The armored tank of the dinosaur world was a slow, low-slung herbivore

Nature · Published 3 October 2026 Swipe more like this →

In short: Ankylosaurs were the living fortresses of the Jurassic and Cretaceous periods. Encased in a mosaic of bony plates and often armed with a massive tail club, these quadrupedal herbivores moved slowly across the landscape. Despite their formidable appearance, they possessed surprisingly weak jaws and teeth, suggesting a diet of soft plants.

Ankylosaurs, or armored dinosaurs, are defined by their extensive covering of osteoderms—bony plates, studs, and horns that shielded their backs and flanks. These creatures were generally low and broad, walking on short, stout legs in a quadrupedal stance. Their skeletal structure, including columnar limbs and broad, hooflike terminal phalanges, indicates a slow, graviportal mode of locomotion. Unlike many other ornithischians, ankylosaurs had limited jaw muscle attachment and small, leaf-shaped teeth, implying they were specialized for consuming soft, pulpy vegetation.

The group is traditionally divided into two main families: the basal Nodosauridae and the more advanced Ankylosauridae. The most distinct feature separating these groups is the tail club; advanced ankylosaurids possessed a massive bony weapon at the end of their tails, a feature entirely absent in nodosaurs. Additionally, ankylosaurids typically exhibited broader, more heavily bone-encrusted skulls. In some species, such as Euoplocephalus, this armor even extended to the eyelids, which developed protective bony coverings.

While ankylosaurs are primarily associated with North America, Europe, and Asia, their evolutionary history remains a subject of ongoing study. They belong to the broader group Thyreophora, which also includes the stegosaurs. While historically linked to stegosaurs due to shared characteristics like osteoderms, ankylosaurs followed a distinct evolutionary path characterized by the development of skull-surface armor and a consolidated carapace. The exact timing of their divergence from stegosaurs remains unknown, and the fossil record for their earliest origins is sparse, with only a few specimens known from the Middle Jurassic.

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