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Science & Nature • Paleontology

Albertosaurus

Albertosaurus is a genus of tyrannosaurid theropod dinosaurs from the Late Cretaceous of western North America.

By Ethan Anderson| Reviewed by Olivia Bennett, Standards & Fact-Checking Lead| Updated July 26, 2026|2 min read| Fact-checked

Albertosaurus is a genus of tyrannosaurid theropod dinosaurs from the Late Cretaceous of western North America. The best-known species, Albertosaurus sarcophagus, was a large, bipedal carnivore named for Alberta, Canada, where many fossils have been found. It is a close relative of Tyrannosaurus but lived earlier and was generally smaller and more lightly built.

Discovery and naming

Albertosaurus was named in 1905 by Henry Fairfield Osborn. Its name refers to Alberta, the Canadian province where many fossils were discovered.

Classification

Albertosaurus belongs to Tyrannosauridae, within the theropod dinosaurs. Some sources describe it as an early subgroup of tyrannosaurs or closely related to Tyrannosaurus.

Anatomy and size

Albertosaurus had a large skull, serrated teeth, short forelimbs, and strong hind limbs for bipedal movement. Adult length estimates are commonly around 9 to 10 metres.

Fossil distribution

Fossils are known mainly from Alberta, but also from parts of Alaska and the western United States in some sources. The genus is especially associated with the Horseshoe Canyon Formation in Alberta.

Key facts

  • Albertosaurus is a genus of large tyrannosaurid dinosaurs.
  • Most fossils have been found in Canada, especially Alberta.
  • It lived during the Late Cretaceous, roughly 76–68 million years ago, depending on the source.
  • It was a two-legged carnivore with a large head, strong hind limbs, and short forelimbs with two fingers.
  • Albertosaurus was smaller and more lightly built than Tyrannosaurus rex.
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Canadian context

Albertosaurus is strongly associated with Canada because many of its fossils were found in Alberta, and its name honours the province.[1][4][6][11]

Frequently asked questions

What is Albertosaurus?
Albertosaurus is a genus of tyrannosaurid theropod dinosaurs that lived in the Late Cretaceous of North America.
Where have Albertosaurus fossils been found?
Most fossils come from Canada, especially Alberta, with additional finds reported from other parts of western North America.
Was Albertosaurus a predator?
Yes. It was a carnivorous dinosaur with adaptations for hunting and eating meat.
How big was Albertosaurus?
Adult Albertosaurus are commonly estimated at about 9 to 10 metres long, though estimates vary by source.
How is Albertosaurus related to Tyrannosaurus rex?
Albertosaurus was a close relative of Tyrannosaurus rex but lived earlier and was generally smaller and more lightly built.
What does the name Albertosaurus mean?
The name means 'Alberta lizard' and refers to Alberta, Canada.

References

  1. San Diego Natural History Museum — https://www.sdnhm.org/exhibitions/fossil-mysteries/fossil-field-guide-a-z/albertosaurus/
    Supports: Late Cretaceous age, North American range, Alberta fossils, size, body plan
  2. Natural History Museum (UK) — https://www.nhm.ac.uk/discover/dino-directory/albertosaurus.html
    Supports: Name meaning, classification, length, diet, movement, time period, fossil locality
  3. Encyclopaedia Britannica — https://www.britannica.com/animal/Albertosaurus
    Supports: Genus status, Late Cretaceous occurrence, tyrannosaur relationship
  4. Australian Museum — https://www.australian.museum/learn/dinosaurs/fact-sheets/albertosaurus-sarcophagus/
    Supports: Name meaning, Alberta connection, predator status, general description
  5. GBIF — https://www.gbif.org/species/113437661
    Supports: Taxonomic name, Late Cretaceous occurrence, Alberta naming connection
  6. Wikipedia — https://www.wikipedia.org/wiki/Albertosaurus
    Supports: General overview, geologic age, taxonomy, naming