankylosaurs with tail clubs, it’s presumed it also wielded a weapon of some variety. This is unusual as it was long thought the earliest ankylosaurs didn’t have tail weapons.
The fact that Spicomellus likely had one, as well as armour plates that protected its hips, changes what we thought we knew about ankylosaur evolution.
“The combination of a tail weapon and a sacral shield, armour plates which protect the hips, suggest that many of the ankylosaurs’ key adaptations already existed by the time of Spicomellus,” said Maidment.
While Spicomellus’ armour no doubt provided it with some form of protection against predators, it’s thought its spikes were used more for display - whether that be for attracting mates, warding off rivals, or a combination of both.
As ankylosaurs evolved, their armour became less and less extravagant, but arguably more functional. Maidment and her team think this adoption of more functional and protective armour was in response to the appearance of larger predators. They also suggest this trend may have been driven by a change in how ankylosaurs attracted mates and settled disputes, moving on from visual displays to full-scale combat.
Maidment and her team’s recent findings were published in the science journal Nature and can be found here.
Find out more about the study: Extreme armour in the world’s oldest ankylosaur, published in the journal Nature.
Top image: Matthew Dempsey, from Nature study
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