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Albertosaurus, Late CretaceousHorseshoe Canyon Formation, Alberta · named 1905
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Albertosaurus

al-BER-tuh-SORE-us

"Alberta lizard"

Lived
84 to 66 million years ago, Late Cretaceous
Diet
Carnivore
Length
about 9 m (30 ft)
Group
Theropods, Tyrannosauridae
Found in
Canada
Named by
Osborn 1905

Size comparison

To scale

Where its fossils were found

The evidence

Today

21 finds

75 million years ago

Map: C. R. Scotese, PALEOMAP

Also reported from United States.

Habitat

River channels and low floodplains in the Horseshoe Canyon Formation of Alberta. Edmontosaurus, Ornithomimus and Struthiomimus were among the dinosaurs of this region.

Field notes

About Albertosaurus

What it was like

Albertosaurus was a bipedal predator with a massive head, rows of sharp teeth, and small, two-fingered arms. It grew to about 9 meters (30 feet) long, smaller than its famous relative Tyrannosaurus but still a formidable hunter.

It probably had a strong sense of smell and good eyesight, useful for finding prey across open floodplains. Some paleontologists think Albertosaurus may have hunted or scavenged in groups, based on a bonebed where the remains of several individuals were found together.

Its world

Albertosaurus lived from about 84 to 66 million years ago, in the Late Cretaceous, mostly in what is now Alberta, Canada, with possible remains also reported from Saskatchewan and the states of Montana and Missouri in the United States. Its fossils come from formations including Horseshoe Canyon, Judith River, Oldman, and Scollard.

It shared its world with the armored Euoplocephalus, the ostrich-like Ornithomimus and Struthiomimus, the small hunter Troodon, and close relatives such as Gorgosaurus and Daspletosaurus.

How it was found

Osborn named Albertosaurus in 1905. Since then, paleontologists have recovered about 21 fossil finds, giving Albertosaurus one of the more complete fossil records among tyrannosaurids. Some scientists count the closely related Gorgosaurus as a second species of Albertosaurus, while others treat it as a separate genus; the question is still debated.

Field gallery

More views of Albertosaurus

Scenes reconstructed from the available fossil evidence.

Albertosaurus in its habitat, photo 1

1 of 7

Lived alongside

Found in the same rock formations

A rock formation can hold fossils laid down millions of years apart, so not every animal here met Albertosaurus.

The evidence

The science behind Albertosaurus

Which parts of the picture come from its own bones, and which come from its relatives.

From its own fossils

  • Skulls and skeletons show a relatively slender tyrannosaur with long lower legs and small brow ridges.
  • A bonebed contains Albertosaurus of different ages, from juveniles to adults.
  • Preserved skin impressions show small scales.

Borrowed from relatives

  • Much of its skeleton is known directly, with Gorgosaurus providing a close comparison for missing parts.
  • Lips covering the teeth are inferred from comparisons with other theropods, including Tyrannosaurus.

Still unknown

  • Whether groups hunted together or simply gathered in the same places.
  • Its color and the skin covering of juveniles.
  • Whether adults cared for their young.

Often drawn wrong

  • Giving it the stocky proportions of Tyrannosaurus loses its lighter build and longer lower legs.
  • Its hands had two main fingers, with palms facing inward.
  • Large horns above the eyes replace the small brow ridges shown by its skull.

Discovery timeline

  1. 1905Named itOsborn
  2. 2004Growing upErickson et al.
  3. 2006Growing upErickson et al.
  4. 2017SkinBell et al.
  5. 2023Close relativeCullen et al.

Key papers

The research behind what we know of Albertosaurus

Close relatives

Other members of Tyrannosauridae

Sources: Wikidata