New Dome-Headed Pachycephalosaur from Montana and Spicomellus from Morocco Reveal Bizarre Armor Evolution Across North America and Africa

Paleontologists have announced two extraordinary finds that illuminate the weirdest armoured dinosaurs: a new pachycephalosaur with an unusually ornate dome from Montana’s Hell Creek Formation and additional spectacular material of the “Godzilla hedgehog” ankylosaur Spicomellus afer from Morocco.

The Montana specimen, described in 2026 in Cretaceous Research, belongs to a new species of Sphaerotholus and preserves a dome covered in dozens of small, radially arranged bony knobs and a prominent midline ridge — features never seen before in North American pachycephalosaurs. At ~68 million years old, the animal was a small, bipedal herbivore whose thickened skull likely served in head-ʙuттing or display.

Meanwhile, new Spicomellus fossils from the Middle Jurᴀssic of Morocco, published in Nature (August 2025), confirm metre-long spikes fused directly to its ribs — the most extreme armour ever recorded in any vertebrate. The 4-metre-long ankylosaur also possessed a tail weapon 30 million years earlier than previously known.

Together these discoveries show that elaborate cranial domes and extravagant body armour evolved independently in different lineages and continents during the Jurᴀssic and Cretaceous. The Montana pachycephalosaur is housed at the Museum of the Rockies, while Spicomellus material resides in Moroccan and UK collections.

These finds prove that the “tank” dinosaurs of North America and Africa were far stranger and more spectacular than anyone imagined.