Temporal range: Late Cretaceous
Nanuq my beloved
Nanuqsaurus as it appeared in the documentary Prehistoric Planet
Scientific classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Sauropsida
Clade: Dinosauria
Order: Saurischia
Suborder: Theropoda
Family: Tyrannosauridae
Subfamily: Tyrannosaurinae
Genus: Nanuqsaurus
Fiorillo & Tykoski, 2014
Species: N. holgundi
Type species
Nanuqsaurus hoglundi
Fiorillo & Tykoski, 2014
  • Nanuqsaurus holgundi Fiorillo & Tykoski, 2014

Nanuqsaurus (Greek for "Polar bear lizard")[1] is an extinct genus of tyrannosaurid theropod dinosaur from Maastrichtian Alaska. It is only known from two specimens, DMNH 21461, a partial Skull roof found in Alaska and DMNH 6666 a partial snout also found in the Prince Creek Formation in 1995 but was previously referred to as Tyrannosaurus. This dinosaur may have only grew to about 6 m (19.7 ft) long, which was half the size of an average Tyrannosaurus. Its type and only species is referred to as N. hoglundi.

Naming and Discovery[]

The-tyrannosaur-nanuqsaurus-with-its-young-credit-james-havens web1

A nanuqsaurus with its young.(Art by James Havens)

In 2006, at the Kikak-Tegoseak Quarry, in North Slope Borough in the north of Alaska, fossils were found of a medium-sized theropod, with an estimated skull length of 600–700 mm (24–28 in). These were first referred to Gorgosaurus and later to Albertosaurus. After preparation in the Perot Museum of Nature and Science (Dallas Museum of Natural History) it was recognised these represented a species new to science. The holotype, DMNH 21461, has been found in a layer of the Prince Creek Formation, dated at 69.1 million years. It consists of a partial skull with a lower jaw, which were found very close together. It contains the nasal branch of the right maxilla; a partial skull roof including partial parietals, frontals and a right laterosphenoid; and the front of the left dentary. The specimen is from a fully mature individual, as it has a smooth nasal contact.

Nanuqsaurus was first described and named by Anthony R. Fiorillo and Ronald S. Tykoski in 2014. The type species is Nanuqsaurus hoglundi. The generic name is derived from the Iñupiaq word for "polar bear", nanuq, and the Greek word sauros, meaning "lizard". The specific name honors the philanthropist Forrest Hoglund, for his work on philanthropy and cultural institutions.


The holotype of Nanuqsaurus has been estimated to have been about six meters (twenty feet) long, about half the length of Tyrannosaurus. Since the discovery of the holotype, various undescribed material assigned to Nanuqsaurus reached larger sizes. It has been proposed that the holotype was from a juvenile Nanuqsaurus was a juvenile and adult specimens would have reached 9 meters in length, similar to other tyrannosaurids (Druckenmiller et. al.; 2021).

Nanuqsaurus bears a particularly shaped ridge on its head indicating the carnivore was closer related to Tyrannosaurus rex than those in Albertosaurinae. The length of the reconstructed skull, based on the proportions of related animals, is 60–70 cm (24–28 in).

Classified as a tyrannosaurine, Nanuqsaurus is diagnosed by: a thin, rostrally forked, median spur of the fused parietals on the dorsal skull roof that overlaps and separates the frontals within the sagittal crest, frontals with a long, rostrally pointed process separating the prefrontal and lacrimal facets and that the first two dentary teeth are much smaller than the dentary teeth behind them.


The holotype material of Nanuqsaurus.


The skull would have been around 50 cm (1.65 feet) when complete.


Nanuqsaurus lived in Alaska, preying on local fauna such as Edmontosaurus and Pachyrhinosaurus, just like its larger relative, Gorgosaurus. Nanuqsaurus likely competed for food with other predatory theropods such as Dromaeosaurus, Saurornitholestes, Troodon, and an unnamed genus of Saurornitholestine.

In the Media[]

  • Nanuqsaurus makes its first appearance in the subsequent Dino Dan series, Dino Dana.
  • It also makes its appearance in the NHK documentary Dinosaur Superworld, otherwise known as Amazing Dinoworld.
  • Nanuqsaurus appears in the PBS NOVA episode Arctic dinosaurs as refereed as Gorgosaurus or Albertosaurus.
  • Nanuqsaurus appears in the 2022 PBS NOVA episode "Alaskan Dinosaurs".
  • It also appears in T. rex: An Evolutionary Journey, which the narrator refers to it as a cousin of Tyrannosaurus rex.
  • A pack of 3 Nanuqsaurus appears in the 4th episode of the 2022 BBC Documentary Prehistoric Planet, in episode 4 titled “Ice Worlds.” Nanuqsaurus is shown ganging up to hunt a herd of Pachyrhinosaurus similar to modern wolves hunting musk oxen. Nanuqsaurus returns in the 2nd Season of Prehistoric Planet on the 5th episode titled “North America.” Where a female Nanuqsaurus was hunting a group of Ornithomimus. She catches one & brings it back home for not only for herself, but also for her babies to feed on.
  • Nanuqsaurus is confirmed to appear in the upcoming Documentary; Surviving Earth.


Nanuqsaurus (2)

Artist's depiction of a Nanuqsaurus head; partially covered in feathers


  1. Prehistoric News: The Pygmy Tyrannosaur by Theprehistoricmaster.