Armoured dinosaur’s ‘crazy’ spikes weren’t just for defence

A dinosaur fossil found in Morocco may be the most bizarrely and elaborately armoured vertebrate that has ever walked the planet.

The first fossil of Spicomellus afer was discovered in Morocco and reported in 2021. It was only a rib fragment with fused spikes, suggesting that it belonged to a group of dinosaurs known as ankylosaurs. These short-limbed, wide-bodied herbivorous dinosaurs are characterised by their covering of plates and spines.

Then, in October 2022, a farmer in the badlands of Morocco’s Middle Atlas mountains began to excavate a much more complete Spicomellus skeleton. That fossil has now been dated to 165 million years ago, in the Jurassic Period. The creature was probably about 4 metres long and weighed up to 2 tonnes.

Armoured dinosaurs such as stegosaurs and ankylosaurs, like modern crocodiles, had bony plates that sat in the skin called osteoderms. But in the Spicomellus fossil, there are two different types of bony armour: osteoderms and spikes that are actually fused to the bone.

“It’s unheard of among armoured dinosaurs, and indeed anything that has osteoderms, which is totally crazy,” says Susannah Maidment at the Natural History Museum in London, a member of the team that analysed the fossil.

In total, the Spicomellus specimen has dozens of armoured spikes covering almost its entire body. Some spikes attached to a neck collar are nearly a metre in length. There are also fused vertebrae in the tail, indicating that it may have been a fierce weapon.

The creature was so bizarre, says Maidment, that she “ran out of hyperboles to describe it”. “You can’t use words like ‘crazy’ in a scientific paper, and I kept using words like extreme and elaborate,” she says. “Then one of my colleagues suggested another way of trying to get across the unusualness of this thing was to describe it in the study as ‘baroque’.”

Such extreme armour would have severely limited the species’ capacity to navigate its environment and would have made living anywhere with dense vegetation almost impossible, says Maidment. “It would have just kept getting stuck everywhere,” she says.

The armour is so complex that the researchers think it had another function in addition to defence, such as to attract mates. “Things that appear to be totally impractical in the fossil record almost invariably relates to sex in some way or other. And so, you know, we think it is most likely to be some sort of display.”

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