Anzu lived in the humid, subtropical coastal floodplains of the Hell Creek Formation across present-day North and South Dakota, United States, during the latest Cretaceous Period (Maastrichtian stage, ~68 to 66 million years ago), sharing its ecosystem with Tyrannosaurus rex, Triceratops, and Ankylosaurus.

What kind of dinosaur was Anzu?

Anzu is classified as a caenagnathid oviraptorosaur, a clade of highly bird-like theropods with hollow bones, fused wishbones, and pneumatic skeletal elements. Before the discovery of Anzu, North American caenagnathids were known mostly from fragmentary jaw or limb fragments.

Anzu (Anzu wyliei) - Size, Hell Creek Fossils & 'Chicken from Hell'

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Anzu (Anzu wyliei) - Size, Hell Creek Fossils & 'Chicken from Hell' | DinoOrigin

Evolutionary Taxonomy & Cladistics

View Dinosaur Phylogeny

Phylogenetic classification of Anzu wyliei Lamanna et al., 2014 based on peer-reviewed cladistic analyses of diagnostic skeletal synapomorphies.

Taxonomic Rank	Taxon / Clade	Diagnostic Context
Kingdom	Animalia	Monophyletic prehistoric clade
Phylum	Chordata	Monophyletic prehistoric clade
Clade	Dinosauria	Monophyletic prehistoric clade
Order	Saurischia (Lizard-Hipped Dinosaurs)	Characterized ancestrally by a triradiate pelvis with an anteriorly pointing pubis.
Suborder	Theropoda	Bipedal saurischian dinosaurs, historically dominated by carnivores and including the avian lineage.
Genus	Anzu	Monophyletic prehistoric clade
Species	Anzu wyliei Lamanna et al., 2014	Specific authority designation

At a Glance & Hell Creek Ecology

How Big Was Anzu?

"The Chicken from Hell"

Total Length3.0–3.5 m10–11.5 ft

Estimated Mass200–300 kg440–660 lbs

Standing Height1.5–1.8 m5–6 ft at crest

Geological Epoch68–66 MaLate Maastrichtian

What was Anzu? Anzu wyliei was a gigantic, crested caenagnathid oviraptorosaur that lived in the humid river floodplains of the Hell Creek Formation (North and South Dakota) during the final two million years of the dinosaurian era. Colloquially nicknamed "the Chicken from Hell" by paleontologists Matthew Lamanna and colleagues in 2014, Anzu was one of the largest oviraptorosaurs in North America, measuring over 3 meters in length and standing shoulder-to-shoulder with an adult human.

Diet & Ecological Role: Anzu was an omnivore equipped with a toothless, keratinous beak featuring specialized shearing ridges on the palate. Its flexible feeding apparatus allowed it to consume plants, cycad seeds, small mammals, amphibians, and eggs, coexisting alongside apex predators like Tyrannosaurus rex and heavy armored herbivores like Ankylosaurus.

Anatomy & Physical Characteristics

Anzu was a bizarre, bird-like oviraptorosaur that lived alongside Tyrannosaurus rex in the Late Cretaceous Hell Creek Formation. Nicknamed the 'Chicken from Hell', it measured over 3.5 meters long and weighed approximately 250 kilograms, making it one of the largest North American caenagnathids known.

Its skull bore a tall, paper-thin bony crest, while its jaws were toothless and covered in a keratinous beak with specialized shearing edges.

Diagnostic Morphological Traits

Large, tall-crested biped with long slender legs, feathered wings, toothless beak, and a short fan-tailed plumage.

Comparative Scale & Biometrics

Anatomical dimensions relative to an average adult human (1.8 m / 6 ft tall)

Approx. 1.9× human length

Anzu (Length)3–3.5 m (9.8–11.5 ft)

Adult Human1.8 m (6.0 ft)

Length

3–3.5 m (9.8–11.5 ft)

Height

1.5–1.8 m (4.9–5.9 ft)

Estimated Mass

200–300 kg (441–661 lbs)

Diet & Feeding Ecology

All Omnivore Species

Trophic Guild: Omnivore

Omnivorous; consumed plants, seeds, small mammals, amphibians, and eggs.

Paleobiology & Behavior

Omnivorous forager utilizing its long legs to travel across floodplains while feeding on varied vegetation and small prey. Living in the Hell Creek ecosystem alongside colossal herbivores like Triceratops and apex predators like Tyrannosaurus rex, Anzu occupied a distinct mid-sized omnivorous ecological guild.

Habitat & Ecological Biome

Prehistoric Depositional Setting

Humid lowland coastal floodplains, swamp forests, and subtropical river channels.

Fossil Evidence & Specimen Records

Preserved Skeletal Material & Bonebeds

Three partial skeletons providing an almost complete picture of the skeletal anatomy.

Discovery & Taxonomic Naming History

Year of Discovery / Description1998

Type Specimen Locality & FormationHell Creek Formation, North and South Dakota, United States

Described by Matthew Lamanna, Hans-Dieter Sues, Emma Schachner, and Tyler Lyson in 2014.

Geological Era & Chronostratigraphy

Explore All Cretaceous Period Fauna

Cretaceous Period PeriodTemporal Interval: 68–66 Ma (million years ago)

The longest and final period of the Mesozoic Era, characterized by the rise of flowering plants, ceratopsians, hadrosaurs, tyrannosaurids, and concluding with the Chicxulub asteroid impact.

Where It Lived & Paleoenvironment

North America Dinosaurs

During the Mesozoic Era, continental drift progressively reconfigured land bridges, atmospheric currents, and regional precipitation regimes. Fossils of Anzu evidence its adaptation to the paleoenvironments of North America.

Paleogeographic RealmNorth America (North America)

Home to the fossil-rich Morrison Formation of the Late Jurassic and the Hell Creek and Dinosaur Park Formations of the Late Cretaceous.

Fossil Discovery Locality

Scientific Significance & Evolutionary Impact

The anatomical architecture of Anzu serves as a crucial benchmark in vertebrate paleontology, illustrating key adaptive radiations within Theropoda.

Phylogenetic Placement: Informs cladistic debates concerning the divergence, skull biomechanics, and skeletal evolution of Cretaceous Period fauna.
Paleoecological Guild: Documents trophic specialization (Omnivore) and predator-prey dynamics across its regional ecosystem.
Taphonomic Record: Three partial skeletons providing an almost complete picture of the skeletal anatomy.

Frequently Asked Questions About Anzu

Scientifically verified answers based on peer-reviewed paleontological evidence.

Q1.How big was Anzu?

Anzu wyliei was one of the largest known caenagnathid oviraptorosaurs in North America, measuring approximately 3.0 to 3.5 meters (10 to 11.5 feet) in total length, standing 1.5 to 1.8 meters (5 to 6 feet) tall at the head/hips, and weighing an estimated 200 to 300 kg (440 to 660 lbs).

Q2.Why was Anzu nicknamed the 'Chicken from Hell'?

When described by paleontologists Matthew Lamanna, Hans-Dieter Sues, Emma Schachner, and Tyler Lyson in 2014, Anzu was colloquially nicknamed the 'Chicken from Hell' (reflecting its genus name after Anzû, a feathered demon in Mesopotamian mythology, and its recovery from the Hell Creek Formation). With its toothless beak, tall cranial crest, feathered wings, and large bird-like body, it presented a formidable appearance.

Q3.What did Anzu eat?

Anzu was an omnivore. Its jaws lacked teeth but featured a sharp, keratinous rhamphotheca (beak) with specialized shearing ridges on the palate, adapted for processing fibrous vegetation, seeds, fruits, small mammals, amphibians, and eggs.

Q4.Where did Anzu live?

Academic Literature & Peer-Reviewed References

Authoritative citations establishing the factual taxonomy, biometrics, and anatomy of Anzu.

PLoS ONEView Publication
Lamanna, M. C., Sues, H.-D., Schachner, E. R., & Lyson, T. R. (2014). A new large-bodied oviraptorosaurian theropod dinosaur from the latest Cretaceous of western North America. PLoS ONE, 9(3), e92022. https://doi.org/10.1371/journal.pone.0092022
Curated & Verified: 2026-09-24

Anzu

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