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Tyrannosauridae

Gorgosaurus libratus GOR-go-SOR-us

"Fierce lizard"

Gorgosaurus silhouette
You 1.8 m (5.9 ft) tall
Gorgosaurus 9 m (29.5 ft) long
as long as 6 people standing fingertip to fingertip
silhouette · Ivan Iofrida (CC-BY) via PhyloPic
Length
9 m (29.5 ft) — About 9 m long, ~2.5 tonnes — very similar to Albertosaurus.
Period
Late Cretaceous (77–75 Mya)
Place
North America · Alberta, Canada · Montana
Food
Carnivore — Hadrosaurs, ceratopsians, and ankylosaurs — a generalist predator.
Clade
Tyrannosauridae Dinosauria Saurischia Theropoda Coelurosauria Tyrannosauroidea Late-Cretaceous tyrants: T. rex, Tarbosaurus, Albertosaurus.

The "fierce lizard" of ancient Alberta, and the best-known tyrannosaur of all.

Gorgosaurus is one of the best-known tyrannosaurs because so many complete skeletons have been found. It lived a few million years before Albertosaurus in nearly the same place, and the two look so similar that scientists sometimes lump them together. A 2009 skeleton of a juvenile included gut contents — the last meal of its life, made up of the legs of two young birdlike theropods.

More about Gorgosaurus

Discovery

Named by Lawrence Lambe · 1914 · The holotype was found in the Dinosaur Park Formation of Alberta, Canada.

Lawrence Lambe first described and named Gorgosaurus libratus in 1914. The holotype, a nearly complete skeleton with a skull, had been discovered in 1913 by Charles M. Sternberg and was the first tyrannosaurid found with a complete hand.

The name comes from Greek: gorgos meaning "fierce" or "terrible", and saurus meaning "lizard". The species name libratus is from the Latin verb librare, "to balance", and means "balanced".

Lawrence Lambe. Lambe was the paleontologist who first described and named Gorgosaurus libratus in 1914.

Is Gorgosaurus even its own genus?
Gorgosaurus libratus and Albertosaurus sarcophagus are extremely similar, differing mainly in subtle teeth and skull features. Because Albertosaurus was named first, some experts treat Gorgosaurus as a junior synonym, and Dale Russell formally reassigned it as Albertosaurus libratus in 1970. The distinction remains debated, with other experts keeping the two genera separate.
How did two big predators share one floodplain?
In some areas Gorgosaurus lived alongside another tyrannosaurA large-headed, small-armed predatory theropod lineage (T. rex and kin)., Daspletosaurus, and the two were roughly the same size. There is some evidence of niche differentiation between them, which may have let both apex predators coexist in the same lush, inland-sea environment.

What we know

  • More than 20 skeletons known, ranging from juveniles to large adults.
  • Same general body plan as Albertosaurus: long legs, large head, two-fingered hands.
  • A juvenile preserved with its last meal in its gut — bones of two young oviraptorosaurs.
  • Lived in the Dinosaur Park Formation alongside Centrosaurus, Corythosaurus, Daspletosaurus.

What we guess

  • Whether Gorgosaurus and Albertosaurus are different enough to be separate genera.
  • How it shared territory with Daspletosaurus — another tyrannosaur in the same formation.
  • Whether the species changed hunting style as they grew, like some living predators do.