Centrosaurus apertus

Overview

Centrosaurus apertus was a large horned dinosaur of Late Cretaceous North America. Its nasal horn and frill behind the head make a strong impression. Fossils ranging from juveniles to adults reveal how much the face changed during growth.^[1]

Key facts

Horn ornaments do not always become larger with age. A 2014 study presented evidence that some ornaments actually became smaller in mature Centrosaurus. Dinosaur growth can include unexpected twists.^[1]

Time and place

The Cretaceous spans approximately 143–66 million years ago, and this species lived in North America during its later part. It left abundant fossils in the Belly River Group, and the Dinosaur Park Formation in present-day Alberta, Canada, is important for growth studies. Comparing individuals within the same formation narrows differences in time when examining growth.^[1][2][3]

The time range describes source context, not the complete duration of this species.

Size, form and skeleton

A nasal horn and hook-like projections along the frill margin characterize its face. In the growth sequence proposed by a 2014 study, the nasal horn changes from backward-curving to straight and then forward-curving. Frill projections also change in length and direction of curvature during growth.^[1]

The Natural History Museum in London gives a body length of about 6 m for the genus Centrosaurus.^[7]

Habitat and reproduction

Bonebeds containing many fossils of one dinosaur species preserve evidence of juveniles through adults. Such fossils enrich questions about Centrosaurus growth. Comparing body size, head ornamentation, and bone surfaces reveals different growth stages.^[1]

Fossil discovery

In 2014, researchers compared 47 skull specimens to analyze their growth sequence. Rather than simply arranging larger skulls as older individuals, they examined bone fusion, surface texture, and horn orientation together. Multiple specimens combined to tell the story of a species growing up.^[1]

References

1. Frederickson & Tumarkin-Deratzian (2014), Craniofacial ontogeny in Centrosaurus apertus
2. International Commission on Stratigraphy (2024) — Geological time chart
3. PALAIOS — Study of a Centrosaurus bonebed in the Dinosaur Park Formation of Alberta, Canada
4. PLOS ONE — The head and growth of Stegoceras
5. Frederickson & Tumarkin-Deratzian (2014), Craniofacial ontogeny in Centrosaurus apertus
6. PALAIOS — Study of a Centrosaurus bonebed in the Dinosaur Park Formation of Alberta, Canada
7. Natural History Museum, London — Centrosaurus

Research questions

Changes in horn orientation during growth have also been studied in Triceratops. Comparing the nasal horn of Centrosaurus with the brow horns of Triceratops reveals a shared question about growth in different faces. It is important to read several clues together rather than rely on one feature.^[1]

Observation

After examining the nasal horn’s orientation, follow the edge of the frill. Compare whether projections extend backward or curve inward or downward. Growth is recorded not only in skull size but also in ornament shape and bone surfaces.^[1]