Dinosaurs / Cretaceous / Polacanthus
Polacanthus
Cretaceous pol-uh-KAN-thus, “many thorns”
Polacanthus was an Early Cretaceous ankylosaurian discovered on the Isle of Wight in England by the Reverend William Fox. Reaching around four to five metres in length, it was an extensively armoured herbivore adapted for low-level feeding. Its distinguishing characteristic was a massive, fused sheet of dermal bone, known as a pelvic buckler, which sat securely over its lower back and hips. Flanking its neck and torso were several rows of prominent, triangular bony spines and hollow keeled scutes. Like other polacanthines, it did not possess a heavy tail club, relying instead on its bristling spines and fused body armor to dissuade predators. Polacanthus shared its subtropical riverine habitat with numerous well-known dinosaurs, including Neovenator, Hypsilophodon, and Iguanodon.
It featured a solid, fused bony shield known as a pelvic buckler covering its hips and rump.
Where and when
Polacanthus lived in the Early Cretaceous, from 130 to 125 million years ago (Barremian age). Its remains come from United Kingdom, in the Wessex Formation.
The numbers
Length 4.5 m (estimates run from 4 to 5 m). Mass about 1.2 t. Hip height about 1.1 m. That is 2.6 human-lengths, or 0.4 of a double-decker bus. These are estimates from partial skeleton; fields marked estimated by the site are length, mass, hip height.