Spicomellus afer African ankylosaur with spiky armor and tail club

A partial skeleton unearthed in Morocco has revealed an unusually spiky early ankylosaur that rewrites ideas about how the group evolved. The specimen, identified as Spicomellus afer and dated to roughly 165 million years ago in the Middle Jurassic, bears an array of bony spikes fused to ribs, a broad bony collar around the neck with meter-long spikes, and indications of a club-like tail. Researchers say the combination and elaboration of these armored features are unique among vertebrates and suggest that complex displays and tail weapons appeared far earlier in ankylosaur history than previously thought.

The new material expands on a 2021 find of a single rib fragment and provides multiple elements including vertebrae, ribs, pelvic fragments and associated osteoderms. Several ribs preserve spikes that are integral to the bone, not simple skin plates, and one nearly complete cervical spike measures about 87 centimeters in length. Tail vertebrae appear to be partially fused into a handle-like structure that could have supported a tail club, a feature formerly believed to have evolved tens of millions of years later.

Lead investigators described the specimen as unlike any other...