EXPLORE PREHISTORY 220 prehistoric animal profiles · Scientific & movie-style image galleries
DinoGrove.
The collection/Chasmosaurus

EXHIBIT 74

Chasmosaurus

Chasmosaurus

Chasmosaurus was a horned plant eater from Late Cretaceous Canada. A rare juvenile skeleton reveals that its frill changed in shape as well as relative size during growth. [1] [3]

Evidence profile

TWO WAYS TO PICTURE THE PAST

Compare the evidence with the familiar movie image. The illustrations are not to a shared scale.

01 / FOSSIL VIEW

The evidence in the bones

Mounted Chasmosaurus fossil cast at the North American Museum of Ancient Life, showing its large open frill.

Chasmosaurus fossil-cast skeleton at the North American Museum of Ancient Life. The photograph is identified at genus level; posture and missing skeletal parts are reconstructed. The mount does not establish living color or soft tissues. [3]

Chasmosaurus skeleton · Ninjatacoshell. CC BY-SA 3.0. Commons-listed 1280 px preview converted to WebP; smaller responsive copy resized. No crop or color changes; these copies remain CC BY-SA 3.0.

The photograph or figure shows the credited fossil material; displayed mounts and labels can include interpretation.

02 / MOVIE-STYLE INTERPRETATION

A cinematic imagination

Illustrative reconstruction of Chasmosaurus with a long neck frill, nasal horn and four supporting legs.

Original cinematic interpretation of Chasmosaurus. Anatomy, soft tissues and colors are reconstructed choices. 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 LENGTHSee the dossierEstimate scope matters
FOSSILS FOUNDCanada, Alberta[1]
CompareRead the dossierView the sources

MEET THE ANIMAL

Meet Chasmosaurus

Chasmosaurus was a plant-eating horned dinosaur from Late Cretaceous Canada. Its beak gathered vegetation and a large neck frill shaped its head. It walked on four legs, but a museum size reference cannot describe every individual or growth stage. [D1]

A rare young skeleton from Alberta's Dinosaur Park Formation was described at about 1.5 metres long. Its bones were articulated, meaning they remained together in their connected order. This individual preserves an informative growth stage rather than a standard adult body or a complete account of parental care. [D2]

The youngster's frill was proportionately shorter than an adult's and narrowed toward the back. Adults had a different outline, so growing up involved changing shape instead of merely enlarging a miniature adult. Comparing such individuals helps separate developmental differences from other explanations for variation between skulls. [D3]

Names must also follow particular specimens. A 2026 study placed the former Chasmosaurus russelli type in Cryptarcus, a separate genus. That change does not automatically reassign every historical Chasmosaurus fossil. Keeping the juvenile's published identity separate preserves what its growth evidence actually shows. [D5]

PREHISTORIC ANIMAL DOSSIER

A life in profile.

The animal, the evidence, and the questions still open.

A Chasmosaurus juvenile shows how its elongated frill changed during growth. [D3]

Profile scope: Chasmosaurus at genus level. The former C. russelli type CMNFV8800 was assigned to Cryptarcus in 2026 and is excluded. Juvenile evidence retains the genus assignment reported in 2016; no new species referral is asserted. [D2] [D5]

Time
Late Cretaceous
Fossil locations in this exhibit
Canada, Alberta
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.

Length

Inferred

About 5 m (museum reference)

NHM gives a rounded genus reference without a specimen, method or maturity. Separately, the described juvenile skeleton was 1.5 m; that is a growth-stage observation. [D1] [D2]

Mass

Inferred

About 2,500 kg (museum reference)

This rounded genus estimate lacks specimen, method and maturity; it is neither the juvenile's weight nor a population average. [D1]

Diet and feeding

Inferred

Plant eater with a cropping beak

NHM identifies herbivory and a beak; preferred plants remain unresolved. [D1]

Habitat and setting

Source supported

Late Cretaceous Alberta

The juvenile was collected from the Dinosaur Park Formation in Dinosaur Provincial Park. Its locality establishes provenance rather than a demonstrated preferred habitat. [D2]

Movement

Inferred

Four-legged walking

NHM describes quadrupedal movement; speed and gait details remain unresolved. [D1]

Distinctive anatomy

Source supported

A frill that changed during growth

The juvenile frill was proportionately shorter and narrowed toward its rear. Adults had a different posterior shape, showing more than simple enlargement. [D3]

Reproduction & life together

Reproduction and care

Not established

Not established here

A juvenile skeleton supplies growth evidence, but does not establish nest structure, incubation or parental care.

Courtship and mating

Inferred

Frill display proposed

One paper proposed sexual selection for frill ornament, but its version 1 has peer review marked not approved. This remains an unconfirmed proposal and establishes no mating ritual. [D4]

Social behavior

Not established

Not established here

The reviewed specimens and profiles do not establish Chasmosaurus herd structure or cooperative care.

Dossier research & sources

Sources and inspection notes for the claims in this profile.

  1. Chasmosaurus — Dino DirectoryNatural History Museum, London · Accessed 2026-10-02Genus-level educational profile; 5 m and 2,500 kg references omit specimen, method and maturity. · Inspected: page
  2. A juvenile chasmosaurine ceratopsid from the Dinosaur Park Formation, Alberta, CanadaJournal of Vertebrate Paleontology; Currie and colleagues (2016) · Accessed 2026-10-02Indexed abstract inspected: articulated 1.5 m juvenile Chasmosaurus skeleton and juvenile frill anatomy; full paper not inspected. · Inspected: abstract
  3. Charting the growth of one of the world's oldest babiesUniversity of Alberta; research-team account (2016) · Accessed 2026-10-02Researcher discussion of juvenile/adult proportions and frill shape; findings from one juvenile rather than proven parental care. · Inspected: page
  4. Systematics of Chasmosaurus - new information from the Peabody Museum skull, and the use of phylogenetic analysis for dinosaur alpha taxonomyF1000Research; Nicholas Longrich (2015), version 1; peer review: 1 not approved · Accessed 2026-10-02Indexed discussion excerpt inspected. This version has one peer review marked not approved; its sexual-selection proposal is retained only as an unconfirmed hypothesis, not an accepted mating account. · Inspected: excerpt
  5. New information on the holotype of Chasmosaurus russelli (Ornithischia: Ceratopsidae) necessitates the establishment of a new genus to receive the speciesCanadian Journal of Earth Sciences; Holmes, Mallon, Ryan and Evans (2026) · Accessed 2026-10-02Original paper retained locally; abstract and discussion inspected for the reassignment of the former C. russelli type CMNFV8800 to Cryptarcus. This update does not reassign other historical Chasmosaurus specimens. · Inspected: excerpt

THE STORY IN THE FOSSILS

Meet Chasmosaurus.

Chasmosaurus was a plant-eating horned dinosaur with a long neck frill. NHM places its Canadian fossils in the Late Cretaceous, approximately 76–74 million years ago. Rounded museum size references provide an introduction, rather than a complete range for every species and life stage. [1]

An articulated juvenile skeleton from Alberta, described in 2016, measures 1.5 m long. Its frill differed from the adult outline, offering a rare view of growth. Finding a young animal preserves a life stage, but does not on its own reveal how its parents behaved. [2] [3]

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.

  1. Chasmosaurus — Dino DirectoryNatural History Museum, London · Accessed 2026-10-02Genus-level educational profile; 5 m and 2,500 kg references omit specimen, method and maturity. · Inspected: page
  2. A juvenile chasmosaurine ceratopsid from the Dinosaur Park Formation, Alberta, CanadaJournal of Vertebrate Paleontology; Currie and colleagues (2016) · Accessed 2026-10-02Indexed abstract inspected: articulated 1.5 m juvenile Chasmosaurus skeleton and juvenile frill anatomy; full paper not inspected. · Inspected: abstract
  3. Charting the growth of one of the world's oldest babiesUniversity of Alberta; research-team account (2016) · Accessed 2026-10-02Researcher discussion of juvenile/adult proportions and frill shape; findings from one juvenile rather than proven parental care. · Inspected: page
  4. Systematics of Chasmosaurus - new information from the Peabody Museum skull, and the use of phylogenetic analysis for dinosaur alpha taxonomyF1000Research; Nicholas Longrich (2015), version 1; peer review: 1 not approved · Accessed 2026-10-02Indexed discussion excerpt inspected. This version has one peer review marked not approved; its sexual-selection proposal is retained only as an unconfirmed hypothesis, not an accepted mating account. · Inspected: excerpt
  5. New information on the holotype of Chasmosaurus russelli (Ornithischia: Ceratopsidae) necessitates the establishment of a new genus to receive the speciesCanadian Journal of Earth Sciences; Holmes, Mallon, Ryan and Evans (2026) · Accessed 2026-10-02Original paper retained locally; abstract and discussion inspected for the reassignment of the former C. russelli type CMNFV8800 to Cryptarcus. This update does not reassign other historical Chasmosaurus specimens. · Inspected: excerpt

FOLLOW YOUR CURIOSITY

Who will you meet next?

KEEP EXPLORING

More from the collection

Illustrative reconstruction of Pentaceratops with a long frill, brow and nasal horns and projecting cheek horns.
Movie-style interpretation
Late Cretaceous

Pentaceratops

Pentaceratops sternbergii

Pentaceratops was a horned plant eater from Late Cretaceous New Mexico. Its name counts the prominent cheek projections alongside the nasal and brow horns, while disputed giant material requires separate treatment.

HerbivoreMeet this animal
Three-horned Triceratops on four legs in a forest, with a large textured frill and rugged skin.
Movie-style interpretation
Late Cretaceous

Triceratops

Triceratops horridus

Triceratops horridus was a horned dinosaur of the Late Cretaceous. Skin impressions attributed to this species reveal scales, while skulls and their positions in rock layers help researchers distinguish it from the later Triceratops prorsus.

HerbivoreMeet this animal