Centrosaurus apertus

Centrosaurus apertus was one of the most abundant large herbivores in the Dinosaur Park Formation of Alberta. It carried a single prominent nasal horn above the beak, small brow horns and a short frill ornamented with hook-like processes. Dozens of dense bonebeds contain remains from juveniles through adults, making Centrosaurus exceptionally important for reconstructing ceratopsid growth, population structure and mass-death events. Those deposits show that large numbers gathered at least occasionally, but they do not prove that every individual lived permanently in one enormous herd.

Its fossils occur between approximately 76.5 and 75.5 million years ago. Values shown here are approximate and reflect the current curated seed dataset.

The skull was deep and narrow with a parrot-like beak, shearing dental batteries and a long nasal horn that varied in curvature between individuals and through growth. The relatively short frill had two large openings and a pair of inward-curving hooks near its rear margin, with smaller scallops around the edge. A massive neck, barrel-shaped torso and four sturdy limbs supported the head. Juveniles began with small, differently oriented ornaments; the nasal horn and frill hooks changed shape as the skull matured.

• Large nasal horn with variable forward or backward curvature
• Short frill pierced by two large parietal openings
• Pair of inward-hooking ornaments at the rear of the frill
• Reduced brow horns above the eyes
• Powerful beak and continually renewed dental batteries
• Robust four-legged body supporting a massive head and neck

Lawrence Lambe recognised Centrosaurus apertus in 1904 while revisiting horned-dinosaur material collected from the Red Deer River district of Alberta. A frill originally assigned to Monoclonius carried distinctive hooked processes and large openings, prompting Lambe to establish a new genus and species. Later Canadian expeditions uncovered complete skulls, skeletons and extraordinary bonebeds throughout the Dinosaur Park Formation. The type material is housed in Canada's national collection, while the Royal Tyrrell, Royal Ontario and other museums preserve extensive growth series and bonebed samples.

Discovery credit: Geological Survey of Canada Red Deer River expeditions.

Naming authors: Lawrence M. Lambe.

The Dinosaur Park Formation preserves river channels, vegetated floodplains, ponds and coastal wetlands beside the Western Interior Seaway. Centrosaurus browsed among flowering plants, conifers and ferns alongside hadrosaurs, armoured dinosaurs and other ceratopsids. Gorgosaurus and Daspletosaurus were the largest predators. The formation records environmental change over roughly 1.5 million years, so all named animals were not necessarily neighbours at one moment.

Monodominant bonebeds containing hundreds or thousands of animals show that Centrosaurus sometimes gathered in very large numbers. Sedimentology indicates that floods and drowning contributed to several mass-death assemblages, after which carcasses were disarticulated and transported. The horns and frill likely functioned in display, recognition and physical interaction, but specific combat styles are not preserved. Bonebeds establish aggregation during particular events, not permanent herd size, migration routes or family structure.

• Some Centrosaurus bonebeds contain remains from hundreds or thousands of individuals.
• Its name refers to points or spurs, not to being the central dinosaur.
• The species name apertus refers to the large openings in the frill.
• A sample of 47 skulls helped researchers reconstruct how its horns and frill changed with age.

A research repository is not necessarily a public exhibit. Loan and display status can change, so check with the institution before visiting.

1. 01
   Palaeobiology Collections

   Canadian Museum of Nature

   Open source
2. 02
   On the squamoso-parietal crest of two species of horned dinosaurs from the Cretaceous of Alberta

   Lawrence M. Lambe · The Ottawa Naturalist 18(4) · 1904

   Open source
3. 03
   The taphonomy of a Centrosaurus bone bed from the Dinosaur Park Formation, Alberta, with comments on cranial ontogeny

   Michael J. Ryan, Anthony P. Russell, David A. Eberth, Philip J. Currie · PALAIOS 16(5) · 2001

   Open source
4. 04
   Craniofacial ontogeny in Centrosaurus apertus

   Joseph A. Frederickson, Allison R. Tumarkin-Deratzian · PeerJ 2, e252 · 2014

   Open source
5. 05
   Fossil Planet — Centrosaurus

   Royal Tyrrell Museum of Palaeontology

   Open source
6. 06
   A centrosaurine mega-bonebed from the Upper Cretaceous of southern Alberta: implications for behavior and death events

   David A. Eberth, Donald B. Brinkman, Vaia Barkas · New Perspectives on Horned Dinosaurs · 2010