Spicomellus

Chapter • Meet the dinosaur

Overview

Spicomellus afer was a stocky, four-legged plant-eater roughly three to four metres long, built low and wide with heavy limbs and a barrel-shaped body. What made it famous is its armour. A pair of enormously long, backward-sweeping spikes rose from the neck – the longest preserved example measures about 87 centimetres – and the neck itself carried fused bony collars bristling with points. Over the hips sat a shield of fused bony plates bearing blade-like, sword-shaped projections, while the rear tail vertebrae were fused into a stiff handle. No tail club is known, but that stiffened tail end shows such structures began evolving far earlier in ankylosaur history than anyone expected. Like all ankylosaurs, Spicomellus had no feathers: its body was covered in skin studded with bony osteoderms. As an armoured dinosaur it moved slowly and close to the ground, probably rarely exceeding a brisk walk. The spikes are interpreted in the scientific literature as serving both defence and display: structures as extreme, long and partly fragile as the neck spikes work poorly as pure protection but superbly as visual signals towards rivals and members of the same species. Whether these animals lived alone or in groups is unknown, since no bonebed with multiple individuals has been found. The teeth were small and leaf-shaped, set in short jaws beneath a broad, low head – standard equipment for cropping soft, low-growing vegetation such as ferns, cycads and conifer shoots. Ankylosaurs did not chew like mammals; they snipped off plant material and let a capacious gut do the work, which explains the wide, barrel-like torso. Spicomellus was named in 2021 by Susannah Maidment and colleagues on the basis of a single Moroccan rib in which the spikes grew directly out of the bone – a condition never before seen in any vertebrate, living or extinct. In 2025 far more material from the same locality was published, revealing the neck collar, the pelvic shield and the stiffened tail, and turning Spicomellus into one of the most bizarre dinosaurs ever found. The fossils come from the El Mers III Formation at Boulahfa near Boulemane in the Middle Atlas Mountains, and at roughly 165 million years old Spicomellus is the oldest securely known ankylosaur in the world.

Chapter • Where it lived

Habitat

Spicomellus lived in the Middle Jurassic, in the Bathonian stage roughly 168–165 million years ago. Every known fossil comes from the El Mers III Formation at Boulahfa, south of Boulemane in the Middle Atlas Mountains of Morocco. At that time the region lay along the margin of the shallow Tethys Sea, and the sediments record low-lying coastal plains with river channels, temporary lakes and periodically flooded mudflats. The vegetation consisted of ferns, cycads, ginkgos and conifers; flowering plants had not yet appeared in any quantity. The same beds have produced the stegosaur Adratiklit boulahfa along with sauropod and theropod remains, making the site one of the most important windows onto Middle Jurassic dinosaur life in Africa.

Chapter • Wild behavior

Behavior & Ecology

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Chapter • Scientific place

Taxonomy