Dinosaur genus

Trierarchuncus

Fowler et al. 2020

Trierarchuncus is a dinosaur genus known from bones, found in rocks 72.2–66 million years old, in the United States.

Confidence labels

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Confidence labels are switched off. Facts with low confidence, or where sources disagree, still carry a small dot: tap it for the reason.

At a glance

Data as of 11 October 2026

72.2–66 Ma

Triassic

Jurassic

Cretaceous

252 million years ago20114366

The last non-bird dinosaurs died out 66 million years ago. That's as far from us as the end of this bar.

Named by: Fowler et al. 2020
medium
medium: Only PBDB gives this; nothing contradicts it.
Sources
Given by: Paleobiology Database. How it was chosen: PBDB leads.
Described in: D. W. Fowler, J. P. Wilson, E. A. Freedman Fowler, C. R. Noto, D. Anduza, J. R. Horner (2020). Trierarchuncus prairiensis gen. et sp. nov., the last alvarezsaurid: Hell Creek Formation (uppermost Maastrichtian), Montana. Cretaceous Research 116: 104560. Read it
medium
medium: Only PBDB gives this; its author and year match the naming authority (Fowler et al. 2020).
Sources
Given by: Paleobiology Database. The publication the Paleobiology Database gives as the authority for this genus name, usually the one that first named and described it.
Lived: Maastrichtian, 72.2–66 million years ago
medium
medium: Only PBDB gives this; nothing contradicts it.
Omnisaura calculation72.2–66 million years ago, from its dated fossil records
medium
medium: Omnisaura's calculation from 6 confirmed PBDB records.
Sources
Given by: Paleobiology Database. How it was chosen: PBDB leads.
Fossils found in: United States
medium
medium: Only PBDB records it (6 records).
Sources
Given by: Paleobiology Database. How it was chosen: Union of all sources (ISO 3166).
Rock formations: Hell Creek Formation
medium
medium: Only PBDB records it (6 records).
Sources
Given by: Paleobiology Database. How it was chosen: Canonical names, automatic and editor-approved matches applied.
Family: Alvarezsauridae
medium
medium: Only PBDB gives this; nothing contradicts it.
Sources
Given by: Paleobiology Database. How it was chosen: PBDB leads.
Parent group: Alvarezsauridae
medium
medium: Only PBDB gives this; nothing contradicts it.
Sources
Given by: Paleobiology Database. How it was chosen: PBDB leads.
Species named in its records: Trierarchuncus prairiensis
Sources
Given by: Paleobiology Database (the species its fossil records are identified as).
Diet: carnivore (inferred for its group)
medium
medium: Only PBDB gives this, and it infers it for the whole of Coelurosauria, the group this genus belongs to, not from this genus's own fossils.
Sources
Given by: Paleobiology Database. How it was chosen: PBDB, inferred from a group the genus belongs to.
Way of life: ground dwelling, solitary (inferred for its group)
low
low: PBDB infers this way of life for the whole of Theropoda; behaviour is rarely known for one genus.
Sources
Given by: Paleobiology Database. How it was chosen: PBDB, inferred from a group the genus belongs to.
Known from: Bones
Sources
Given by: Paleobiology Database (what the name was based on).

Sources: Paleobiology Database (CC BY 4.0), Natural History Museum Data Portal (CC0 1.0)Confidence levels and gaps are Omnisaura's own assessment.

Gaps are answers

What isn't known yet

Type species: no source we use gives it yet.
Order: no source we use gives it yet.
Common names: no source we use gives it yet.
What it was named after: no source we use gives it yet.
Resting on one source: 6 facts come from a single source with nothing against them (rated medium): name (PBDB); authority (PBDB); parent group (PBDB); family (PBDB); age (headline) (PBDB); diet (PBDB).

Size and appearance aren't covered yet, and diet and way of life only as PBDB infers them for the wider group. Omnisaura leaves the rest out rather than guess.

Where sources disagree

None open. Where our sources overlap, they agree on everything shown here.

Did it meet…?

Did Trierarchuncus meet ?

Yes. Both are found, identified to species, in the same rocks of the same age: Hell Creek.

Going by the ages and rock formations of their dated fossils, as on the map. Compare their fossil sites on the map.

Connections

Genera linked to Trierarchuncus by where and when their fossils were found, by classification and by who named them. Select a name to open its page.

Same rocks, same time 27

Genera found in the same rock units, from rocks of overlapping age, the most shared fossil sites first.

Triceratops Tyrannosaurus Edmontosaurus Thescelosaurus Richardoestesia Paronychodon Pachycephalosaurus Chirostenotes Saurornitholestes Troodon Ankylosaurus Anzu Leptoceratops Nanotyrannus Torosaurus Acheroraptorand 11 more

Same family: Alvarezsauridae 10

Other genera in Alvarezsauridae with a full profile.

Achillesaurus Albertonykus Albinykus Alnashetri Alvarezsaurus Ceratonykus Elopteryx Linhenykus Mononykus Shuvuuia

Found in United States 54

Other genera found in United States, from rocks of overlapping age, the most fossil sites there first.

Triceratops Tyrannosaurus Edmontosaurus Thescelosaurus Paronychodon Richardoestesia Pachycephalosaurus Alamosaurus Troodon Saurornitholestes Dromaeosaurus Ankylosaurus Chirostenotes Ornithomimus Glyptodontopelta Edmontoniaand 38 more

Credits

Where this page comes from

Paleobiology DatabaseCC BY 4.0 · fossil records, ages, classification
Natural History Museum Data PortalCC0 1.0 · catalogued specimens
OmnisauraOmnisaura editorial · confidence levels and gaps
PaleoMAP PaleoCoastlines (Kocsis and Scotese 2021)CC BY 4.0 · ancient coastlines on the small map
Natural EarthPublic domain · today's coastlines