Body length
InferredApproximately 6 m reference length.
ROM reconstruction estimate; the fossil's missing limbs and reconstructed body do not establish a population range. [D3]
EXHIBIT 257
Zuul
Zuul crurivastator
Dinosaur
A horned, armored ankylosaur from Montana with a tail club and unusually preserved skin. [3]
TWO WAYS TO PICTURE THE PAST
Science & the silver screen
Compare the evidence with the familiar movie image. The illustrations are not to a shared scale.
01 / SOURCE-INFORMED RECONSTRUCTION
A life reconstruction from the evidence
Image unavailableIllustrative life reconstruction of Zuul in a period-appropriate environment; coloration and missing anatomy are interpretations.The exhibit and its credited image source remain available.
An illustrative reconstruction. Compare its anatomy with the evidence and limitations in the dossier. [1]
Source-informed reconstruction. Appearance evidence [1]. Original illustration; missing anatomy, coloration and scenery include interpretation.
Fossils constrain this life reconstruction. Missing anatomy, coloration and the environmental scene include interpretation; the dossier explains the evidence limits.
02 / MOVIE-STYLE INTERPRETATION
A cinematic imagination
Image unavailableIllustrative reconstruction of Zuul crurivastator; missing anatomy, pose, skin and colors are hypotheses.The exhibit and its credited image source remain available.
An illustrative reconstruction. Compare its anatomy with the evidence and limitations in the dossier. Lighting, coloration and scenery are artistic choices. This image does not document a fossil locality or behavior.
Original artwork · artistic interpretation.
Scientific view: source-informed reconstruction, credited paleoart or specimen-based imagery. Movie-style view: Original artistic interpretation. Reconstructions involve uncertainty.
PERIODLate Cretaceous[1]
DIETHerbivoreEvidence and uncertainty in the dossier
TOTAL LENGTH6–6 mEstimate scope matters
FOSSILS FOUNDUnited States[1]
MEET THE ANIMAL
Meet Zuul
Zuul was an armored plant-eating dinosaur from Montana. Its short rounded snout, horns behind the eyes and large tail club help distinguish it from other ankylosaurs. The museum's reconstruction is about six meters long. This gives a useful idea of scale, while remaining an estimate based on fossil evidence and restored missing parts. [D3]
The famous specimen preserves much more than an ordinary set of bones. Skin and armor remained associated with the body, letting researchers study how the protective covering was arranged. Its legs are missing, however, so even this exceptional fossil is incomplete. Preserved tissue also does not automatically reveal the animal's original color, its sex or every detail of its appearance. [D4]
Some armor spikes along its sides were damaged and healed while the animal was alive. Researchers think the location of these injuries fits strikes from another ankylosaur's tail club. This supports a possible combat explanation, but it does not preserve the fight itself. It also cannot tell us how often Zuul gathered in groups or exactly how an individual chose a mate. [D2]
PREHISTORIC ANIMAL DOSSIER
A life in profile.
The animal, the evidence, and the questions still open.
Armor injuries provide unusually specific evidence for possible combat between ankylosaurs, while leaving the animal's sex and daily social life unresolved. [D2]
Profile scope: The exhibit concerns Zuul crurivastator, named from the exceptional holotype ROM 75860. [D1]
- Time
- Late Cretaceous
- Fossil locations in this exhibit
- United States
How to read the evidence
Source supported identifies a description documented by the cited source. Inferred marks a reconstruction or functional estimate. Debated marks competing interpretations. Not established means the sources reviewed for this dossier do not support a firm conclusion; it does not mean a behavior never occurred.
A size reference is an estimate, not a population range. Nesting evidence does not by itself establish courtship, mate choice, or lifelong pairing.
Body mass
InferredApproximately 2,500 kg reference mass.
Museum estimate, rather than a measured fossil-individual mass or an adult species interval. [D3]
Diet and feeding
InferredPlant eating inferred.
The museum identifies this ankylosaur as herbivorous; preferred plants and a specimen-specific meal remain unresolved. [D3]
Habitat and setting
InferredMontana alluvial coastal plain.
Coal Ridge Member channel deposits lie within a terrestrial floodplain system; burial near a seaway does not imply marine life. [D1]
Movement
InferredFour-legged ground movement.
The ankylosaur body plan supports quadrupedal restoration; original limb geometry remains partly comparative because legs are missing. [D4]
Recognizable anatomy
InferredShort rounded snout, rear skull horns and clubbed tail.
Preserved skin and armor retain arrangement; fossil tissue does not establish the animal's living color. [D1]
Reproduction & life together
Reproduction and nesting
Not establishedNot established here
No Zuul egg or nest established. The exceptional body fossil does not assign reproductive remains or preserve parenting behavior. [D1]
Mating and courtship
Not establishedNot established here
Sexual-selection explanations remain hypotheses. Healed flank injuries may indicate ritualized contests, but cannot establish sex, breeding season or mating displays. [D4]
Social behavior
InferredPossible combat between individuals.
Flank injuries fit tail-club strikes; healing-rate differences or infection remain alternatives. The specimen does not establish herds. [D2]
Dossier research & sources
Sources and inspection notes for the claims in this profile.
- Arbour and Evans (2017), A new ankylosaurine dinosaur from the Judith River Formation of Montana, USARoyal Society Open Science · Accessed 2026-10-08Full original description inspected, including skull, tail, preserved tissues and Coal Ridge Member setting. · Inspected: page
- Arbour, Zanno and Evans (2022), Palaeopathological evidence for intraspecific combat in ankylosaurid dinosaursBiology Letters · Accessed 2026-10-08Full study inspected; localized healed armor damage supports a combat hypothesis rather than direct observation. · Inspected: page
- Royal Ontario Museum identifies spectacular new species of armoured dinosaur (2017)Royal Ontario Museum · Accessed 2026-10-08Institutional announcement inspected for educational size estimates and anatomy. · Inspected: page
- How One Amazing Fossil Is Upending Our Understanding of Ankylosaur Behavior (2024)Natural History Museum of Utah · Accessed 2026-10-08Complete indexed interview inspected; missing legs, unknown sex and tissue preservation discussed without adopting sensational certainty. · Inspected: excerpt
THE STORY IN THE FOSSILS
Evidence behind Zuul
The unusually preserved tail combines a stiffened handle, terminal club and rows of pointed armor. Together with the skull, these features supported recognition of a distinct animal. [1]
Healed damage differs from burial damage. Its flank concentration led researchers to consider strikes from another ankylosaur. [2]
A note on scale and time
The dossier identifies the scope of each reference estimate. A mount, an individual fossil and a species-wide adult range are different measurements. Comparison metrics remain unavailable where adult scope has not been established. Unknown does not mean zero.
Sources & editorial notes
Sources support the stated claims and scopes. Refer to the evidence notes for uncertainty.
- Arbour and Evans (2017), A new ankylosaurine dinosaur from the Judith River Formation of Montana, USARoyal Society Open Science · Accessed 2026-10-08Full original description inspected, including skull, tail, preserved tissues and Coal Ridge Member setting. · Inspected: page
- Arbour, Zanno and Evans (2022), Palaeopathological evidence for intraspecific combat in ankylosaurid dinosaursBiology Letters · Accessed 2026-10-08Full study inspected; localized healed armor damage supports a combat hypothesis rather than direct observation. · Inspected: page
- Royal Ontario Museum identifies spectacular new species of armoured dinosaur (2017)Royal Ontario Museum · Accessed 2026-10-08Institutional announcement inspected for educational size estimates and anatomy. · Inspected: page
- How One Amazing Fossil Is Upending Our Understanding of Ankylosaur Behavior (2024)Natural History Museum of Utah · Accessed 2026-10-08Complete indexed interview inspected; missing legs, unknown sex and tissue preservation discussed without adopting sensational certainty. · Inspected: excerpt
KEEP EXPLORING
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