Zuul

Chapter • Meet the dinosaur

Overview

Zuul crurivastator was a heavily armoured, barrel-bodied plant-eater that walked on four short, pillar-like legs. It measured roughly six metres from snout to tail tip and carried rows of bony plates, called osteoderms, embedded in the skin of its back and neck. Blade-like spikes projected from its flanks, and the broad skull bore short horns sweeping back over the neck plus a pair of pyramid-shaped horns beneath the eyes. The whole head was sheathed in a mosaic of fused bony tiles, and the tail ended in a massive club supported by a stiffened handle of interlocking vertebrae. Like other ankylosaurids, Zuul was a slow, low-slung animal that could not outrun a predator. Its defence lay in armour and in that tail club, which could be swung sideways with considerable force. The species name crurivastator, "destroyer of shins", refers to the idea that such a blow could shatter the leg bones of an attacking tyrannosaur such as Gorgosaurus. A 2022 study of the holotype found that several spikes along the animal's flanks had been broken and had healed, while the tail club itself was undamaged. The researchers interpret this as evidence that Zuul individuals fought one another side-on, rather than that the injuries came from predators. Zuul fed on low-growing vegetation. Its broad, shovel-shaped muzzle and small, leaf-shaped teeth were suited to cropping ferns, horsetails, cycads and early flowering plants close to the ground. Ankylosaurids had a hugely capacious body cavity housing a long gut, where tough plant material could ferment and be broken down by microbes, because the teeth were not built for efficient grinding. The fossil was found in 2014 in the Judith River Formation near Havre, Montana, USA, by a crew that was actually excavating a Gorgosaurus. The skeleton – holotype ROM 75860, now at the Royal Ontario Museum in Toronto – includes a complete skull, the entire tail with its club, and much of the body with osteoderms and skin impressions preserved in life position. That makes Zuul one of the best-preserved ankylosaurs ever described. Victoria Arbour and David Evans named the species in 2017, borrowing the genus name from the monster Zuul in the 1984 film Ghostbusters because the skull reminded them of the creature's face.

Chapter • Where it lived

Habitat

Zuul lived about 76 million years ago, during the Campanian age of the Late Cretaceous, on the humid coastal lowlands west of the Western Interior Seaway that then split North America in two. All known fossils come from the Judith River Formation of Montana, USA – a landscape of meandering rivers, floodplains, lagoons and forests of cycads, ferns, conifers and early flowering plants. Hadrosaurs, ceratopsians and predators such as Gorgosaurus shared the same environment.

Chapter • Wild behavior

Behavior & Ecology

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Chapter • Scientific place

Taxonomy