Skin-derived osteoderms in Jurassic deposits confirm that ankylosaur armor existed early in the group. New Spicomellus remains show that earlier ankylosaurs had far more elaborate armor, with backs bristling with sharp spines and outer-edge spikes. Each rib may have borne up to six spikes, and several spikes reached nearly a meter, resembling lances. The largest armaments were on the neck, where fused osteoderms formed massive half-collars that extended five or more long spikes; three such cervical structures occurred. Tail vertebrae bear handles indicating a weaponized tail. These features represent extreme dermal armour modifications outside known ankylosaur morphologies, complicating precise family placement.
The small, solid-looking spikes found along the edges of later ankylosaurs? Forget those. Spicomellus had a back that was probably bristling with sharper spines, along with far larger ones along its outer edges. Each rib appears to have generated as many as six individual spikes. At a handful of locations, these spikes extended out to nearly a meter, looking more like lances than anything needed to ward off a close-in attack.
And the largest of these were along its neck. On the upper surface of its neck, several osteoderms fused to form a massive half-collar of bone and then extended out five or more individual spikes, each among the longest on the animal's body. And there were three of these structures along the neck. "No known ankylosaur possesses any condition close to the extremely long pairs of spines on the cervical half-ring of Spicomellus," its discoverers note.
As if its hedgehog-on-acid appearance weren't enough, handles present on the tail vertebrae suggest that it also had a weaponized tail. All told, the researchers sum things up by saying, "The new specimen reveals extreme dermal armour modifications unlike those of any other vertebrate, extinct or extant, which fall far outside of the range of morphologies shown by other armoured dinosaurs."
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