# Gorgosaurus libratus

> An 8 to 9 m tyrannosaur from the Late Cretaceous of Alberta and Montana, the best-represented tyrannosaurid in the fossil record. A juvenile found with two young feathered dinosaurs in its stomach shows how its diet changed as it grew.

- Classification: Dinosauria (clade) > Saurischia (clade) > Theropoda (clade) > Coelurosauria (clade) > Tyrannosauroidea (superfamily) > Tyrannosauridae (family) > Albertosaurinae (subfamily) > Gorgosaurus (genus) > Gorgosaurus libratus (species)
- Length: 8–9 m
- Hip height: 2.3–2.8 m
- Mass: 2–3 t
- Age: 76.5–73 million years ago (Late Cretaceous)
- Fossils found in: Dinosaur Park Formation (Alberta); Canada
- Diet: carnivore
- Described: Lawrence M. Lambe, 1914

Canonical page: https://dinodex.club/dinosaurs/gorgosaurus-libratus
Last updated: 2026-09-27

## Overview

Gorgosaurus libratus lived about 75 million years ago on the coastal floodplains of the Dinosaur Park Formation in Alberta, Canada, and in Montana. Charles M. Sternberg found a nearly complete skeleton on the Red Deer River in 1913, and Lawrence Lambe named it in 1914; it was the first tyrannosaurid found with a complete hand.

It was a close relative of Albertosaurus, lighter built than Tyrannosaurus, with long legs and tiny two-fingered arms. Dozens of skeletons of all ages make it the best-known tyrannosaurid, and some researchers treat it as a species of Albertosaurus.

A juvenile, 5 to 7 years old and about 335 kg, preserves the hind legs of two yearling Citipes, small oviraptorosaurs, in its stomach (Therrien et al. 2023). Young Gorgosaurus hunted small, young dinosaurs and only later switched to large herbivores such as hadrosaurs and ceratopsians.

## Name meaning

"Fierce lizard", from Greek gorgos ("terrible, fierce") and sauros; libratus, Latin for "balanced" (Lambe 1914).

## Sources

1. (2026). Paleobiology Database: Gorgosaurus libratus type collection 11897. The Paleobiology Database (paleobiodb.org), data service 1.2, accessed 2026-09-23. https://paleobiodb.org/data1.2/colls/list.json?coll_id=11897&show=paleoloc,strat,loc,ref,geo&pgm=gplates&vocab=pbdb
2. (2026). Wikipedia: Gorgosaurus. Wikipedia (English), accessed 2026-09-24. https://en.wikipedia.org/wiki/Gorgosaurus
3. Currie, P. J. (2003). Allometric growth in tyrannosaurids (Dinosauria: Theropoda) from the Upper Cretaceous of North America and Asia. Canadian Journal of Earth Sciences 40: 651-665. https://doi.org/10.1139/e02-083
4. Lambe, L. M. (1914). On the fore-limb of a carnivorous dinosaur from the Belly River Formation of Alberta, and a new genus of Ceratopsia from the same horizon, with remarks on the integument of some Cretaceous herbivorous dinosaurs. The Ottawa Naturalist 27(10): 129-135.
5. Paul, G. S. (2016). The Princeton Field Guide to Dinosaurs (2nd edition). Princeton University Press.
6. Therrien, F., Zelenitsky, D. K., Tanaka, K., Voris, J. T., Erickson, G. M., Currie, P. J., DeBuhr, C. L. & Kobayashi, Y. (2023). Exceptionally preserved stomach contents of a young tyrannosaurid reveal an ontogenetic dietary shift in an iconic extinct predator. Science Advances 9: eadi0505. https://doi.org/10.1126/sciadv.adi0505

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Cite as: "Gorgosaurus libratus". DinoDex. https://dinodex.club/dinosaurs/gorgosaurus-libratus (updated 2026-09-27).