A spectacular new fossil discovery in Morocco has unveiled the world’s oldest known ankylosaur, Spicomellus afer, a heavily armoured dinosaur bristling with extraordinary spikes. The find, published in Nature, challenges long-held assumptions about how and why these iconic plant-eating dinosaurs evolved their distinctive armour.
Ankylosaurs are best known from the Late Cretaceous of North America and Asia,where tank-like species such as Ankylosaurus carried bony plates and wielded tail clubs for protection. Their earlier history, however, has remained elusive due to a poor fossil record. In 2021, Spicomellus was tentatively identified from a single rib with fused spikes, but doubts lingered over whether it was truly an ankylosaur. The new specimen, unearthed in Morocco’s Middle Atlas Mountains, dispels those uncertainties.
The skeleton reveals a dazzling array of defensive and decorative features: ribs with spikes fused to their tops, a pelvic shield studded with plates and most strikingly, a collar of neck armour bearing spikes nearly a metre long. The tail bones also include “handle vertebrae,” indicating the presence of a tail weapon,once thought to have evolved tens of millions of years later. No living or extinct animal exhibits such extravagant armour diversity.
Fig. 1: A life reconstruction of an ankylosaur showing hypothetical positions of armour
The discovery pushes the origins of ankylosaur tail weapons back by about 30 million years and suggests that their elaborate armour may not have been purely defensive. Instead, the energy-intensive neck collar and ornate spikes likely evolved under sexual selection, serving as display features or as weapons in intraspecific combat, much like deer antlers. Later ankylosaurs, living alongside larger predators in the Cretaceous, may have simplified this armour into flatter plates better suited for defence.
Fig. 2: A simplified time-calibrated strict reduced consensus tree showing the putative phylogenetic position of S. afer.
Beyond evolutionary insights,the find underscores the importance of Moroccan fossil sites. The research team, a UK-Morocco collaboration,has established fossil preparation labs and training programs in Fez to combat illegal fossil trade and build local palaeontological expertise.
The extraordinary armour of Spicomellus afer forces a major rethink of ankylosaur origins. Rather than a slow march toward heavier protection,these dinosaurs may have begun with flamboyant,baroque displays only later streamlining their armour into the tank-like forms that once roamed the Cretaceous.
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Reference：
Maidment,S.C.R.,Ouarhache,D.,Ech-charay,K. et al. Extreme armour in the world’s oldest ankylosaur. Nature (2025). https://doi.org/10.1038/s41586-025-09453-6
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